There is another method to get the name other than pad walking or name passing. I used this method in the 11 year old CGI::Ex::Dump module (looks like the POD for that module is rather lackluster - guess I should update it after 11 years). We've used a variant of this for some time.

Whenever we debug we also like to see the line location - once we have parsed for the line location it is trivial to open the code and look for that line and do a very barebones parse. Apologist notes: This may not be academically correct, but we don't care - we're debugging. The output will also not be right if the source file changes, or the debug line is too complex - but again I don't care about a perfect solution - I want a fast good enough solution. Maybe someday we'll update it to a padwalker, but it is really rather trivial as it is. Here is a sample:

$ cat sample.pl 
use strict;
use CGI::Ex::Dump qw(debug);
my $a = 123;
my @b = qw(1..10);
my $obj = bless {}, __PACKAGE__;
debug;
debug $a, \@b, $obj;
debug "Arbitrary String "x2;
debug {"a".."f"};

$ perl sample.pl 
debug: sample.pl line 6
debug: sample.pl line 7
  $a = 123;
  \@b = [
            "1..10"
          ];
  $obj = bless( {}, 'main' );
debug: sample.pl line 8
  String = "Arbitrary String Arbitrary String ";
debug: sample.pl line 9
  {"a".."f"} = {
            a => "b",
            c => "d",
            e => "f"
          };
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The actual dumping is done by Data::Dumper, so setting all Data::Dumper options will control the output. It should be easy enough to replace the output with Data::Dump, or Data::Dumper::Simple, or even JSON or YAML, or any of the other 100 ways to dump out data. We used Data::Dumper because 11 years ago it was what there was.

Internally we use a variation of this codebase called simply "Debug". By default debug goes to STDOUT, but we have variants called debug_warn that goes to STDERR and a debug_dlog variant that will go directly to our perl based system logger.

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