Linux From Scratch .info files

This is gettext.info, produced by makeinfo version 4.8 from
gettext.texi.

INFO-DIR-SECTION GNU Gettext Utilities
START-INFO-DIR-ENTRY
* gettext: (gettext). GNU gettext utilities.
* autopoint: (gettext)autopoint Invocation. Copy gettext infrastructure.
* envsubst: (gettext)envsubst Invocation. Expand environment variables.
* gettextize: (gettext)gettextize Invocation. Prepare a package for gettext.
* msgattrib: (gettext)msgattrib Invocation. Select part of a PO file.
* msgcat: (gettext)msgcat Invocation. Combine several PO files.
* msgcmp: (gettext)msgcmp Invocation. Compare a PO file and template.
* msgcomm: (gettext)msgcomm Invocation. Match two PO files.
* msgconv: (gettext)msgconv Invocation. Convert PO file to encoding.
* msgen: (gettext)msgen Invocation. Create an English PO file.
* msgexec: (gettext)msgexec Invocation. Process a PO file.
* msgfilter: (gettext)msgfilter Invocation. Pipe a PO file through a filter.
* msgfmt: (gettext)msgfmt Invocation. Make MO files out of PO files.
* msggrep: (gettext)msggrep Invocation. Select part of a PO file.
* msginit: (gettext)msginit Invocation. Create a fresh PO file.
* msgmerge: (gettext)msgmerge Invocation. Update a PO file from template.
* msgunfmt: (gettext)msgunfmt Invocation. Uncompile MO file into PO file.
* msguniq: (gettext)msguniq Invocation. Unify duplicates for PO file.
* ngettext: (gettext)ngettext Invocation. Translate a message with plural.
* xgettext: (gettext)xgettext Invocation. Extract strings into a PO file.
* ISO639: (gettext)Language Codes. ISO 639 language codes.
* ISO3166: (gettext)Country Codes. ISO 3166 country codes.
END-INFO-DIR-ENTRY

This file provides documentation for GNU `gettext' utilities. It
also serves as a reference for the free Translation Project.

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.

File: gettext.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)

GNU `gettext' utilities
***********************

This manual documents the GNU gettext tools and the GNU libintl library,
version 0.14.4.

* Menu:

* Introduction:: Introduction
* Basics:: PO Files and PO Mode Basics
* Sources:: Preparing Program Sources
* Template:: Making the PO Template File
* Creating:: Creating a New PO File
* Updating:: Updating Existing PO Files
* Manipulating:: Manipulating PO Files
* Binaries:: Producing Binary MO Files
* Users:: The User's View
* Programmers:: The Programmer's View
* Translators:: The Translator's View
* Maintainers:: The Maintainer's View
* Programming Languages:: Other Programming Languages
* Conclusion:: Concluding Remarks

* Language Codes:: ISO 639 language codes
* Country Codes:: ISO 3166 country codes

* Program Index:: Index of Programs
* Option Index:: Index of Command-Line Options
* Variable Index:: Index of Environment Variables
* PO Mode Index:: Index of Emacs PO Mode Commands
* Autoconf Macro Index:: Index of Autoconf Macros
* Index:: General Index

--- The Detailed Node Listing ---

Introduction

* Why:: The Purpose of GNU `gettext'
* Concepts:: I18n, L10n, and Such
* Aspects:: Aspects in Native Language Support
* Files:: Files Conveying Translations
* Overview:: Overview of GNU `gettext'

PO Files and PO Mode Basics

* Installation:: Completing GNU `gettext' Installation
* PO Files:: The Format of PO Files
* Main PO Commands:: Main Commands
* Entry Positioning:: Entry Positioning
* Normalizing:: Normalizing Strings in Entries

Preparing Program Sources

* Triggering:: Triggering `gettext' Operations
* Preparing Strings:: Preparing Translatable Strings
* Mark Keywords:: How Marks Appear in Sources
* Marking:: Marking Translatable Strings
* c-format Flag:: Telling something about the following string
* Special cases:: Special Cases of Translatable Strings
* Names:: Marking Proper Names for Translation
* Libraries:: Preparing Library Sources

Making the PO Template File

* xgettext Invocation:: Invoking the `xgettext' Program

Creating a New PO File

* msginit Invocation:: Invoking the `msginit' Program
* Header Entry:: Filling in the Header Entry

Updating Existing PO Files

* msgmerge Invocation:: Invoking the `msgmerge' Program
* Translated Entries:: Translated Entries
* Fuzzy Entries:: Fuzzy Entries
* Untranslated Entries:: Untranslated Entries
* Obsolete Entries:: Obsolete Entries
* Modifying Translations:: Modifying Translations
* Modifying Comments:: Modifying Comments
* Subedit:: Mode for Editing Translations
* C Sources Context:: C Sources Context
* Auxiliary:: Consulting Auxiliary PO Files
* Compendium:: Using Translation Compendia

Using Translation Compendia

* Creating Compendia:: Merging translations for later use
* Using Compendia:: Using older translations if they fit

Manipulating PO Files

* msgcat Invocation:: Invoking the `msgcat' Program
* msgconv Invocation:: Invoking the `msgconv' Program
* msggrep Invocation:: Invoking the `msggrep' Program
* msgfilter Invocation:: Invoking the `msgfilter' Program
* msguniq Invocation:: Invoking the `msguniq' Program
* msgcomm Invocation:: Invoking the `msgcomm' Program
* msgcmp Invocation:: Invoking the `msgcmp' Program
* msgattrib Invocation:: Invoking the `msgattrib' Program
* msgen Invocation:: Invoking the `msgen' Program
* msgexec Invocation:: Invoking the `msgexec' Program
* libgettextpo:: Writing your own programs that process PO files

Producing Binary MO Files

* msgfmt Invocation:: Invoking the `msgfmt' Program
* msgunfmt Invocation:: Invoking the `msgunfmt' Program
* MO Files:: The Format of GNU MO Files

The User's View

* Matrix:: The Current `ABOUT-NLS' Matrix
* Installers:: Magic for Installers
* End Users:: Magic for End Users

The Programmer's View

* catgets:: About `catgets'
* gettext:: About `gettext'
* Comparison:: Comparing the two interfaces
* Using libintl.a:: Using libintl.a in own programs
* gettext grok:: Being a `gettext' grok
* Temp Programmers:: Temporary Notes for the Programmers Chapter

About `catgets'

* Interface to catgets:: The interface
* Problems with catgets:: Problems with the `catgets' interface?!

About `gettext'

* Interface to gettext:: The interface
* Ambiguities:: Solving ambiguities
* Locating Catalogs:: Locating message catalog files
* Charset conversion:: How to request conversion to Unicode
* Plural forms:: Additional functions for handling plurals
* GUI program problems:: Another technique for solving ambiguities
* Optimized gettext:: Optimization of the *gettext functions

Temporary Notes for the Programmers Chapter

* Temp Implementations:: Temporary - Two Possible Implementations
* Temp catgets:: Temporary - About `catgets'
* Temp WSI:: Temporary - Why a single implementation
* Temp Notes:: Temporary - Notes

The Translator's View

* Trans Intro 0:: Introduction 0
* Trans Intro 1:: Introduction 1
* Discussions:: Discussions
* Organization:: Organization
* Information Flow:: Information Flow
* Prioritizing messages:: How to find which messages to translate first

Organization

* Central Coordination:: Central Coordination
* National Teams:: National Teams
* Mailing Lists:: Mailing Lists

National Teams

* Sub-Cultures:: Sub-Cultures
* Organizational Ideas:: Organizational Ideas

The Maintainer's View

* Flat and Non-Flat:: Flat or Non-Flat Directory Structures
* Prerequisites:: Prerequisite Works
* gettextize Invocation:: Invoking the `gettextize' Program
* Adjusting Files:: Files You Must Create or Alter
* autoconf macros:: Autoconf macros for use in `configure.in'
* CVS Issues:: Integrating with CVS
* Release Management:: Creating a Distribution Tarball

Files You Must Create or Alter

* po/POTFILES.in:: `POTFILES.in' in `po/'
* po/LINGUAS:: `LINGUAS' in `po/'
* po/Makevars:: `Makevars' in `po/'
* configure.in:: `configure.in' at top level
* config.guess:: `config.guess', `config.sub' at top level
* mkinstalldirs:: `mkinstalldirs' at top level
* aclocal:: `aclocal.m4' at top level
* acconfig:: `acconfig.h' at top level
* config.h.in:: `config.h.in' at top level
* Makefile:: `Makefile.in' at top level
* src/Makefile:: `Makefile.in' in `src/'
* lib/gettext.h:: `gettext.h' in `lib/'

Autoconf macros for use in `configure.in'

* AM_GNU_GETTEXT:: AM_GNU_GETTEXT in `gettext.m4'
* AM_GNU_GETTEXT_VERSION:: AM_GNU_GETTEXT_VERSION in `gettext.m4'
* AM_PO_SUBDIRS:: AM_PO_SUBDIRS in `po.m4'
* AM_ICONV:: AM_ICONV in `iconv.m4'

Integrating with CVS

* Distributed CVS:: Avoiding version mismatch in distributed development
* Files under CVS:: Files to put under CVS version control
* autopoint Invocation:: Invoking the `autopoint' Program

Other Programming Languages

* Language Implementors:: The Language Implementor's View
* Programmers for other Languages:: The Programmer's View
* Translators for other Languages:: The Translator's View
* Maintainers for other Languages:: The Maintainer's View
* List of Programming Languages:: Individual Programming Languages
* List of Data Formats:: Internationalizable Data

The Translator's View

* c-format:: C Format Strings
* objc-format:: Objective C Format Strings
* sh-format:: Shell Format Strings
* python-format:: Python Format Strings
* lisp-format:: Lisp Format Strings
* elisp-format:: Emacs Lisp Format Strings
* librep-format:: librep Format Strings
* scheme-format:: Scheme Format Strings
* smalltalk-format:: Smalltalk Format Strings
* java-format:: Java Format Strings
* csharp-format:: C# Format Strings
* awk-format:: awk Format Strings
* object-pascal-format:: Object Pascal Format Strings
* ycp-format:: YCP Format Strings
* tcl-format:: Tcl Format Strings
* perl-format:: Perl Format Strings
* php-format:: PHP Format Strings
* gcc-internal-format:: GCC internal Format Strings
* qt-format:: Qt Format Strings

Individual Programming Languages

* C:: C, C++, Objective C
* sh:: sh - Shell Script
* bash:: bash - Bourne-Again Shell Script
* Python:: Python
* Common Lisp:: GNU clisp - Common Lisp
* clisp C:: GNU clisp C sources
* Emacs Lisp:: Emacs Lisp
* librep:: librep
* Scheme:: GNU guile - Scheme
* Smalltalk:: GNU Smalltalk
* Java:: Java
* C#:: C#
* gawk:: GNU awk
* Pascal:: Pascal - Free Pascal Compiler
* wxWindows:: wxWindows library
* YCP:: YCP - YaST2 scripting language
* Tcl:: Tcl - Tk's scripting language
* Perl:: Perl
* PHP:: PHP Hypertext Preprocessor
* Pike:: Pike
* GCC-source:: GNU Compiler Collection sources

sh - Shell Script

* Preparing Shell Scripts:: Preparing Shell Scripts for Internationalization
* gettext.sh:: Contents of `gettext.sh'
* gettext Invocation:: Invoking the `gettext' program
* ngettext Invocation:: Invoking the `ngettext' program
* envsubst Invocation:: Invoking the `envsubst' program
* eval_gettext Invocation:: Invoking the `eval_gettext' function
* eval_ngettext Invocation:: Invoking the `eval_ngettext' function

Perl

* General Problems:: General Problems Parsing Perl Code
* Default Keywords:: Which Keywords Will xgettext Look For?
* Special Keywords:: How to Extract Hash Keys
* Quote-like Expressions:: What are Strings And Quote-like Expressions?
* Interpolation I:: Invalid String Interpolation
* Interpolation II:: Valid String Interpolation
* Parentheses:: When To Use Parentheses
* Long Lines:: How To Grok with Long Lines
* Perl Pitfalls:: Bugs, Pitfalls, and Things That Do Not Work

Internationalizable Data

* POT:: POT - Portable Object Template
* RST:: Resource String Table
* Glade:: Glade - GNOME user interface description

Concluding Remarks

* History:: History of GNU `gettext'
* References:: Related Readings

File: gettext.info, Node: Introduction, Next: Basics, Prev: Top, Up: Top

1 Introduction
**************

This manual is still in _DRAFT_ state. Some sections are still
empty, or almost. We keep merging material from other sources
(essentially e-mail folders) while the proper integration of this
material is delayed.

