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From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: subroutine inspecting its calling environment
Message-ID: <100405@convex.convex.com>
Date: 6 Mar 90 16:31:07 GMT
References: <JBW.90Mar5185907@bucsf.bu.edu> <7283@jpl-devvax.JPL.NASA.GOV>
Sender: news@convex.com
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 39

In article <7283@jpl-devvax.JPL.NASA.GOV> lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) writes:
>In article <JBW.90Mar5185907@bucsf.bu.edu> jbw@bucsf.bu.edu (Joe Wells) writes:
>: Some questions for the great perl gods:
>: 
>: 1.  Can a subroutine tell whether it was invoked without arguments?
>: 
>:     example:  &subroutine_name;
>
>Not that I know of.

Really?  $#_ has always worked for me:


    #!/usr/bin/perl

    &callme;
    &callme('blue');
    &callme(0);
    &callme(7,1);
    &callme();

    exit 0;

    sub callme {
	local($count) = $#_ + 1;  # assumes $[ == 0
	printf "i was called with %s argument%s\n", 
		    $count, ($count == 1) ? '' : 's';
    } 


Is there some reason this is not reliable?


--tom
--

    Tom Christiansen                       {uunet,uiucdcs,sun}!convex!tchrist 
    Convex Computer Corporation                            tchrist@convex.COM
		 "EMACS belongs in <sys/errno.h>: Editor too big!"