Would your code work when run stand-alone? Have you printed out the code you're trying to eval? Have you looked at the error message and looked at what causes it?

The following change to your code might help you see the problem:

use diagnostics;
use warnings;
use strict;
use Data::Dumper;

my %h;
$h{ 'a' }{ 'b' } = 5;

my $b_code =<<'CODE';

sub tryme_b
{
   my $foo = shift;
   return ${ $foo }{ 'a' }{ 'b' };
}

CODE

my $c = "$b_code; tryme_b( \%h );";
my $ans = eval $c or die "[$c] doesn't work:$@";

print "b:$ans,\n";

[download]

Also, basic debugging in your tryme_b would also show you what goes wrong.

In reply to Re^3: How to interpret a string as perl code and execute it? by Corion
in thread How to interpret a string as perl code and execute it? by sg

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.