In this manual, we use _he_ when speaking of the programmer or
maintainer, _she_ when speaking of the translator, and _they_ when
speaking of the installers or end users of the translated program.
This is only a convenience for clarifying the documentation. It is
_absolutely_ not meant to imply that some roles are more appropriate to
males or females. Besides, as you might guess, GNU `gettext' is meant
to be useful for people using computers, whatever their sex, race,
religion or nationality!

This chapter explains the goals sought in the creation of GNU
`gettext' and the free Translation Project. Then, it explains a few
broad concepts around Native Language Support, and positions message
translation with regard to other aspects of national and cultural
variance, as they apply to to programs. It also surveys those files
used to convey the translations. It explains how the various tools
interact in the initial generation of these files, and later, how the
maintenance cycle should usually operate.

Please send suggestions and corrections to:

Internet address:
bug-gnu-gettext@gnu.org

Please include the manual's edition number and update date in your
messages.

* Menu:

* Why:: The Purpose of GNU `gettext'
* Concepts:: I18n, L10n, and Such
* Aspects:: Aspects in Native Language Support
* Files:: Files Conveying Translations
* Overview:: Overview of GNU `gettext'

File: gettext.info, Node: Why, Next: Concepts, Prev: Introduction, Up: Introduction

1.1 The Purpose of GNU `gettext'
================================

Usually, programs are written and documented in English, and use
English at execution time to interact with users. This is true not
only of GNU software, but also of a great deal of commercial and free
software. Using a common language is quite handy for communication
between developers, maintainers and users from all countries. On the
other hand, most people are less comfortable with English than with
their own native language, and would prefer to use their mother tongue
for day to day's work, as far as possible. Many would simply _love_ to
see their computer screen showing a lot less of English, and far more
of their own language.

However, to many people, this dream might appear so far fetched that
they may believe it is not even worth spending time thinking about it.
They have no confidence at all that the dream might ever become true.
Yet some have not lost hope, and have organized themselves. The
Translation Project is a formalization of this hope into a workable
structure, which has a good chance to get all of us nearer the
achievement of a truly multi-lingual set of programs.

GNU `gettext' is an important step for the Translation Project, as
it is an asset on which we may build many other steps. This package
offers to programmers, translators and even users, a well integrated
set of tools and documentation. Specifically, the GNU `gettext'
utilities are a set of tools that provides a framework within which
other free packages may produce multi-lingual messages. These tools
include

* A set of conventions about how programs should be written to
support message catalogs.

* A directory and file naming organization for the message catalogs
themselves.

* A runtime library supporting the retrieval of translated messages.

* A few stand-alone programs to massage in various ways the sets of
translatable strings, or already translated strings.

* A special mode for Emacs(1) which helps preparing these sets and
bringing them up to date.

GNU `gettext' is designed to minimize the impact of
internationalization on program sources, keeping this impact as small
and hardly noticeable as possible. Internationalization has better
chances of succeeding if it is very light weighted, or at least, appear
to be so, when looking at program sources.

The Translation Project also uses the GNU `gettext' distribution as
a vehicle for documenting its structure and methods. This goes beyond
the strict technicalities of documenting the GNU `gettext' proper. By
so doing, translators will find in a single place, as far as possible,
all they need to know for properly doing their translating work. Also,
this supplemental documentation might also help programmers, and even
curious users, in understanding how GNU `gettext' is related to the
remainder of the Translation Project, and consequently, have a glimpse
at the _big picture_.

---------- Footnotes ----------

(1) In this manual, all mentions of Emacs refers to either GNU Emacs
or to XEmacs, which people sometimes call FSF Emacs and Lucid Emacs,
respectively.

File: gettext.info, Node: Concepts, Next: Aspects, Prev: Why, Up: Introduction

1.2 I18n, L10n, and Such
========================

Two long words appear all the time when we discuss support of native
language in programs, and these words have a precise meaning, worth
being explained here, once and for all in this document. The words are
_internationalization_ and _localization_. Many people, tired of
writing these long words over and over again, took the habit of writing
"i18n" and "l10n" instead, quoting the first and last letter of each
word, and replacing the run of intermediate letters by a number merely
telling how many such letters there are. But in this manual, in the
sake of clarity, we will patiently write the names in full, each time...

By "internationalization", one refers to the operation by which a
program, or a set of programs turned into a package, is made aware of
and able to support multiple languages. This is a generalization
process, by which the programs are untied from calling only English
strings or other English specific habits, and connected to generic ways
of doing the same, instead. Program developers may use various
techniques to internationalize their programs. Some of these have been
standardized. GNU `gettext' offers one of these standards. *Note
Programmers::.

By "localization", one means the operation by which, in a set of
programs already internationalized, one gives the program all needed
information so that it can adapt itself to handle its input and output
in a fashion which is correct for some native language and cultural
habits. This is a particularisation process, by which generic methods
already implemented in an internationalized program are used in
specific ways. The programming environment puts several functions to
the programmers disposal which allow this runtime configuration. The
formal description of specific set of cultural habits for some country,
together with all associated translations targeted to the same native
language, is called the "locale" for this language or country. Users
achieve localization of programs by setting proper values to special
environment variables, prior to executing those programs, identifying
which locale should be used.

In fact, locale message support is only one component of the cultural
data that makes up a particular locale. There are a whole host of
routines and functions provided to aid programmers in developing
internationalized software and which allow them to access the data
stored in a particular locale. When someone presently refers to a
particular locale, they are obviously referring to the data stored
within that particular locale. Similarly, if a programmer is referring
to "accessing the locale routines", they are referring to the complete
suite of routines that access all of the locale's information.

One uses the expression "Native Language Support", or merely NLS,
for speaking of the overall activity or feature encompassing both
internationalization and localization, allowing for multi-lingual
interactions in a program. In a nutshell, one could say that
internationalization is the operation by which further localizations
are made possible.

Also, very roughly said, when it comes to multi-lingual messages,
internationalization is usually taken care of by programmers, and
localization is usually taken care of by translators.

File: gettext.info, Node: Aspects, Next: Files, Prev: Concepts, Up: Introduction

1.3 Aspects in Native Language Support
======================================

For a totally multi-lingual distribution, there are many things to
translate beyond output messages.

* As of today, GNU `gettext' offers a complete toolset for
translating messages output by C programs. Perl scripts and shell
scripts will also need to be translated. Even if there are today
some hooks by which this can be done, these hooks are not
integrated as well as they should be.

* Some programs, like `autoconf' or `bison', are able to produce
other programs (or scripts). Even if the generating programs
themselves are internationalized, the generated programs they
produce may need internationalization on their own, and this
indirect internationalization could be automated right from the
generating program. In fact, quite usually, generating and
generated programs could be internationalized independently, as
the effort needed is fairly orthogonal.

* A few programs include textual tables which might need translation
themselves, independently of the strings contained in the program
itself. For example, RFC 1345 gives an English description for
each character which the `recode' program is able to reconstruct
at execution. Since these descriptions are extracted from the RFC
by mechanical means, translating them properly would require a
prior translation of the RFC itself.

* Almost all programs accept options, which are often worded out so
to be descriptive for the English readers; one might want to
consider offering translated versions for program options as well.

* Many programs read, interpret, compile, or are somewhat driven by
input files which are texts containing keywords, identifiers, or
replies which are inherently translatable. For example, one may
want `gcc' to allow diacriticized characters in identifiers or use
translated keywords; `rm -i' might accept something else than `y'
or `n' for replies, etc. Even if the program will eventually make
most of its output in the foreign languages, one has to decide
whether the input syntax, option values, etc., are to be localized
or not.

* The manual accompanying a package, as well as all documentation
files in the distribution, could surely be translated, too.
Translating a manual, with the intent of later keeping up with
updates, is a major undertaking in itself, generally.

As we already stressed, translation is only one aspect of locales.
Other internationalization aspects are system services and are handled
in GNU `libc'. There are many attributes that are needed to define a
country's cultural conventions. These attributes include beside the
country's native language, the formatting of the date and time, the
representation of numbers, the symbols for currency, etc. These local
"rules" are termed the country's locale. The locale represents the
knowledge needed to support the country's native attributes.

There are a few major areas which may vary between countries and
hence, define what a locale must describe. The following list helps
putting multi-lingual messages into the proper context of other tasks
related to locales. See the GNU `libc' manual for details.

_Characters and Codesets_
The codeset most commonly used through out the USA and most English
speaking parts of the world is the ASCII codeset. However, there
are many characters needed by various locales that are not found
within this codeset. The 8-bit ISO 8859-1 code set has most of
the special characters needed to handle the major European
languages. However, in many cases, choosing ISO 8859-1 is
nevertheless not adequate: it doesn't even handle the major
European currency. Hence each locale will need to specify which
codeset they need to use and will need to have the appropriate
character handling routines to cope with the codeset.

_Currency_
The symbols used vary from country to country as does the position
used by the symbol. Software needs to be able to transparently
display currency figures in the native mode for each locale.

_Dates_
The format of date varies between locales. For example, Christmas
day in 1994 is written as 12/25/94 in the USA and as 25/12/94 in
Australia. Other countries might use ISO 8601 dates, etc.

Time of the day may be noted as HH:MM, HH.MM, or otherwise. Some
locales require time to be specified in 24-hour mode rather than
as AM or PM. Further, the nature and yearly extent of the
Daylight Saving correction vary widely between countries.

_Numbers_
Numbers can be represented differently in different locales. For
example, the following numbers are all written correctly for their
respective locales:

12,345.67 English
12.345,67 German
12345,67 French
1,2345.67 Asia

Some programs could go further and use different unit systems, like
English units or Metric units, or even take into account variants
about how numbers are spelled in full.

_Messages_
The most obvious area is the language support within a locale.
This is where GNU `gettext' provides the means for developers and
users to easily change the language that the software uses to
communicate to the user.

Components of locale outside of message handling are standardized in
the ISO C standard and the SUSV2 specification. GNU `libc' fully
implements this, and most other modern systems provide a more or less
reasonable support for at least some of the missing components.

File: gettext.info, Node: Files, Next: Overview, Prev: Aspects, Up: Introduction

1.4 Files Conveying Translations
================================

The letters PO in `.po' files means Portable Object, to distinguish it
from `.mo' files, where MO stands for Machine Object. This paradigm,
as well as the PO file format, is inspired by the NLS standard
developed by Uniforum, and first implemented by Sun in their Solaris
system.

PO files are meant to be read and edited by humans, and associate
each original, translatable string of a given package with its
translation in a particular target language. A single PO file is
dedicated to a single target language. If a package supports many
languages, there is one such PO file per language supported, and each
package has its own set of PO files. These PO files are best created by
the `xgettext' program, and later updated or refreshed through the
`msgmerge' program. Program `xgettext' extracts all marked messages
from a set of C files and initializes a PO file with empty
translations. Program `msgmerge' takes care of adjusting PO files
between releases of the corresponding sources, commenting obsolete
entries, initializing new ones, and updating all source line
references. Files ending with `.pot' are kind of base translation
files found in distributions, in PO file format.

MO files are meant to be read by programs, and are binary in nature.
A few systems already offer tools for creating and handling MO files as
part of the Native Language Support coming with the system, but the
format of these MO files is often different from system to system, and
non-portable. The tools already provided with these systems don't
support all the features of GNU `gettext'. Therefore GNU `gettext'
uses its own format for MO files. Files ending with `.gmo' are really
MO files, when it is known that these files use the GNU format.

