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From: ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe)
Newsgroups: comp.lang.c,comp.software-eng
Subject: Re: Source File Organization
Message-ID: <4836@goanna.cs.rmit.oz.au>
Date: 27 Feb 91 07:49:29 GMT
References: <1991Feb26.045242.23453@rfengr.com>
Followup-To: comp.lang.c
Organization: Comp Sci, RMIT, Melbourne, Australia
Lines: 47

In article <1991Feb26.045242.23453@rfengr.com>, rfarris@rfengr.com (Rick Farris) writes:
> I have a problem that I'm sure has been solved in the C
> language before; would someone point me in the right
> direction?

> typedef enum { A, B, C, D } CMD;
> char ltrs[] = { 'A', 'B', 'C', 'D' };

> My problem is: How do I keep the darn things in sync?

I've seen this one often enough that I think it belongs in the FAQ list.
The answer is that you *don't* do it by any special magic in the C source
code itself, but use some other tool to transform a "mini language" to
both files.  For example, write a little file like
	cmd.defs
	-----------
	A	"Alfa"
	B	"Bravo"
	...
	D	"Delta"
and two awk scripts:
	cmd.awk
	-------------
	BEGIN	{ print "typedef enum {" }
		{ print $1, "," }
	END	{ print "} CMD;" }
and
	ltrs.awk
	-------------
	BEGIN	{ print "char ltrs[] = {" }
		{ print "  '" substr($2,1,1) "'," }
	END	{ print "};"}
and then put in your Makefile
	cmd.h: cmd.defs cmd.awk
		awk -f cmd.awk <cmd.defs >cmd.h
	ltrs.c: cmd.defs ltrs.awk
		awk -f ltrs.awk <cmd.defs >ltrs.c

(This is not a UNIX-specific solution: make and awk lookalikes are
available for other systems.  If you haven't got them, it's trivial
to do this in C itself.)

Moral: C source code is plain text that can be generated by other
programs.

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