comment on

B::Xref (lanx beat me to mentioning it; I was fiddling with a POC).

#!/usr/bin/env perl

my $fb = fizzbuzz();
print "$_\n" for @$fb;

sub fizzbuzz {
    my ($n, $m) = (1, 100);
    my @out;
    for my $num ($n .. $m) {
        my $line = '';
        $line .= 'fizz' if $num % 3 == 0;
        $line .= 'buzz' if $num % 5 == 0;
        push @out, $line || $num;
    }
    return \@out;
}
[download]

When you run this with B::Xref you get the following:

perl -MO=Xref mytest.pl

File mytest.pl
  Subroutine (definitions)
    Package Internals
      &SvREADONLY       s0
      &SvREFCNT         s0
      &V                s0
      &getcwd           s0
      &hv_clear_placeholders  s0
    Package PerlIO
      &get_layers       s0
    Package Regexp
      &DESTROY          s2147483647
    Package Tie::Hash::NamedCapture
      &CLEAR            s0
      &DELETE           s0
      &EXISTS           s0
      &FETCH            s0
      &FIRSTKEY         s0
      &NEXTKEY          s0
      &SCALAR           s0
      &STORE            s0
      &TIEHASH          s0
      &_tie_it          s0
      &flags            s0
    Package UNIVERSAL
      &DOES             s0
      &VERSION          s0
      &can              s0
      &isa              s0
    Package constant
      &_make_const      s0
    Package main
      &fizzbuzz         s3
    Package mro
      &method_changed_in  s0
    Package re
      &is_regexp        s0
      &regexp_pattern   s0
      &regname          s0
      &regnames         s0
      &regnames_count   s0
    Package version
      &(""              s0
      &()               s0
      &(*               s0
      &(*=              s0
      &(+               s0
      &(+=              s0
      &(-               s0
      &(-=              s0
      &(/               s0
      &(/=              s0
      &(0+              s0
      &(<=>             s0
      &(abs             s0
      &(bool            s0
      &(cmp             s0
      &(nomethod        s0
      &_VERSION         s0
      &boolean          s0
      &declare          s0
      &is_alpha         s0
      &is_qv            s0
      &new              s0
      &noop             s0
      &normal           s0
      &numify           s0
      &parse            s0
      &qv               s0
      &stringify        s0
      &vcmp             s0
  Subroutine (main)
    Package (lexical)
      $fb               i3, 4
      @$fb              4
    Package main
      $_                4
      &fizzbuzz         &3
  Subroutine fizzbuzz
    Package (lexical)
      $line             i10, 13
      $m                i7, 9
      $n                i7, 9
      $num              11, 12, 13
      @out              i8, 13, 15
mytest.pl syntax OK
[download]

The numbers you see all over the place are where some entity appears. So $line first appears on line 10, and again on line 13, for example. As you layer in other modules such as strict, warnings, or others that are actually substantial, the output grows considerably. But things are fairly well categorized, so if you know what package to look within, you'll find what you're after. I actually removed use strict and use warnings just to produce output that was more useful in this post.

Dave

In reply to Re: Visualize Perl Program by davido
in thread Visualize Perl Program by aartist

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