File: gettext.info, Node: Overview, Prev: Files, Up: Introduction

1.5 Overview of GNU `gettext'
=============================

The following diagram summarizes the relation between the files handled
by GNU `gettext' and the tools acting on these files. It is followed
by somewhat detailed explanations, which you should read while keeping
an eye on the diagram. Having a clear understanding of these
interrelations will surely help programmers, translators and
maintainers.

The indication `PO mode' appears in two places in this picture, and
you may safely read it as merely meaning "hand editing", using any
editor of your choice, really. However, for those of you being the
lucky users of Emacs, PO mode has been specifically created for
providing a cozy environment for editing or modifying PO files. While
editing a PO file, PO mode allows for the easy browsing of auxiliary
and compendium PO files, as well as for following references into the
set of C program sources from which PO files have been derived. It has
a few special features, among which are the interactive marking of
program strings as translatable, and the validation of PO files with
easy repositioning to PO file lines showing errors.

As a programmer, the first step to bringing GNU `gettext' into your
package is identifying, right in the C sources, those strings which are
meant to be translatable, and those which are untranslatable. This
tedious job can be done a little more comfortably using emacs PO mode,
but you can use any means familiar to you for modifying your C sources.
Beside this some other simple, standard changes are needed to properly
initialize the translation library. *Note Sources::, for more
information about all this.

For newly written software the strings of course can and should be
marked while writing it. The `gettext' approach makes this very easy.
Simply put the following lines at the beginning of each file or in a
central header file:

#define _(String) (String)
#define N_(String) String
#define textdomain(Domain)
#define bindtextdomain(Package, Directory)

Doing this allows you to prepare the sources for internationalization.
Later when you feel ready for the step to use the `gettext' library
simply replace these definitions by the following:

#include <libintl.h>
#define _(String) gettext (String)
#define gettext_noop(String) String
#define N_(String) gettext_noop (String)

and link against `libintl.a' or `libintl.so'. Note that on GNU
systems, you don't need to link with `libintl' because the `gettext'
library functions are already contained in GNU libc. That is all you
have to change.

Once the C sources have been modified, the `xgettext' program is
used to find and extract all translatable strings, and create a PO
template file out of all these. This `PACKAGE.pot' file contains all
original program strings. It has sets of pointers to exactly where in
C sources each string is used. All translations are set to empty. The
letter `t' in `.pot' marks this as a Template PO file, not yet oriented
towards any particular language. *Note xgettext Invocation::, for more
details about how one calls the `xgettext' program. If you are
_really_ lazy, you might be interested at working a lot more right
away, and preparing the whole distribution setup (*note Maintainers::).
By doing so, you spare yourself typing the `xgettext' command, as
`make' should now generate the proper things automatically for you!

The first time through, there is no `LANG.po' yet, so the `msgmerge'
step may be skipped and replaced by a mere copy of `PACKAGE.pot' to
`LANG.po', where LANG represents the target language. See *Note
Creating:: for details.

Then comes the initial translation of messages. Translation in
itself is a whole matter, still exclusively meant for humans, and whose
complexity far overwhelms the level of this manual. Nevertheless, a
few hints are given in some other chapter of this manual (*note
Translators::). You will also find there indications about how to
contact translating teams, or becoming part of them, for sharing your
translating concerns with others who target the same native language.

While adding the translated messages into the `LANG.po' PO file, if
you do not have Emacs handy, you are on your own for ensuring that your
efforts fully respect the PO file format, and quoting conventions
(*note PO Files::). This is surely not an impossible task, as this is
the way many people have handled PO files already for Uniforum or
Solaris. On the other hand, by using PO mode in Emacs, most details of
PO file format are taken care of for you, but you have to acquire some
familiarity with PO mode itself. Besides main PO mode commands (*note
Main PO Commands::), you should know how to move between entries (*note
Entry Positioning::), and how to handle untranslated entries (*note
Untranslated Entries::).

If some common translations have already been saved into a compendium
PO file, translators may use PO mode for initializing untranslated
entries from the compendium, and also save selected translations into
the compendium, updating it (*note Compendium::). Compendium files are
meant to be exchanged between members of a given translation team.

Programs, or packages of programs, are dynamic in nature: users write
bug reports and suggestion for improvements, maintainers react by
modifying programs in various ways. The fact that a package has
already been internationalized should not make maintainers shy of
adding new strings, or modifying strings already translated. They just
do their job the best they can. For the Translation Project to work
smoothly, it is important that maintainers do not carry translation
concerns on their already loaded shoulders, and that translators be
kept as free as possible of programming concerns.

The only concern maintainers should have is carefully marking new
strings as translatable, when they should be, and do not otherwise
worry about them being translated, as this will come in proper time.
Consequently, when programs and their strings are adjusted in various
ways by maintainers, and for matters usually unrelated to translation,
`xgettext' would construct `PACKAGE.pot' files which are evolving over
time, so the translations carried by `LANG.po' are slowly fading out of
date.

It is important for translators (and even maintainers) to understand
that package translation is a continuous process in the lifetime of a
package, and not something which is done once and for all at the start.
After an initial burst of translation activity for a given package,
interventions are needed once in a while, because here and there,
translated entries become obsolete, and new untranslated entries
appear, needing translation.

The `msgmerge' program has the purpose of refreshing an already
existing `LANG.po' file, by comparing it with a newer `PACKAGE.pot'
template file, extracted by `xgettext' out of recent C sources. The
refreshing operation adjusts all references to C source locations for
strings, since these strings move as programs are modified. Also,
`msgmerge' comments out as obsolete, in `LANG.po', those already
translated entries which are no longer used in the program sources
(*note Obsolete Entries::). It finally discovers new strings and
inserts them in the resulting PO file as untranslated entries (*note
Untranslated Entries::). *Note msgmerge Invocation::, for more
information about what `msgmerge' really does.

Whatever route or means taken, the goal is to obtain an updated
`LANG.po' file offering translations for all strings.

The temporal mobility, or fluidity of PO files, is an integral part
of the translation game, and should be well understood, and accepted.
People resisting it will have a hard time participating in the
Translation Project, or will give a hard time to other participants! In
particular, maintainers should relax and include all available official
PO files in their distributions, even if these have not recently been
updated, without exerting pressure on the translator teams to get the
job done. The pressure should rather come from the community of users
speaking a particular language, and maintainers should consider
themselves fairly relieved of any concern about the adequacy of
translation files. On the other hand, translators should reasonably
try updating the PO files they are responsible for, while the package
is undergoing pretest, prior to an official distribution.

Once the PO file is complete and dependable, the `msgfmt' program is
used for turning the PO file into a machine-oriented format, which may
yield efficient retrieval of translations by the programs of the
package, whenever needed at runtime (*note MO Files::). *Note msgfmt
Invocation::, for more information about all modes of execution for the
`msgfmt' program.

Finally, the modified and marked C sources are compiled and linked
with the GNU `gettext' library, usually through the operation of
`make', given a suitable `Makefile' exists for the project, and the
resulting executable is installed somewhere users will find it. The MO
files themselves should also be properly installed. Given the
appropriate environment variables are set (*note End Users::), the
program should localize itself automatically, whenever it executes.

The remainder of this manual has the purpose of explaining in depth
the various steps outlined above.

File: gettext.info, Node: Basics, Next: Sources, Prev: Introduction, Up: Top

2 PO Files and PO Mode Basics
*****************************

The GNU `gettext' toolset helps programmers and translators at
producing, updating and using translation files, mainly those PO files
which are textual, editable files. This chapter stresses the format of
PO files, and contains a PO mode starter. PO mode description is
spread throughout this manual instead of being concentrated in one
place. Here we present only the basics of PO mode.

* Menu:

File: gettext.info, Node: Installation, Next: PO Files, Prev: Basics, Up: Basics

2.1 Completing GNU `gettext' Installation
=========================================

Once you have received, unpacked, configured and compiled the GNU
`gettext' distribution, the `make install' command puts in place the
programs `xgettext', `msgfmt', `gettext', and `msgmerge', as well as
their available message catalogs. To top off a comfortable
installation, you might also want to make the PO mode available to your
Emacs users.

During the installation of the PO mode, you might want to modify your
file `.emacs', once and for all, so it contains a few lines looking
like:

(setq auto-mode-alist
(cons '("\\.po\\'\\|\\.po\\." . po-mode) auto-mode-alist))
(autoload 'po-mode "po-mode" "Major mode for translators to edit PO files" t)

Later, whenever you edit some `.po' file, or any file having the
string `.po.' within its name, Emacs loads `po-mode.elc' (or
`po-mode.el') as needed, and automatically activates PO mode commands
for the associated buffer. The string _PO_ appears in the mode line
for any buffer for which PO mode is active. Many PO files may be
active at once in a single Emacs session.

If you are using Emacs version 20 or newer, and have already
installed the appropriate international fonts on your system, you may
also tell Emacs how to determine automatically the coding system of
every PO file. This will often (but not always) cause the necessary
fonts to be loaded and used for displaying the translations on your
Emacs screen. For this to happen, add the lines:

(modify-coding-system-alist 'file "\\.po\\'\\|\\.po\\."
'po-find-file-coding-system)
(autoload 'po-find-file-coding-system "po-mode")

to your `.emacs' file. If, with this, you still see boxes instead of
international characters, try a different font set (via Shift Mouse
button 1).

File: gettext.info, Node: PO Files, Next: Main PO Commands, Prev: Installation, Up: Basics

2.2 The Format of PO Files
==========================

A PO file is made up of many entries, each entry holding the relation
between an original untranslated string and its corresponding
translation. All entries in a given PO file usually pertain to a
single project, and all translations are expressed in a single target
language. One PO file "entry" has the following schematic structure:

WHITE-SPACE
# TRANSLATOR-COMMENTS
#. AUTOMATIC-COMMENTS
#: REFERENCE...
#, FLAG...
msgid UNTRANSLATED-STRING
msgstr TRANSLATED-STRING

The general structure of a PO file should be well understood by the
translator. When using PO mode, very little has to be known about the
format details, as PO mode takes care of them for her.

A simple entry can look like this:

#: lib/error.c:116
msgid "Unknown system error"
msgstr "Error desconegut del sistema"

Entries begin with some optional white space. Usually, when
generated through GNU `gettext' tools, there is exactly one blank line
between entries. Then comments follow, on lines all starting with the
character `#'. There are two kinds of comments: those which have some
white space immediately following the `#', which comments are created
and maintained exclusively by the translator, and those which have some
non-white character just after the `#', which comments are created and
maintained automatically by GNU `gettext' tools. All comments, of
either kind, are optional.

After white space and comments, entries show two strings, namely
first the untranslated string as it appears in the original program
sources, and then, the translation of this string. The original string
is introduced by the keyword `msgid', and the translation, by `msgstr'.
The two strings, untranslated and translated, are quoted in various
ways in the PO file, using `"' delimiters and `\' escapes, but the
translator does not really have to pay attention to the precise quoting
format, as PO mode fully takes care of quoting for her.

The `msgid' strings, as well as automatic comments, are produced and
managed by other GNU `gettext' tools, and PO mode does not provide
means for the translator to alter these. The most she can do is merely
deleting them, and only by deleting the whole entry. On the other
hand, the `msgstr' string, as well as translator comments, are really
meant for the translator, and PO mode gives her the full control she
needs.

The comment lines beginning with `#,' are special because they are
not completely ignored by the programs as comments generally are. The
comma separated list of FLAGs is used by the `msgfmt' program to give
the user some better diagnostic messages. Currently there are two
forms of flags defined:

`fuzzy'
This flag can be generated by the `msgmerge' program or it can be
inserted by the translator herself. It shows that the `msgstr'
string might not be a correct translation (anymore). Only the
translator can judge if the translation requires further
modification, or is acceptable as is. Once satisfied with the
translation, she then removes this `fuzzy' attribute. The
`msgmerge' program inserts this when it combined the `msgid' and
`msgstr' entries after fuzzy search only. *Note Fuzzy Entries::.

