libsm : C Language Portability Macros



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     libsm : C Language Portability Macros 
    
 $Id: cdefs.html,v 1.2 2000/12/07 17:33:09 dmoen Exp $


 Description 

The header file <sm/cdefs.h>
defines portable interfaces to non-portable features
of various C compilers.
It also assists you in writing C header files that are compatible
with C++.



 __P(parameterlist) 

    This macro is used to write portable function prototypes.
    For example,

int foo __P((int));



 __CONCAT(x,y) 

    This macro concatenates two tokens x and y,
    forming a single token xy.
    Warning: make sure there is no white space around the arguments x and y.
    


 __STRING(x) 

    This macro converts the token sequence x into a string literal.
    


 __BEGIN_DECLS, __END_DECLS 

    These macros are used to write C header files that are compatible
    with C++ compilers.
    Put __BEGIN_DECLS before the first function or variable
    declaration in your header file,
    and put __END_DECLS after the last function or variable
    declaration.
    


 const, signed, volatile 

    For pre-ANSI C compilers, const, signed
    and volatile are defined as empty macros.
    This means you can use these keywords without introducing
    portability problems.
    


 SM_DEAD(function_declaration) 

    This macro modifies a prototype of a function
    that does not return to its caller.
    With some versions of gcc, this will result in slightly better code,
    and can suppress some useless warnings produced by gcc -Wall.
    For example,

SM_DEAD(void exit __P((int)));



 SM_UNUSED(variable_declaration) 

    This macro modifies a definition of an unused
    local variable, global variable or function parameter
    in order to suppress compiler warnings.
    Examples:

SM_UNUSED(static const char Id[]) = "@(#)$Id: cdefs.html,v 1.2 2000/12/07 17:33:09 dmoen Exp $";
void
foo(x)
	SM_UNUSED(int x);
{
	SM_UNUSED(int y) = 0;
	return 0;
}
void
bar(SM_UNUSED(int x))
{
	return 0;
}