Newsgroups: comp.lang.c
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From: scs@adam.mit.edu (Steve Summit)
Subject: Re: Prototypes local or global opinions wanted
Message-ID: <1991Jun26.153026.7456@athena.mit.edu>
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Reply-To: scs@adam.mit.edu
Organization: Thermal Technologies, Cambridge, MA
References: <phil.7968@phd.UUCP>
Date: Wed, 26 Jun 91 15:30:26 GMT
Lines: 41

In article <phil.7968@phd.UUCP> phil@phd.UUCP (H Phil Duby) writes:
>In article <1991Jun21.004933.4197@athena.mit.edu> scs@adam.mit.edu (Steve Summit) writes:
>> Most certainly.  If prototypes are used, they MUST be placed in
>> header files...
>
>If the function you want to prototype (VERY good idea IMHO) is used by a
>set of other functions that can be convienently grouped together into a
>single source file, seperate from other functions that should not call the
>function, declare the prototype global in that source file, but with the
>static qualifier.

Phil is quite correct.  I forgot this exception when I made my
blanket statement; a static prototype does belong in the same
source file where the function is defined and used.

>For purists who insist prototypes should also be declared in a header file...
>use the (also talked/beaten to death) option of
>putting #ifdef #endif pairs around the prototype (with or without the
>static qualifier), and provide the appropriate define only in the source
>file(s) that SHOULD be calling the function.

I hope Phil didn't get the impression I was that kind of a purist --
blindly putting static prototypes in header files just because of
some silly rule would be, well, silly.

Using private #ifdefs in public header files is mildly ugly, and
should only be resorted to when the private declarations must be
shared by a group of "private" files which for some reason cannot
be combined into one file, such that the static storage-class
cannot be used.

(Note, by the way, that a header-file declaration for a static
object or function, if such a declaration is used at all, should
also have the static storage-class, because the ANSI standard
says that the first declaration seen must agree with the
definition with respect to the presence or absence of the static
storage-class.  This is another old and tired topic, which I am
not suggesting that we reopen.)

                                            Steve Summit
                                            scs@adam.mit.edu