`c-format'
`no-c-format'
These flags should not be added by a human. Instead only the
`xgettext' program adds them. In an automated PO file processing
system as proposed here the user changes would be thrown away
again as soon as the `xgettext' program generates a new template
file.

The `c-format' flag tells that the untranslated string and the
translation are supposed to be C format strings. The `no-c-format'
flag tells that they are not C format strings, even though the
untranslated string happens to look like a C format string (with
`%' directives).

In case the `c-format' flag is given for a string the `msgfmt'
does some more tests to check to validity of the translation.
*Note msgfmt Invocation::, *Note c-format Flag:: and *Note
c-format::.

`objc-format'
`no-objc-format'
Likewise for Objective C, see *Note objc-format::.

`sh-format'
`no-sh-format'
Likewise for Shell, see *Note sh-format::.

`python-format'
`no-python-format'
Likewise for Python, see *Note python-format::.

`lisp-format'
`no-lisp-format'
Likewise for Lisp, see *Note lisp-format::.

`elisp-format'
`no-elisp-format'
Likewise for Emacs Lisp, see *Note elisp-format::.

`librep-format'
`no-librep-format'
Likewise for librep, see *Note librep-format::.

`scheme-format'
`no-scheme-format'
Likewise for Scheme, see *Note scheme-format::.

`smalltalk-format'
`no-smalltalk-format'
Likewise for Smalltalk, see *Note smalltalk-format::.

`java-format'
`no-java-format'
Likewise for Java, see *Note java-format::.

`csharp-format'
`no-csharp-format'
Likewise for C#, see *Note csharp-format::.

`awk-format'
`no-awk-format'
Likewise for awk, see *Note awk-format::.

`object-pascal-format'
`no-object-pascal-format'
Likewise for Object Pascal, see *Note object-pascal-format::.

`ycp-format'
`no-ycp-format'
Likewise for YCP, see *Note ycp-format::.

`tcl-format'
`no-tcl-format'
Likewise for Tcl, see *Note tcl-format::.

`perl-format'
`no-perl-format'
Likewise for Perl, see *Note perl-format::.

`perl-brace-format'
`no-perl-brace-format'
Likewise for Perl brace, see *Note perl-format::.

`php-format'
`no-php-format'
Likewise for PHP, see *Note php-format::.

`gcc-internal-format'
`no-gcc-internal-format'
Likewise for the GCC sources, see *Note gcc-internal-format::.

`qt-format'
`no-qt-format'
Likewise for Qt, see *Note qt-format::.

A different kind of entries is used for translations which involve
plural forms.

WHITE-SPACE
# TRANSLATOR-COMMENTS
#. AUTOMATIC-COMMENTS
#: REFERENCE...
#, FLAG...
msgid UNTRANSLATED-STRING-SINGULAR
msgid_plural UNTRANSLATED-STRING-PLURAL
msgstr[0] TRANSLATED-STRING-CASE-0
...
msgstr[N] TRANSLATED-STRING-CASE-N

Such an entry can look like this:

#: src/msgcmp.c:338 src/po-lex.c:699
#, c-format
msgid "found %d fatal error"
msgid_plural "found %d fatal errors"
msgstr[0] "s'ha trobat %d error fatal"
msgstr[1] "s'han trobat %d errors fatals"

It happens that some lines, usually whitespace or comments, follow
the very last entry of a PO file. Such lines are not part of any entry,
and PO mode is unable to take action on those lines. By using the PO
mode function `M-x po-normalize', the translator may get rid of those
spurious lines. *Note Normalizing::.

The remainder of this section may be safely skipped by those using
PO mode, yet it may be interesting for everybody to have a better idea
of the precise format of a PO file. On the other hand, those not
having Emacs handy should carefully continue reading on.

Each of UNTRANSLATED-STRING and TRANSLATED-STRING respects the C
syntax for a character string, including the surrounding quotes and
embedded backslashed escape sequences. When the time comes to write
multi-line strings, one should not use escaped newlines. Instead, a
closing quote should follow the last character on the line to be
continued, and an opening quote should resume the string at the
beginning of the following PO file line. For example:

msgid ""
"Here is an example of how one might continue a very long string\n"
"for the common case the string represents multi-line output.\n"

In this example, the empty string is used on the first line, to allow
better alignment of the `H' from the word `Here' over the `f' from the
word `for'. In this example, the `msgid' keyword is followed by three
strings, which are meant to be concatenated. Concatenating the empty
string does not change the resulting overall string, but it is a way
for us to comply with the necessity of `msgid' to be followed by a
string on the same line, while keeping the multi-line presentation
left-justified, as we find this to be a cleaner disposition. The empty
string could have been omitted, but only if the string starting with
`Here' was promoted on the first line, right after `msgid'.(1) It was
not really necessary either to switch between the two last quoted
strings immediately after the newline `\n', the switch could have
occurred after _any_ other character, we just did it this way because
it is neater.

One should carefully distinguish between end of lines marked as `\n'
_inside_ quotes, which are part of the represented string, and end of
lines in the PO file itself, outside string quotes, which have no
incidence on the represented string.

Outside strings, white lines and comments may be used freely.
Comments start at the beginning of a line with `#' and extend until the
end of the PO file line. Comments written by translators should have
the initial `#' immediately followed by some white space. If the `#'
is not immediately followed by white space, this comment is most likely
generated and managed by specialized GNU tools, and might disappear or
be replaced unexpectedly when the PO file is given to `msgmerge'.

---------- Footnotes ----------

(1) This limitation is not imposed by GNU `gettext', but is for
compatibility with the `msgfmt' implementation on Solaris.

File: gettext.info, Node: Main PO Commands, Next: Entry Positioning, Prev: PO Files, Up: Basics

2.3 Main PO mode Commands
=========================

After setting up Emacs with something similar to the lines in *Note
Installation::, PO mode is activated for a window when Emacs finds a PO
file in that window. This puts the window read-only and establishes a
po-mode-map, which is a genuine Emacs mode, in a way that is not derived
from text mode in any way. Functions found on `po-mode-hook', if any,
will be executed.

When PO mode is active in a window, the letters `PO' appear in the
mode line for that window. The mode line also displays how many
entries of each kind are held in the PO file. For example, the string
`132t+3f+10u+2o' would tell the translator that the PO mode contains
132 translated entries (*note Translated Entries::, 3 fuzzy entries
(*note Fuzzy Entries::), 10 untranslated entries (*note Untranslated
Entries::) and 2 obsolete entries (*note Obsolete Entries::).
Zero-coefficients items are not shown. So, in this example, if the
fuzzy entries were unfuzzied, the untranslated entries were translated
and the obsolete entries were deleted, the mode line would merely
display `145t' for the counters.

The main PO commands are those which do not fit into the other
categories of subsequent sections. These allow for quitting PO mode or
for managing windows in special ways.

`_'
Undo last modification to the PO file (`po-undo').

`Q'
Quit processing and save the PO file (`po-quit').

`q'
Quit processing, possibly after confirmation
(`po-confirm-and-quit').

`0'
Temporary leave the PO file window (`po-other-window').

`?'
`h'
Show help about PO mode (`po-help').

`='
Give some PO file statistics (`po-statistics').

`V'
Batch validate the format of the whole PO file (`po-validate').

The command `_' (`po-undo') interfaces to the Emacs _undo_ facility.
*Note Undoing Changes: (emacs)Undo. Each time `U' is typed,
modifications which the translator did to the PO file are undone a
little more. For the purpose of undoing, each PO mode command is
atomic. This is especially true for the `<RET>' command: the whole
edition made by using a single use of this command is undone at once,
even if the edition itself implied several actions. However, while in
the editing window, one can undo the edition work quite parsimoniously.

The commands `Q' (`po-quit') and `q' (`po-confirm-and-quit') are
used when the translator is done with the PO file. The former is a bit
less verbose than the latter. If the file has been modified, it is
saved to disk first. In both cases, and prior to all this, the
commands check if any untranslated messages remain in the PO file and,
if so, the translator is asked if she really wants to leave off working
with this PO file. This is the preferred way of getting rid of an
Emacs PO file buffer. Merely killing it through the usual command
`C-x k' (`kill-buffer') is not the tidiest way to proceed.

The command `0' (`po-other-window') is another, softer way, to leave
PO mode, temporarily. It just moves the cursor to some other Emacs
window, and pops one if necessary. For example, if the translator just
got PO mode to show some source context in some other, she might
discover some apparent bug in the program source that needs correction.
This command allows the translator to change sex, become a programmer,
and have the cursor right into the window containing the program she
(or rather _he_) wants to modify. By later getting the cursor back in
the PO file window, or by asking Emacs to edit this file once again, PO
mode is then recovered.

The command `h' (`po-help') displays a summary of all available PO
mode commands. The translator should then type any character to resume
normal PO mode operations. The command `?' has the same effect as `h'.

The command `=' (`po-statistics') computes the total number of
entries in the PO file, the ordinal of the current entry (counted from
1), the number of untranslated entries, the number of obsolete entries,
and displays all these numbers.

The command `V' (`po-validate') launches `msgfmt' in checking and
verbose mode over the current PO file. This command first offers to
save the current PO file on disk. The `msgfmt' tool, from GNU
`gettext', has the purpose of creating a MO file out of a PO file, and
PO mode uses the features of this program for checking the overall
format of a PO file, as well as all individual entries.

The program `msgfmt' runs asynchronously with Emacs, so the
translator regains control immediately while her PO file is being
studied. Error output is collected in the Emacs `*compilation*' buffer,
displayed in another window. The regular Emacs command `C-x`'
(`next-error'), as well as other usual compile commands, allow the
translator to reposition quickly to the offending parts of the PO file.
Once the cursor is on the line in error, the translator may decide on
any PO mode action which would help correcting the error.

File: gettext.info, Node: Entry Positioning, Next: Normalizing, Prev: Main PO Commands, Up: Basics

2.4 Entry Positioning
=====================

The cursor in a PO file window is almost always part of an entry. The
only exceptions are the special case when the cursor is after the last
entry in the file, or when the PO file is empty. The entry where the
cursor is found to be is said to be the current entry. Many PO mode
commands operate on the current entry, so moving the cursor does more
than allowing the translator to browse the PO file, this also selects
on which entry commands operate.

Some PO mode commands alter the position of the cursor in a
specialized way. A few of those special purpose positioning are
described here, the others are described in following sections (for a
complete list try `C-h m'):

`.'
Redisplay the current entry (`po-current-entry').

`n'
Select the entry after the current one (`po-next-entry').

`p'
Select the entry before the current one (`po-previous-entry').

`<'
Select the first entry in the PO file (`po-first-entry').

`>'
Select the last entry in the PO file (`po-last-entry').

`m'
Record the location of the current entry for later use
(`po-push-location').

`r'
Return to a previously saved entry location (`po-pop-location').

`x'
Exchange the current entry location with the previously saved one
(`po-exchange-location').

Any Emacs command able to reposition the cursor may be used to
select the current entry in PO mode, including commands which move by
characters, lines, paragraphs, screens or pages, and search commands.
However, there is a kind of standard way to display the current entry
in PO mode, which usual Emacs commands moving the cursor do not
especially try to enforce. The command `.' (`po-current-entry') has
the sole purpose of redisplaying the current entry properly, after the
current entry has been changed by means external to PO mode, or the
Emacs screen otherwise altered.

It is yet to be decided if PO mode helps the translator, or otherwise
irritates her, by forcing a rigid window disposition while she is doing
her work. We originally had quite precise ideas about how windows
should behave, but on the other hand, anyone used to Emacs is often
happy to keep full control. Maybe a fixed window disposition might be
offered as a PO mode option that the translator might activate or
deactivate at will, so it could be offered on an experimental basis.
If nobody feels a real need for using it, or a compulsion for writing
it, we should drop this whole idea. The incentive for doing it should
come from translators rather than programmers, as opinions from an
experienced translator are surely more worth to me than opinions from
programmers _thinking_ about how _others_ should do translation.

The commands `n' (`po-next-entry') and `p' (`po-previous-entry')
move the cursor the entry following, or preceding, the current one. If
`n' is given while the cursor is on the last entry of the PO file, or
if `p' is given while the cursor is on the first entry, no move is done.

