Find Perl Package and Subroutine Location

When we use other people’s Perl programs or packages, we want to see the source code of Perl subroutine.

Here is Steve’s practice to find the root of a package and a subroutine. The content is from online and is tested in my local environment.

Find Package

Save the following content into a file fine_pm, and make it executable.

Then use find_pm <module name> to find the module.

#!/usr/bin/env perl

use strict;
use warnings;

my $sub_path = shift @ARGV;

if (not defined $sub_path)
{
  print "\nERROR: No arguments supplied.\n\n";
  print "Syntax: find_pm [Perl Module]\n\n";

  exit 1;
}

my $sub_path_orig = $sub_path;
$sub_path =~ s/::/\//g;

foreach my $lib_path (@INC)
{
  my $full_path = "$lib_path/$sub_path";
  if ($full_path !~ /\.pm$/)
  {
    $full_path .= ".pm";
  }
#   print "DEBUG: $full_path\n";
  if (-e $full_path)
  {
    print "$full_path\n";
    exit 0;
  }
}

print "$sub_path_orig: module not found\n";

Find Subroutine

The following script can help to find the subroutine and print out the subroutine’s source file location and number of line.

use mypl ;

sub find_sub (\&) {
    my $code = shift;
    require B;
    my $obj = B::svref_2object($code);  # create a B::CV object from $code

    print "$code:\n";

    print "  $$_[0]: $$_[1]\n" for
        [file    => $obj->FILE],
        [line    => $obj->GV->LINE],
        [name    => $obj->GV->NAME],
        [package => $obj->STASH->NAME];
}

find_sub &::mypl::dev_test ;