Path: utzoo!utgpu!attcan!uunet!husc6!ogccse!blake!uw-beaver!fluke!ssc-vax!dmg
From: dmg@ssc-vax.UUCP (David Geary)
Newsgroups: comp.lang.c
Subject: Re: Subroutine layout in C
Keywords: Here's a couple of handy macros...
Message-ID: <2459@ssc-vax.UUCP>
Date: 5 Jan 89 17:44:15 GMT
Organization: Boeing Aerospace Corp., Seattle WA
Lines: 57


Frank Reiter writes:
>In article <2800002@uxg.cso.uiuc.edu> phil@uxg.cso.uiuc.edu writes:
>>
>> I want S to be known outside.
>>I also want to have two subroutines X and Y to be known ONLY to S (not known
>>outside of S).  Either can be called by S, and each calls the other in a
>>recursive way.  I also need to share several variables entirely within
>>this context (shared between S, X, Y).  They can be static.

>Put S(), X(), and Y() in their own file.  Declare X() and Y() to be static
>and do the same with any global variables to be accessed only by S(), X(),
>and Y().

>Other modules will be able to call S() but not X() or Y() or any of the static
>variables.

  Frank is correct, this is exactly what you want to do.  However, I like
to do the following:

#define PRIVATE static
#define PUBLIC 

Now, we can declare the functions S(), X(), and Y() thusly:

PUBLIC int S()
{
 ...
}

PRIVATE int X()
{
 ...
}

PRIVATE int Y()
{
 ...
}

And, of course, we can declare external variables in the same manner:

PUBLIC  int   x,y;
PRIVATE float f,g;

BTW, these macros are not my invention, I first saw them in a book entitled
"Operating Systems Design and Implementation" (I think the title is correct).
A very good book BTW, on the MINIX OS.

David


-- 
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~ David Geary, Boeing Aerospace,               ~ 
~ #define    Seattle     RAIN                  ~
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