The commands `<' (`po-first-entry') and `>' (`po-last-entry') move
the cursor to the first entry, or last entry, of the PO file. When the
cursor is located past the last entry in a PO file, most PO mode
commands will return an error saying `After last entry'. Moreover, the
commands `<' and `>' have the special property of being able to work
even when the cursor is not into some PO file entry, and one may use
them for nicely correcting this situation. But even these commands
will fail on a truly empty PO file. There are development plans for
the PO mode for it to interactively fill an empty PO file from sources.
*Note Marking::.

The translator may decide, before working at the translation of a
particular entry, that she needs to browse the remainder of the PO
file, maybe for finding the terminology or phraseology used in related
entries. She can of course use the standard Emacs idioms for saving
the current cursor location in some register, and use that register for
getting back, or else, use the location ring.

PO mode offers another approach, by which cursor locations may be
saved onto a special stack. The command `m' (`po-push-location')
merely adds the location of current entry to the stack, pushing the
already saved locations under the new one. The command `r'
(`po-pop-location') consumes the top stack element and repositions the
cursor to the entry associated with that top element. This position is
then lost, for the next `r' will move the cursor to the previously
saved location, and so on until no locations remain on the stack.

If the translator wants the position to be kept on the location
stack, maybe for taking a look at the entry associated with the top
element, then go elsewhere with the intent of getting back later, she
ought to use `m' immediately after `r'.

The command `x' (`po-exchange-location') simultaneously repositions
the cursor to the entry associated with the top element of the stack of
saved locations, and replaces that top element with the location of the
current entry before the move. Consequently, repeating the `x' command
toggles alternatively between two entries. For achieving this, the
translator will position the cursor on the first entry, use `m', then
position to the second entry, and merely use `x' for making the switch.

File: gettext.info, Node: Normalizing, Prev: Entry Positioning, Up: Basics

2.5 Normalizing Strings in Entries
==================================

There are many different ways for encoding a particular string into a
PO file entry, because there are so many different ways to split and
quote multi-line strings, and even, to represent special characters by
backslashed escaped sequences. Some features of PO mode rely on the
ability for PO mode to scan an already existing PO file for a
particular string encoded into the `msgid' field of some entry. Even
if PO mode has internally all the built-in machinery for implementing
this recognition easily, doing it fast is technically difficult. To
facilitate a solution to this efficiency problem, we decided on a
canonical representation for strings.

A conventional representation of strings in a PO file is currently
under discussion, and PO mode experiments with a canonical
representation. Having both `xgettext' and PO mode converging towards
a uniform way of representing equivalent strings would be useful, as
the internal normalization needed by PO mode could be automatically
satisfied when using `xgettext' from GNU `gettext'. An explicit PO
mode normalization should then be only necessary for PO files imported
from elsewhere, or for when the convention itself evolves.

So, for achieving normalization of at least the strings of a given
PO file needing a canonical representation, the following PO mode
command is available:

`M-x po-normalize'
Tidy the whole PO file by making entries more uniform.

The special command `M-x po-normalize', which has no associated
keys, revises all entries, ensuring that strings of both original and
translated entries use uniform internal quoting in the PO file. It
also removes any crumb after the last entry. This command may be
useful for PO files freshly imported from elsewhere, or if we ever
improve on the canonical quoting format we use. This canonical format
is not only meant for getting cleaner PO files, but also for greatly
speeding up `msgid' string lookup for some other PO mode commands.

`M-x po-normalize' presently makes three passes over the entries.
The first implements heuristics for converting PO files for GNU
`gettext' 0.6 and earlier, in which `msgid' and `msgstr' fields were
using K&R style C string syntax for multi-line strings. These
heuristics may fail for comments not related to obsolete entries and
ending with a backslash; they also depend on subsequent passes for
finalizing the proper commenting of continued lines for obsolete
entries. This first pass might disappear once all oldish PO files
would have been adjusted. The second and third pass normalize all
`msgid' and `msgstr' strings respectively. They also clean out those
trailing backslashes used by XView's `msgfmt' for continued lines.

Having such an explicit normalizing command allows for importing PO
files from other sources, but also eases the evolution of the current
convention, evolution driven mostly by aesthetic concerns, as of now.
It is easy to make suggested adjustments at a later time, as the
normalizing command and eventually, other GNU `gettext' tools should
greatly automate conformance. A description of the canonical string
format is given below, for the particular benefit of those not having
Emacs handy, and who would nevertheless want to handcraft their PO
files in nice ways.

Right now, in PO mode, strings are single line or multi-line. A
string goes multi-line if and only if it has _embedded_ newlines, that
is, if it matches `[^\n]\n+[^\n]'. So, we would have:

msgstr "\n\nHello, world!\n\n\n"

but, replacing the space by a newline, this becomes:

msgstr ""
"\n"
"\n"
"Hello,\n"
"world!\n"
"\n"
"\n"

We are deliberately using a caricatural example, here, to make the
point clearer. Usually, multi-lines are not that bad looking. It is
probable that we will implement the following suggestion. We might
lump together all initial newlines into the empty string, and also all
newlines introducing empty lines (that is, for N > 1, the N-1'th last
newlines would go together on a separate string), so making the
previous example appear:

msgstr "\n\n"
"Hello,\n"
"world!\n"
"\n\n"

There are a few yet undecided little points about string
normalization, to be documented in this manual, once these questions
settle.

File: gettext.info, Node: Sources, Next: Template, Prev: Basics, Up: Top

3 Preparing Program Sources
***************************

For the programmer, changes to the C source code fall into three
categories. First, you have to make the localization functions known
to all modules needing message translation. Second, you should
properly trigger the operation of GNU `gettext' when the program
initializes, usually from the `main' function. Last, you should
identify and especially mark all constant strings in your program
needing translation.

Presuming that your set of programs, or package, has been adjusted
so all needed GNU `gettext' files are available, and your `Makefile'
files are adjusted (*note Maintainers::), each C module having
translated C strings should contain the line:

#include <libintl.h>

Similarly, each C module containing `printf()'/`fprintf()'/...
calls with a format string that could be a translated C string (even if
the C string comes from a different C module) should contain the line:

#include <libintl.h>

The remaining changes to your C sources are discussed in the further
sections of this chapter.

* Menu:

File: gettext.info, Node: Triggering, Next: Preparing Strings, Prev: Sources, Up: Sources

3.1 Triggering `gettext' Operations
===================================

The initialization of locale data should be done with more or less the
same code in every program, as demonstrated below:

int
main (int argc, char *argv[])
{
...
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
...
}

PACKAGE and LOCALEDIR should be provided either by `config.h' or by
the Makefile. For now consult the `gettext' or `hello' sources for
more information.

The use of `LC_ALL' might not be appropriate for you. `LC_ALL'
includes all locale categories and especially `LC_CTYPE'. This later
category is responsible for determining character classes with the
`isalnum' etc. functions from `ctype.h' which could especially for
programs, which process some kind of input language, be wrong. For
example this would mean that a source code using the c, (c-cedilla
character) is runnable in France but not in the U.S.

Some systems also have problems with parsing numbers using the
`scanf' functions if an other but the `LC_ALL' locale is used. The
standards say that additional formats but the one known in the `"C"'
locale might be recognized. But some systems seem to reject numbers in
the `"C"' locale format. In some situation, it might also be a problem
with the notation itself which makes it impossible to recognize whether
the number is in the `"C"' locale or the local format. This can happen
if thousands separator characters are used. Some locales define this
character according to the national conventions to `'.'' which is the
same character used in the `"C"' locale to denote the decimal point.

So it is sometimes necessary to replace the `LC_ALL' line in the
code above by a sequence of `setlocale' lines

{
...
setlocale (LC_CTYPE, "");
setlocale (LC_MESSAGES, "");
...
}

On all POSIX conformant systems the locale categories `LC_CTYPE',
`LC_MESSAGES', `LC_COLLATE', `LC_MONETARY', `LC_NUMERIC', and `LC_TIME'
are available. On some systems which are only ISO C compliant,
`LC_MESSAGES' is missing, but a substitute for it is defined in GNU
gettext's `<libintl.h>'.

Note that changing the `LC_CTYPE' also affects the functions
declared in the `<ctype.h>' standard header. If this is not desirable
in your application (for example in a compiler's parser), you can use a
set of substitute functions which hardwire the C locale, such as found
in the `<c-ctype.h>' and `<c-ctype.c>' files in the gettext source
distribution.

It is also possible to switch the locale forth and back between the
environment dependent locale and the C locale, but this approach is
normally avoided because a `setlocale' call is expensive, because it is
tedious to determine the places where a locale switch is needed in a
large program's source, and because switching a locale is not
multithread-safe.

File: gettext.info, Node: Preparing Strings, Next: Mark Keywords, Prev: Triggering, Up: Sources

3.2 Preparing Translatable Strings
==================================

Before strings can be marked for translations, they sometimes need to
be adjusted. Usually preparing a string for translation is done right
before marking it, during the marking phase which is described in the
next sections. What you have to keep in mind while doing that is the
following.

* Decent English style.

* Entire sentences.

* Split at paragraphs.

* Use format strings instead of string concatenation.

Let's look at some examples of these guidelines.

Translatable strings should be in good English style. If slang
language with abbreviations and shortcuts is used, often translators
will not understand the message and will produce very inappropriate
translations.

"%s: is parameter\n"

This is nearly untranslatable: Is the displayed item _a_ parameter or
_the_ parameter?

"No match"

The ambiguity in this message makes it ununderstandable: Is the program
attempting to set something on fire? Does it mean "The given object does
not match the template"? Does it mean "The template does not fit for any
of the objects"?

In both cases, adding more words to the message will help both the
translator and the English speaking user.

Translatable strings should be entire sentences. It is often not
possible to translate single verbs or adjectives in a substitutable way.

printf ("File %s is %s protected", filename, rw ? "write" : "read");

Most translators will not look at the source and will thus only see the
string `"File %s is %s protected"', which is unintelligible. Change
this to

printf (rw ? "File %s is write protected" : "File %s is read protected",
filename);

This way the translator will not only understand the message, she will
also be able to find the appropriate grammatical construction. The
French translator for example translates "write protected" like
"protected against writing".

Entire sentences are also important because in many languages, the
declination of some word in a sentence depends on the gender or the
number (singular/plural) of another part of the sentence. There are
usually more interdependencies between words than in English. The
consequence is that asking a translator to translate two half-sentences
and then combining these two half-sentences through dumb string
concatenation will not work, for many languages, even though it would
work for English. That's why translators need to handle entire
sentences.

Often sentences don't fit into a single line. If a sentence is
output using two subsequent `printf' statements, like this

printf ("Locale charset \"%s\" is different from\n", lcharset);
printf ("input file charset \"%s\".\n", fcharset);

the translator would have to translate two half sentences, but nothing
in the POT file would tell her that the two half sentences belong
together. It is necessary to merge the two `printf' statements so that
the translator can handle the entire sentence at once and decide at
which place to insert a line break in the translation (if at all):

printf ("Locale charset \"%s\" is different from\n\
input file charset \"%s\".\n", lcharset, fcharset);

You may now ask: how about two or more adjacent sentences? Like in
this case:

puts ("Apollo 13 scenario: Stack overflow handling failed.");
puts ("On the next stack overflow we will crash!!!");

Should these two statements merged into a single one? I would recommend
to merge them if the two sentences are related to each other, because
then it makes it easier for the translator to understand and translate
both. On the other hand, if one of the two messages is a stereotypic
one, occurring in other places as well, you will do a favour to the
translator by not merging the two. (Identical messages occurring in
several places are combined by xgettext, so the translator has to
handle them once only.)

Translatable strings should be limited to one paragraph; don't let a
single message be longer than ten lines. The reason is that when the
translatable string changes, the translator is faced with the task of
updating the entire translated string. Maybe only a single word will
have changed in the English string, but the translator doesn't see that
(with the current translation tools), therefore she has to proofread
the entire message.

