Track the filename/line number of an anonymous coderef

Use the imported "Sub" instead of "sub", and you can create an anonymous coderef that acts normally except when dereferenced as a string, where it returns the filename and line number of where it was defined. See the example for usage.

This code came from the discussion in the thread that includes •Re^5: How to de-reference a coderef?.

BEGIN {
  package MagicalCoderef;

  use overload '""' => sub {
    require B;

    my $ref = shift;
    my $gv = B::svref_2object($ref)->GV;
    sprintf "%s:%d", $gv->FILE, $gv->LINE;
  };

  sub main::Sub (&) {
    return bless shift, __PACKAGE__;
  }
}

my $s = Sub { print +shift };
$s->("hello world\n");
print "$s\n";
[download]

Comment on Track the filename/line number of an anonymous coderef Download Code

Replies are listed 'Best First'.
Re: Track the filename/line number of an anonymous coderef by brian_d_foy (Abbot) on Dec 11, 2004 at 06:23 UTC
I changed this around to do it for arbitrary coderefs, since I get to deal with some that come from other sources. Instead of catching them at definition time, I "enchant" them later. This looks like it could be a useful decorator if I work on the concept a little more. So Randal, who wants to upload it to CPAN first? `#!/usr/bin/perl my $a = sub { print "I am A\n" }; my $b = sub { print "I am B\n" }; $a->(); $b->(); $c = MagicalCodeRef->enchant( $a ); $a->(); print STDERR "That was $a I just called\n"; BEGIN { package MagicalCodeRef; use overload '""' => sub { require B; my $ref = shift; my $gv = B::svref_2object($ref)->GV; sprintf "%s:%d", $gv->FILE, $gv->LINE; }; sub enchant { bless $_[1], $_[0] } }` [download] -- brian d foy <bdfoy@cpan.org>	[reply] [d/l]
Re^2: Track the filename/line number of an anonymous coderef by Anonymous Monk on May 12, 2022 at 14:20 UTC
A warning to anybody who finds this from google. This approach worked perfectly in perl 5.8.8 and perl 5.20.2, but as of perl 5.30.3, this no longer works. At that version, "`$gv->LINE`" outputs some huge number instead of a LINE number. Somehow using "`x $sub`" in the debugger still gets the correct answer, so I think there must be some solution.	[reply] [d/l] [select]
Re^3: Track the filename/line number of an anonymous coderef by hv (Prior) on May 12, 2022 at 17:56 UTC
This approach worked perfectly in perl 5.8.8 and perl 5.20.2, but as of perl 5.30.3, this no longer works. At that version, "$gv->LINE" outputs some huge number instead of a LINE number. I can't reproduce the problem you report: it works fine for me at 5.30.0, 5.32.0 and 5.34.0 (which I happen to have installed), and I just built 5.30.3 and it works fine for me on that too. Could you provide `perl -V` output? Perhaps there's something specific to your build.	[reply] [d/l]


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