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From: ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe)
Newsgroups: comp.lang.c,alt.sources.d
Subject: Re: Small introspective program
Message-ID: <4967@goanna.cs.rmit.oz.au>
Date: 14 Mar 91 04:33:25 GMT
References: <1991Mar10.231230.1301@casbah.acns.nwu.edu> <DQ.90AA@xds13.ferranti.com>
Followup-To: comp.lang.c
Organization: Comp Sci, RMIT, Melbourne, Australia
Lines: 36

[About the hack for including a command to compile itself in a C program.]

Many years ago Tom Duff wrote a nifty little program called "com";
David Tilbrook added some options, and I later added another.

	com [-c$Escape] [-n] [-o | -x] file...

The program searches each file in turn for a comment
	/*% <command> \n
where % is the Escape chacter (which defaults to "%").  Any Escape
character occurring in the file is replaced by the file name from the
command line.  Then
    - if the -o flag appeared, the command is written to stdout, or
    - if the -x flag appeared, the command is written to stderr
    - if the -n flag did NOT appear, the command is given to system().
So the "com" program itself starts with a comment
	/*% cc -o com -O %
	*/
In an AWK script, one could have
	#/*% awk -f %

When 'make' come around I gradually stopped using 'com'.

> ! #ifdef notdef /*
> >   cc $0 -g -o `basename $0 .c` -Ineeded-includes -lneeded-libraries 
> !   exit
> +   */
> > #endif notdef

If you want to use the "shell-in-C" trick, though, it can be simplified:
#if 0 /*
exec cc -g -o `basename $0 .c` -Ineeded-includes $0 -lneeded-libraries 
*/
#endif
-- 
The purpose of advertising is to destroy the freedom of the market.