Many GNU programs have a `--help' output that extends over several
screen pages. It is a courtesy towards the translators to split such a
message into several ones of five to ten lines each. While doing that,
you can also attempt to split the documented options into groups, such
as the input options, the output options, and the informative output
options. This will help every user to find the option he is looking
for.

Hardcoded string concatenation is sometimes used to construct English
strings:

strcpy (s, "Replace ");
strcat (s, object1);
strcat (s, " with ");
strcat (s, object2);
strcat (s, "?");

In order to present to the translator only entire sentences, and also
because in some languages the translator might want to swap the order
of `object1' and `object2', it is necessary to change this to use a
format string:

sprintf (s, "Replace %s with %s?", object1, object2);

A similar case is compile time concatenation of strings. The ISO C
99 include file `<inttypes.h>' contains a macro `PRId64' that can be
used as a formatting directive for outputting an `int64_t' integer
through `printf'. It expands to a constant string, usually "d" or "ld"
or "lld" or something like this, depending on the platform. Assume you
have code like

printf ("The amount is %0" PRId64 "\n", number);

The `gettext' tools and library have special support for these
`<inttypes.h>' macros. You can therefore simply write

printf (gettext ("The amount is %0" PRId64 "\n"), number);

The PO file will contain the string "The amount is %0<PRId64>\n". The
translators will provide a translation containing "%0<PRId64>" as well,
and at runtime the `gettext' function's result will contain the
appropriate constant string, "d" or "ld" or "lld".

This works only for the predefined `<inttypes.h>' macros. If you
have defined your own similar macros, let's say `MYPRId64', that are
not known to `xgettext', the solution for this problem is to change the
code like this:

char buf1[100];
sprintf (buf1, "%0" MYPRId64, number);
printf (gettext ("The amount is %s\n"), buf1);

This means, you put the platform dependent code in one statement,
and the internationalization code in a different statement. Note that
a buffer length of 100 is safe, because all available hardware integer
types are limited to 128 bits, and to print a 128 bit integer one needs
at most 54 characters, regardless whether in decimal, octal or
hexadecimal.

All this applies to other programming languages as well. For
example, in Java and C#, string contenation is very frequently used,
because it is a compiler built-in operator. Like in C, in Java, you
would change

System.out.println("Replace "+object1+" with "+object2+"?");

into a statement involving a format string:

System.out.println(
MessageFormat.format("Replace {0} with {1}?",
new Object[] { object1, object2 }));

Similarly, in C#, you would change

Console.WriteLine("Replace "+object1+" with "+object2+"?");

into a statement involving a format string:

Console.WriteLine(
String.Format("Replace {0} with {1}?", object1, object2));

File: gettext.info, Node: Mark Keywords, Next: Marking, Prev: Preparing Strings, Up: Sources

3.3 How Marks Appear in Sources
===============================

All strings requiring translation should be marked in the C sources.
Marking is done in such a way that each translatable string appears to
be the sole argument of some function or preprocessor macro. There are
only a few such possible functions or macros meant for translation, and
their names are said to be marking keywords. The marking is attached
to strings themselves, rather than to what we do with them. This
approach has more uses. A blatant example is an error message produced
by formatting. The format string needs translation, as well as some
strings inserted through some `%s' specification in the format, while
the result from `sprintf' may have so many different instances that it
is impractical to list them all in some `error_string_out()' routine,
say.

This marking operation has two goals. The first goal of marking is
for triggering the retrieval of the translation, at run time. The
keyword are possibly resolved into a routine able to dynamically return
the proper translation, as far as possible or wanted, for the argument
string. Most localizable strings are found in executable positions,
that is, attached to variables or given as parameters to functions.
But this is not universal usage, and some translatable strings appear
in structured initializations. *Note Special cases::.

The second goal of the marking operation is to help `xgettext' at
properly extracting all translatable strings when it scans a set of
program sources and produces PO file templates.

The canonical keyword for marking translatable strings is `gettext',
it gave its name to the whole GNU `gettext' package. For packages
making only light use of the `gettext' keyword, macro or function, it
is easily used _as is_. However, for packages using the `gettext'
interface more heavily, it is usually more convenient to give the main
keyword a shorter, less obtrusive name. Indeed, the keyword might
appear on a lot of strings all over the package, and programmers
usually do not want nor need their program sources to remind them
forcefully, all the time, that they are internationalized. Further, a
long keyword has the disadvantage of using more horizontal space,
forcing more indentation work on sources for those trying to keep them
within 79 or 80 columns.

Many packages use `_' (a simple underline) as a keyword, and write
`_("Translatable string")' instead of `gettext ("Translatable
string")'. Further, the coding rule, from GNU standards, wanting that
there is a space between the keyword and the opening parenthesis is
relaxed, in practice, for this particular usage. So, the textual
overhead per translatable string is reduced to only three characters:
the underline and the two parentheses. However, even if GNU `gettext'
uses this convention internally, it does not offer it officially. The
real, genuine keyword is truly `gettext' indeed. It is fairly easy for
those wanting to use `_' instead of `gettext' to declare:

#include <libintl.h>
#define _(String) gettext (String)

instead of merely using `#include <libintl.h>'.

Later on, the maintenance is relatively easy. If, as a programmer,
you add or modify a string, you will have to ask yourself if the new or
altered string requires translation, and include it within `_()' if you
think it should be translated. `"%s: %d"' is an example of string
_not_ requiring translation!

File: gettext.info, Node: Marking, Next: c-format Flag, Prev: Mark Keywords, Up: Sources

3.4 Marking Translatable Strings
================================

In PO mode, one set of features is meant more for the programmer than
for the translator, and allows him to interactively mark which strings,
in a set of program sources, are translatable, and which are not. Even
if it is a fairly easy job for a programmer to find and mark such
strings by other means, using any editor of his choice, PO mode makes
this work more comfortable. Further, this gives translators who feel a
little like programmers, or programmers who feel a little like
translators, a tool letting them work at marking translatable strings
in the program sources, while simultaneously producing a set of
translation in some language, for the package being internationalized.

The set of program sources, targetted by the PO mode commands
describe here, should have an Emacs tags table constructed for your
project, prior to using these PO file commands. This is easy to do.
In any shell window, change the directory to the root of your project,
then execute a command resembling:

etags src/*.[hc] lib/*.[hc]

presuming here you want to process all `.h' and `.c' files from the
`src/' and `lib/' directories. This command will explore all said
files and create a `TAGS' file in your root directory, somewhat
summarizing the contents using a special file format Emacs can
understand.

For packages following the GNU coding standards, there is a make
goal `tags' or `TAGS' which constructs the tag files in all directories
and for all files containing source code.

Once your `TAGS' file is ready, the following commands assist the
programmer at marking translatable strings in his set of sources. But
these commands are necessarily driven from within a PO file window, and
it is likely that you do not even have such a PO file yet. This is not
a problem at all, as you may safely open a new, empty PO file, mainly
for using these commands. This empty PO file will slowly fill in while
you mark strings as translatable in your program sources.

`,'
Search through program sources for a string which looks like a
candidate for translation (`po-tags-search').

`M-,'
Mark the last string found with `_()' (`po-mark-translatable').

`M-.'
Mark the last string found with a keyword taken from a set of
possible keywords. This command with a prefix allows some
management of these keywords (`po-select-mark-and-mark').

The `,' (`po-tags-search') command searches for the next occurrence
of a string which looks like a possible candidate for translation, and
displays the program source in another Emacs window, positioned in such
a way that the string is near the top of this other window. If the
string is too big to fit whole in this window, it is positioned so only
its end is shown. In any case, the cursor is left in the PO file
window. If the shown string would be better presented differently in
different native languages, you may mark it using `M-,' or `M-.'.
Otherwise, you might rather ignore it and skip to the next string by
merely repeating the `,' command.

A string is a good candidate for translation if it contains a
sequence of three or more letters. A string containing at most two
letters in a row will be considered as a candidate if it has more
letters than non-letters. The command disregards strings containing no
letters, or isolated letters only. It also disregards strings within
comments, or strings already marked with some keyword PO mode knows
(see below).

If you have never told Emacs about some `TAGS' file to use, the
command will request that you specify one from the minibuffer, the
first time you use the command. You may later change your `TAGS' file
by using the regular Emacs command `M-x visit-tags-table', which will
ask you to name the precise `TAGS' file you want to use. *Note Tag
Tables: (emacs)Tags.

Each time you use the `,' command, the search resumes from where it
was left by the previous search, and goes through all program sources,
obeying the `TAGS' file, until all sources have been processed.
However, by giving a prefix argument to the command (`C-u ,'), you may
request that the search be restarted all over again from the first
program source; but in this case, strings that you recently marked as
translatable will be automatically skipped.

Using this `,' command does not prevent using of other regular Emacs
tags commands. For example, regular `tags-search' or
`tags-query-replace' commands may be used without disrupting the
independent `,' search sequence. However, as implemented, the
_initial_ `,' command (or the `,' command is used with a prefix) might
also reinitialize the regular Emacs tags searching to the first tags
file, this reinitialization might be considered spurious.

The `M-,' (`po-mark-translatable') command will mark the recently
found string with the `_' keyword. The `M-.'
(`po-select-mark-and-mark') command will request that you type one
keyword from the minibuffer and use that keyword for marking the
string. Both commands will automatically create a new PO file
untranslated entry for the string being marked, and make it the current
entry (making it easy for you to immediately proceed to its
translation, if you feel like doing it right away). It is possible
that the modifications made to the program source by `M-,' or `M-.'
render some source line longer than 80 columns, forcing you to break
and re-indent this line differently. You may use the `O' command from
PO mode, or any other window changing command from Emacs, to break out
into the program source window, and do any needed adjustments. You
will have to use some regular Emacs command to return the cursor to the
PO file window, if you want command `,' for the next string, say.

The `M-.' command has a few built-in speedups, so you do not have to
explicitly type all keywords all the time. The first such speedup is
that you are presented with a _preferred_ keyword, which you may accept
by merely typing `<RET>' at the prompt. The second speedup is that you
may type any non-ambiguous prefix of the keyword you really mean, and
the command will complete it automatically for you. This also means
that PO mode has to _know_ all your possible keywords, and that it will
not accept mistyped keywords.

If you reply `?' to the keyword request, the command gives a list of
all known keywords, from which you may choose. When the command is
prefixed by an argument (`C-u M-.'), it inhibits updating any program
source or PO file buffer, and does some simple keyword management
instead. In this case, the command asks for a keyword, written in
full, which becomes a new allowed keyword for later `M-.' commands.
Moreover, this new keyword automatically becomes the _preferred_
keyword for later commands. By typing an already known keyword in
response to `C-u M-.', one merely changes the _preferred_ keyword and
does nothing more.

All keywords known for `M-.' are recognized by the `,' command when
scanning for strings, and strings already marked by any of those known
keywords are automatically skipped. If many PO files are opened
simultaneously, each one has its own independent set of known keywords.
There is no provision in PO mode, currently, for deleting a known
keyword, you have to quit the file (maybe using `q') and reopen it
afresh. When a PO file is newly brought up in an Emacs window, only
`gettext' and `_' are known as keywords, and `gettext' is preferred for
the `M-.' command. In fact, this is not useful to prefer `_', as this
one is already built in the `M-,' command.

File: gettext.info, Node: c-format Flag, Next: Special cases, Prev: Marking, Up: Sources

3.5 Special Comments preceding Keywords
=======================================

In C programs strings are often used within calls of functions from the
`printf' family. The special thing about these format strings is that
they can contain format specifiers introduced with `%'. Assume we have
the code

printf (gettext ("String `%s' has %d characters\n"), s, strlen (s));

A possible German translation for the above string might be:

"%d Zeichen lang ist die Zeichenkette `%s'"

A C programmer, even if he cannot speak German, will recognize that
there is something wrong here. The order of the two format specifiers
is changed but of course the arguments in the `printf' don't have.
This will most probably lead to problems because now the length of the
string is regarded as the address.

