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From: ramin@scampi.UUCP
Newsgroups: comp.lang.c
Subject: Re: Can a subfunction find the name of the calling function?
Message-ID: <185@scampi.UUCP>
Date: Tue, 5-May-87 19:35:12 EDT
Article-I.D.: scampi.185
Posted: Tue May  5 19:35:12 1987
Date-Received: Fri, 8-May-87 01:58:29 EDT
References: <12620001@acf4.UUCP>
Organization: Systems Control, Palo Alto, CA
Lines: 83
Summary: Here's one way...

In article <12620001@acf4.UUCP>, woo@acf4.UUCP (Alex C. Woo) writes:
> 
> Is there anything comparable to getarg and iargc for subroutines
> or functions?  How can a function determine the name of the function
> which calls it or the number of calling arguments, either in C
> or f77?
> 
> Alex Woo

Here's one way of getting the function name. It might not appeal to some
people's aesthetic, but it works... (I recall seeing something like it
in GNU emacs in the form of DEFUN but it's been a while (:-) 
(more commentary at the end...)

***************************************************************************

#define	CALL1(func,a) 			func("func",a)
#define	CALL2(func,a,b)			func("func",a,b)
#define	CALL3(func,a,b,c)		func("func",a,b,c)
#define	SUB1(func,a)			func(name,a) char *name;

main()
{
  CALL3(first,1,2,3);
  CALL1(foo,"this is a parameter");
}

first(name,x,y,z)
char	*name;
int	x,y,z;
{
  printf("%s - %d - %d - %d\n",name,x,y,z);
}

SUB1(foo,text)
char	*text;
{
  printf("%s -- %s\n",name,text);
}
***************************************************************************

It was used in one project to print out debugging and manual traceback
information out... It was actually used within the following context...

#ifndef TRACEBACK
#define	CALL1(func,a)	func(a)
#else
#define	CALL1(func,a)	log_name(func);	func("func",a)
#endif

Where log_name would be a function that would write something like
"Entering function: foo at [time/date]" to a temporary log-file.

Taking out TRACEBACK would just force cpp to generate normal code
without all the strings and function calls... In fact, the source to
the log_name function would not even be #include'd if TRACEBACK was
undefined... It's a fairly painless insurance policy for way down the line...

Nobody complained after the first time they checked out the
log-file to see where their programs had gone to pieces. Especially
when you get one of those intermittent bugs that happen after
8 hours of crunching in real-time... (especially if it doesn't happen
in BSD (Ultrix) but does in VMS... Yow!)
Most people, in fact, customized the macro's to print out further 
logging info... some got carried away... But that's another story (;-)

This stuff was tested on Ultrix, Sun, and VAX/VMS... Your mileage may
vary... caveat emptor...

'nuff said...

r...
 

-- 

(insert-file ".disclaimers")

ramin firoozye'			{ihnp4,lll-lcc,hoptoad}!scampi!ramin
systems control inc.		(415) 494-1165 x-1777
1801 page mill road
palo alto, ca  94304
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