To prevent errors at runtime caused by translations the `msgfmt'
tool can check statically whether the arguments in the original and the
translation string match in type and number. If this is not the case
and the `-c' option has been passed to `msgfmt', `msgfmt' will give an
error and refuse to produce a MO file. Thus consequent use of `msgfmt
-c' will catch the error, so that it cannot cause cause problems at
runtime.

If the word order in the above German translation would be correct one
would have to write

"%2$d Zeichen lang ist die Zeichenkette `%1$s'"

The routines in `msgfmt' know about this special notation.

Because not all strings in a program must be format strings it is not
useful for `msgfmt' to test all the strings in the `.po' file. This
might cause problems because the string might contain what looks like a
format specifier, but the string is not used in `printf'.

Therefore the `xgettext' adds a special tag to those messages it
thinks might be a format string. There is no absolute rule for this,
only a heuristic. In the `.po' file the entry is marked using the
`c-format' flag in the `#,' comment line (*note PO Files::).

The careful reader now might say that this again can cause problems.
The heuristic might guess it wrong. This is true and therefore
`xgettext' knows about a special kind of comment which lets the
programmer take over the decision. If in the same line as or the
immediately preceding line to the `gettext' keyword the `xgettext'
program finds a comment containing the words `xgettext:c-format', it
will mark the string in any case with the `c-format' flag. This kind
of comment should be used when `xgettext' does not recognize the string
as a format string but it really is one and it should be tested.
Please note that when the comment is in the same line as the `gettext'
keyword, it must be before the string to be translated.

This situation happens quite often. The `printf' function is often
called with strings which do not contain a format specifier. Of course
one would normally use `fputs' but it does happen. In this case
`xgettext' does not recognize this as a format string but what happens
if the translation introduces a valid format specifier? The `printf'
function will try to access one of the parameters but none exists
because the original code does not pass any parameters.

`xgettext' of course could make a wrong decision the other way
round, i.e. a string marked as a format string actually is not a format
string. In this case the `msgfmt' might give too many warnings and
would prevent translating the `.po' file. The method to prevent this
wrong decision is similar to the one used above, only the comment to
use must contain the string `xgettext:no-c-format'.

If a string is marked with `c-format' and this is not correct the
user can find out who is responsible for the decision. See *Note
xgettext Invocation:: to see how the `--debug' option can be used for
solving this problem.

File: gettext.info, Node: Special cases, Next: Names, Prev: c-format Flag, Up: Sources

3.6 Special Cases of Translatable Strings
=========================================

The attentive reader might now point out that it is not always possible
to mark translatable string with `gettext' or something like this.
Consider the following case:

{
static const char *messages[] = {
"some very meaningful message",
"and another one"
};
const char *string;
...
string
= index > 1 ? "a default message" : messages[index];

fputs (string);
...
}

While it is no problem to mark the string `"a default message"' it
is not possible to mark the string initializers for `messages'. What
is to be done? We have to fulfill two tasks. First we have to mark the
strings so that the `xgettext' program (*note xgettext Invocation::)
can find them, and second we have to translate the string at runtime
before printing them.

The first task can be fulfilled by creating a new keyword, which
names a no-op. For the second we have to mark all access points to a
string from the array. So one solution can look like this:

#define gettext_noop(String) String

{
static const char *messages[] = {
gettext_noop ("some very meaningful message"),
gettext_noop ("and another one")
};
const char *string;
...
string
= index > 1 ? gettext ("a default message") : gettext (messages[index]);

fputs (string);
...
}

Please convince yourself that the string which is written by `fputs'
is translated in any case. How to get `xgettext' know the additional
keyword `gettext_noop' is explained in *Note xgettext Invocation::.

The above is of course not the only solution. You could also come
along with the following one:

#define gettext_noop(String) String

{
static const char *messages[] = {
gettext_noop ("some very meaningful message",
gettext_noop ("and another one")
};
const char *string;
...
string
= index > 1 ? gettext_noop ("a default message") : messages[index];

fputs (gettext (string));
...
}

But this has a drawback. The programmer has to take care that he
uses `gettext_noop' for the string `"a default message"'. A use of
`gettext' could have in rare cases unpredictable results.

One advantage is that you need not make control flow analysis to make
sure the output is really translated in any case. But this analysis is
generally not very difficult. If it should be in any situation you can
use this second method in this situation.

File: gettext.info, Node: Names, Next: Libraries, Prev: Special cases, Up: Sources

3.7 Marking Proper Names for Translation
========================================

Should names of persons, cities, locations etc. be marked for
translation or not? People who only know languages that can be written
with Latin letters (English, Spanish, French, German, etc.) are tempted
to say "no", because names usually do not change when transported
between these languages. However, in general when translating from one
script to another, names are translated too, usually phonetically or by
transliteration. For example, Russian or Greek names are converted to
the Latin alphabet when being translated to English, and English or
French names are converted to the Katakana script when being translated
to Japanese. This is necessary because the speakers of the target
language in general cannot read the script the name is originally
written in.

As a programmer, you should therefore make sure that names are marked
for translation, with a special comment telling the translators that it
is a proper name and how to pronounce it. Like this:

printf (_("Written by %s.\n"),
/* TRANSLATORS: This is a proper name. See the gettext
manual, section Names. Note this is actually a non-ASCII
name: The first name is (with Unicode escapes)
"Fran\u00e7ois" or (with HTML entities) "François".
Pronounciation is like "fraa-swa pee-nar". */
_("Francois Pinard"));

As a translator, you should use some care when translating names,
because it is frustrating if people see their names mutilated or
distorted. If your language uses the Latin script, all you need to do
is to reproduce the name as perfectly as you can within the usual
character set of your language. In this particular case, this means to
provide a translation containing the c-cedilla character. If your
language uses a different script and the people speaking it don't
usually read Latin words, it means transliteration; but you should
still give, in parentheses, the original writing of the name - for the
sake of the people that do read the Latin script. Here is an example,
using Greek as the target script:

#. This is a proper name. See the gettext
#. manual, section Names. Note this is actually a non-ASCII
#. name: The first name is (with Unicode escapes)
#. "Fran\u00e7ois" or (with HTML entities) "François".
#. Pronounciation is like "fraa-swa pee-nar".
msgid "Francois Pinard"
msgstr "\phi\rho\alpha\sigma\omicron\alpha \pi\iota\nu\alpha\rho"
" (Francois Pinard)"

Because translation of names is such a sensitive domain, it is a good
idea to test your translation before submitting it.

The translation project `http://sourceforge.net/projects/translation'
has set up a POT file and translation domain consisting of program
author names, with better facilities for the translator than those
presented here. Namely, there the original name is written directly in
Unicode (rather than with Unicode escapes or HTML entities), and the
pronounciation is denoted using the International Phonetic Alphabet (see
`http://www.wikipedia.org/wiki/International_Phonetic_Alphabet').

However, we don't recommend this approach for all POT files in all
packages, because this would force translators to use PO files in UTF-8
encoding, which is - in the current state of software (as of 2003) - a
major hassle for translators using GNU Emacs or XEmacs with po-mode.

File: gettext.info, Node: Libraries, Prev: Names, Up: Sources

3.8 Preparing Library Sources
=============================

When you are preparing a library, not a program, for the use of
`gettext', only a few details are different. Here we assume that the
library has a translation domain and a POT file of its own. (If it
uses the translation domain and POT file of the main program, then the
previous sections apply without changes.)

1. The library code doesn't call `setlocale (LC_ALL, "")'. It's the
responsibility of the main program to set the locale. The
library's documentation should mention this fact, so that
developers of programs using the library are aware of it.

2. The library code doesn't call `textdomain (PACKAGE)', because it
would interfere with the text domain set by the main program.

3. The initialization code for a program was

setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);

For a library it is reduced to

bindtextdomain (PACKAGE, LOCALEDIR);

If your library's API doesn't already have an initialization
function, you need to create one, containing at least the
`bindtextdomain' invocation. However, you usually don't need to
export and document this initialization function: It is sufficient
that all entry points of the library call the initialization
function if it hasn't been called before. The typical idiom used
to achieve this is a static boolean variable that indicates
whether the initialization function has been called. Like this:

static bool libfoo_initialized;

static void
libfoo_initialize (void)
{
bindtextdomain (PACKAGE, LOCALEDIR);
libfoo_initialized = true;
}

/* This function is part of the exported API. */
struct foo *
create_foo (...)
{
/* Must ensure the initialization is performed. */
if (!libfoo_initialized)
libfoo_initialize ();
...
}

/* This function is part of the exported API. The argument must be
non-NULL and have been created through create_foo(). */
int
foo_refcount (struct foo *argument)
{
/* No need to invoke the initialization function here, because
create_foo() must already have been called before. */
...
}

4. The usual declaration of the `_' macro in each source file was

#include <libintl.h>
#define _(String) gettext (String)

for a program. For a library, which has its own translation
domain, it reads like this:

#include <libintl.h>
#define _(String) dgettext (PACKAGE, String)

In other words, `dgettext' is used instead of `gettext'.
Similary, the `dngettext' function should be used in place of the
`ngettext' function.

File: gettext.info, Node: Template, Next: Creating, Prev: Sources, Up: Top

4 Making the PO Template File
*****************************

After preparing the sources, the programmer creates a PO template file.
This section explains how to use `xgettext' for this purpose.

`xgettext' creates a file named `DOMAINNAME.po'. You should then
rename it to `DOMAINNAME.pot'. (Why doesn't `xgettext' create it under
the name `DOMAINNAME.pot' right away? The answer is: for historical
reasons. When `xgettext' was specified, the distinction between a PO
file and PO file template was fuzzy, and the suffix `.pot' wasn't in
use at that time.)

* Menu:

* xgettext Invocation:: Invoking the `xgettext' Program

File: gettext.info, Node: xgettext Invocation, Prev: Template, Up: Template

4.1 Invoking the `xgettext' Program
===================================

xgettext [OPTION] [INPUTFILE] ...

The `xgettext' program extracts translatable strings from given
input files.

4.1.1 Input file location
-------------------------

`INPUTFILE ...'
Input files.

`-f FILE'
`--files-from=FILE'
Read the names of the input files from FILE instead of getting
them from the command line.

`-D DIRECTORY'
`--directory=DIRECTORY'
Add DIRECTORY to the list of directories. Source files are
searched relative to this list of directories. The resulting `.po'
file will be written relative to the current directory, though.

If INPUTFILE is `-', standard input is read.

4.1.2 Output file location
--------------------------

`-d NAME'
`--default-domain=NAME'
Use `NAME.po' for output (instead of `messages.po').

`-o FILE'
`--output=FILE'
Write output to specified file (instead of `NAME.po' or
`messages.po').

`-p DIR'
`--output-dir=DIR'
Output files will be placed in directory DIR.

If the output FILE is `-' or `/dev/stdout', the output is written to
standard output.

4.1.3 Choice of input file language
-----------------------------------

`-L NAME'
`--language=NAME'
Specifies the language of the input files. The supported languages
are `C', `C++', `ObjectiveC', `PO', `Python', `Lisp', `EmacsLisp',
`librep', `Scheme', `Smalltalk', `Java', `JavaProperties', `C#',
`awk', `YCP', `Tcl', `Perl', `PHP', `GCC-source', `NXStringTable',
`RST', `Glade'.

`-C'
`--c++'
This is a shorthand for `--language=C++'.

By default the language is guessed depending on the input file name
extension.

4.1.4 Input file interpretation
-------------------------------

`--from-code=NAME'
Specifies the encoding of the input files. This option is needed
only if some untranslated message strings or their corresponding
comments contain non-ASCII characters. Note that Python, Tcl, and
Glade input files are always assumed to be in UTF-8, regardless of
this option.

By default the input files are assumed to be in ASCII.

4.1.5 Operation mode
--------------------

`-j'
`--join-existing'
Join messages with existing file.

`-x FILE'
`--exclude-file=FILE'
Entries from FILE are not extracted. FILE should be a PO or POT
file.

`-c [TAG]'
`--add-comments[=TAG]'
Place comment block with TAG (or those preceding keyword lines) in
output file.

4.1.6 Language specific options
-------------------------------

`-a'
`--extract-all'
Extract all strings.

This option has an effect with most languages, namely C, C++,
ObjectiveC, Shell, Python, Lisp, EmacsLisp, librep, Java, C#, awk,
Tcl, Perl, PHP, GCC-source, Glade.

`-k KEYWORDSPEC'
`--keyword[=KEYWORDSPEC]'
Additional keyword to be looked for (without KEYWORDSPEC means not
to use default keywords).

If KEYWORDSPEC is a C identifer ID, `xgettext' looks for strings
in the first argument of each call to the function or macro ID.
If KEYWORDSPEC is of the form `ID:ARGNUM', `xgettext' looks for
strings in the ARGNUMth argument of the call. If KEYWORDSPEC is
of the form `ID:ARGNUM1,ARGNUM2', `xgettext' looks for strings in
the ARGNUM1st argument and in the ARGNUM2nd argument of the call,
and treats them as singular/plural variants for a message with
plural handling.
The default keyword specifications, which are always looked for if
not explicitly disabled, are `gettext', `dgettext:2',
`dcgettext:2', `ngettext:1,2', `dngettext:2,3', `dcngettext:2,3',
and `gettext_noop'.
This option has an effect with most languages, namely C, C++,
ObjectiveC, Shell, Python, Lisp, EmacsLisp, librep, Java, C#, awk,
Tcl, Perl, PHP, GCC-source, Glade.

`--flag=WORD:ARG:FLAG'
Specifies additional flags for strings occurring as part of the
ARGth argument of the function WORD. The possible flags are the
possible format string indicators, such as `c-format', and their
negations, such as `no-c-format', possibly prefixed with `pass-'.
The meaning of `--flag=FUNCTION:ARG:LANG-format' is that in
language LANG, the specified FUNCTION expects as ARGth argument a
format string. (For those of you familiar with GCC function
attributes, `--flag=FUNCTION:ARG:c-format' is roughly equivalent
to the declaration `__attribute__ ((__format__ (__printf__, ARG,
...)))' attached to FUNCTION in a C source file.) For example, if
you use the `error' function from GNU libc, you can specify its
behaviour through `--flag=error:3:c-format'. The effect of this
specification is that `xgettext' will mark as format strings all
`gettext' invocations that occur as ARGth argument of FUNCTION.
This is useful when such strings contain no format string
directives: together with the checks done by `msgfmt -c' it will
ensure that translators cannot accidentally use format string
directives that would lead to a crash at runtime.
The meaning of `--flag=FUNCTION:ARG:pass-LANG-format' is that in
language LANG, if the FUNCTION call occurs in a position that must
yield a format string, then its ARGth argument must yield a format
string of the same type as well. (If you know GCC function
attributes, the `--flag=FUNCTION:ARG:pass-c-format' option is
roughly equivalent to the declaration `__attribute__
((__format_arg__ (ARG)))' attached to FUNCTION in a C source file.)
For example, if you use the `_' shortcut for the `gettext'
function, you should use `--flag=_:1:pass-c-format'. The effect
of this specification is that `xgettext' will propagate a format
string requirement for a `_("string")' call to its first argument,
the literal `"string"', and thus mark it as a format string. This
is useful when such strings contain no format string directives:
together with the checks done by `msgfmt -c' it will ensure that
translators cannot accidentally use format string directives that
would lead to a crash at runtime.
This option has an effect with most languages, namely C, C++,
ObjectiveC, Shell, Python, Lisp, EmacsLisp, librep, Scheme, Java,
C#, awk, YCP, Tcl, Perl, PHP, GCC-source.

`-T'
`--trigraphs'
Understand ANSI C trigraphs for input.
This option has an effect only with the languages C, C++,
ObjectiveC.

`--qt'
Recognize Qt format strings.
This option has an effect only with the language C++.

`--debug'
Use the flags `c-format' and `possible-c-format' to show who was
responsible for marking a message as a format string. The latter
form is used if the `xgettext' program decided, the format form is
used if the programmer prescribed it.

By default only the `c-format' form is used. The translator should
not have to care about these details.

This implementation of `xgettext' is able to process a few awkward
cases, like strings in preprocessor macros, ANSI concatenation of
adjacent strings, and escaped end of lines for continued strings.

4.1.7 Output details
--------------------

`--force-po'
Always write an output file even if no message is defined.

`-i'
`--indent'
Write the .po file using indented style.

`--no-location'
Do not write `#: FILENAME:LINE' lines.

`-n'
`--add-location'
Generate `#: FILENAME:LINE' lines (default).

`--strict'
Write out a strict Uniforum conforming PO file. Note that this
Uniforum format should be avoided because it doesn't support the
GNU extensions.

`--properties-output'
Write out a Java ResourceBundle in Java `.properties' syntax. Note
that this file format doesn't support plural forms and silently
drops obsolete messages.

`--stringtable-output'
Write out a NeXTstep/GNUstep localized resource file in `.strings'
syntax. Note that this file format doesn't support plural forms.

`-w NUMBER'
`--width=NUMBER'
Set the output page width. Long strings in the output files will
be split across multiple lines in order to ensure that each line's
width (= number of screen columns) is less or equal to the given
NUMBER.

`--no-wrap'
Do not break long message lines. Message lines whose width
exceeds the output page width will not be split into several
lines. Only file reference lines which are wider than the output
page width will be split.

`-s'
`--sort-output'
Generate sorted output. Note that using this option makes it much
harder for the translator to understand each message's context.

`-F'
`--sort-by-file'
Sort output by file location.

`--omit-header'
Don't write header with `msgid ""' entry.

This is useful for testing purposes because it eliminates a source
of variance for generated `.gmo' files. With `--omit-header', two
invocations of `xgettext' on the same files with the same options
at different times are guaranteed to produce the same results.

`--copyright-holder=STRING'
Set the copyright holder in the output. STRING should be the
copyright holder of the surrounding package. (Note that the msgstr
strings, extracted from the package's sources, belong to the
copyright holder of the package.) Translators are expected to
transfer or disclaim the copyright for their translations, so that
package maintainers can distribute them without legal risk. If
STRING is empty, the output files are marked as being in the
public domain; in this case, the translators are expected to
disclaim their copyright, again so that package maintainers can
distribute them without legal risk.

The default value for STRING is the Free Software Foundation, Inc.,
simply because `xgettext' was first used in the GNU project.

`--foreign-user'
Omit FSF copyright in output. This option is equivalent to
`--copyright-holder='''. It can be useful for packages outside
the GNU project that want their translations to be in the public
domain.

`--msgid-bugs-address=EMAIL@ADDRESS'
Set the reporting address for msgid bugs. This is the email
address or URL to which the translators shall report bugs in the
untranslated strings:

- Strings which are not entire sentences, see the maintainer
guidelines in *Note Preparing Strings::.

- Strings which use unclear terms or require additional context
to be understood.

- Strings which make invalid assumptions about notation of
date, time or money.

- Pluralisation problems.

- Incorrect English spelling.

- Incorrect formatting.

It can be your email address, or a mailing list address where
translators can write to without being subscribed, or the URL of a
web page through which the translators can contact you.

The default value is empty, which means that translators will be
clueless! Don't forget to specify this option.

`-m [STRING]'
`--msgstr-prefix[=STRING]'
Use STRING (or "" if not specified) as prefix for msgstr entries.

`-M [STRING]'
`--msgstr-suffix[=STRING]'
Use STRING (or "" if not specified) as suffix for msgstr entries.

4.1.8 Informative output
------------------------

`-h'
`--help'
Display this help and exit.

`-V'
`--version'
Output version information and exit.

File: gettext.info, Node: Creating, Next: Updating, Prev: Template, Up: Top

5 Creating a New PO File
************************

When starting a new translation, the translator creates a file called
`LANG.po', as a copy of the `PACKAGE.pot' template file with
modifications in the initial comments (at the beginning of the file)
and in the header entry (the first entry, near the beginning of the
file).

The easiest way to do so is by use of the `msginit' program. For
example:

$ cd PACKAGE-VERSION
$ cd po
$ msginit

The alternative way is to do the copy and modifications by hand. To
do so, the translator copies `PACKAGE.pot' to `LANG.po'. Then she
modifies the initial comments and the header entry of this file.

* Menu:

* msginit Invocation:: Invoking the `msginit' Program
* Header Entry:: Filling in the Header Entry

File: gettext.info, Node: msginit Invocation, Next: Header Entry, Prev: Creating, Up: Creating

5.1 Invoking the `msginit' Program
==================================

msginit [OPTION]

The `msginit' program creates a new PO file, initializing the meta
information with values from the user's environment.

5.1.1 Input file location
-------------------------

`-i INPUTFILE'
`--input=INPUTFILE'
Input POT file.

If no INPUTFILE is given, the current directory is searched for the
POT file. If it is `-', standard input is read.

5.1.2 Output file location
--------------------------

`-o FILE'
`--output-file=FILE'
Write output to specified PO file.

If no output file is given, it depends on the `--locale' option or
the user's locale setting. If it is `-', the results are written to
standard output.

5.1.3 Input file syntax
-----------------------

`-P'
`--properties-input'
Assume the input file is a Java ResourceBundle in Java
`.properties' syntax, not in PO file syntax.

`--stringtable-input'
Assume the input file is a NeXTstep/GNUstep localized resource
file in `.strings' syntax, not in PO file syntax.

5.1.4 Output details
--------------------

`-l LL_CC'
`--locale=LL_CC'
Set target locale. LL should be a language code, and CC should be
a country code. The command `locale -a' can be used to output a
list of all installed locales. The default is the user's locale
setting.

`--no-translator'
Declares that the PO file will not have a human translator and is
instead automatically generated.

`-p'
`--properties-output'
Write out a Java ResourceBundle in Java `.properties' syntax. Note
that this file format doesn't support plural forms and silently
drops obsolete messages.

`--stringtable-output'
Write out a NeXTstep/GNUstep localized resource file in `.strings'
syntax. Note that this file format doesn't support plural forms.

5.1.5 Informative output
------------------------

`-h'
`--help'
Display this help and exit.

`-V'
`--version'
Output version information and exit.

File: gettext.info, Node: Header Entry, Prev: msginit Invocation, Up: Creating

5.2 Filling in the Header Entry
===============================

The initial comments "SOME DESCRIPTIVE TITLE", "YEAR" and "FIRST AUTHOR
<EMAIL@ADDRESS>, YEAR" ought to be replaced by sensible information.
This can be done in any text editor; if Emacs is used and it switched
to PO mode automatically (because it has recognized the file's suffix),
you can disable it by typing `M-x fundamental-mode'.

Modifying the header entry can already be done using PO mode: in
Emacs, type `M-x po-mode RET' and then `RET' again to start editing the
entry. You should fill in the following fields.

Project-Id-Version
This is the name and version of the package.

Report-Msgid-Bugs-To
This has already been filled in by `xgettext'. It contains an
email address or URL where you can report bugs in the untranslated
strings:

- Strings which are not entire sentences, see the maintainer
guidelines in *Note Preparing Strings::.

- Strings which use unclear terms or require additional context
to be understood.

- Strings which make invalid assumptions about notation of
date, time or money.

- Pluralisation problems.

- Incorrect English spelling.

- Incorrect formatting.

POT-Creation-Date
This has already been filled in by `xgettext'.

PO-Revision-Date
You don't need to fill this in. It will be filled by the Emacs PO
mode when you save the file.

Last-Translator
Fill in your name and email address (without double quotes).

Language-Team
Fill in the English name of the language, and the email address or
homepage URL of the language team you are part of.

Before starting a translation, it is a good idea to get in touch
with your translation team, not only to make sure you don't do
duplicated work, but also to coordinate difficult linguistic
issues.

In the Free Translation Project, each translation team has its own
mailing list. The up-to-date list of teams can be found at the
Free Translation Project's homepage,
`http://www.iro.umontreal.ca/contrib/po/HTML/', in the "National
teams" area.

Content-Type
Replace `CHARSET' with the character encoding used for your
language, in your locale, or UTF-8. This field is needed for
correct operation of the `msgmerge' and `msgfmt' programs, as well
as for use