Devel::Symdump without Devel::Symdump interference

eXile has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I'm trying to write a testscript that will print all symbols that are used in another script like this:

symdump script1.pl 5 7
[download]

This will dump the symbol table after line 5 in the script and after line 7 in the script. This far I've come up with this:

#!/usr/bin/perl

use strict;
use warnings;
use Devel::Symdump;

$| = 1;

my $code;

my $program=shift @ARGV;
die ("usage: $0 <programname> <linenr.> [<linenr.>...]\n") unless ($pr
+ogram);
open (PRG, $program) or die "cant open '$program'\n";

my $symdumpcode = "
\$main::obj=Devel::Symdump->rnew('ThisIsAnotherPackageAndMostLikelyWil
+lNeverCollideWithAnyOtherNamespace'); 
print \$main::obj->as_string();
";

my $idx=0;
foreach my $arg (sort {$a <=> $b} @ARGV) {
    while (<PRG>) {
        $idx++;
        $code .= $_;
        last if ($arg == $idx and $code .= $symdumpcode);
    }
}
close PRG;

eval "package ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAny
+OtherNamespace;
$code";

print $@ if ($@);
[download]

This doesn't print any symbols for my testscripts. If I change the rnew('<longpackagename>') to rnew('main') it will print all symbols including the symbols used in Devel::Symdump. Tried using the diff method in Devel::Symdump but that does only show a diff (duh), so any packages used in my script AND in Devel::Symdump will not show up. What I could do is make 2 Symdump-objects, one of the eval-ed code, one of Devel::Symdump itself, and compare their as_string output manually (it's sorted already), but that doesn't help me understand why the above code doesn't work.

My questions:

Why does a Symdump on a package within the eval not show the symbols within that package? (I guess it's got something to do with compile vs. runtime but can't bend my brain around this one)
There must obviously be MTOWTDI (checking %main:: ?). Any ideas on how to do this simpler/better/more elegant? Any pointers to similar scripts (couldn't find any myself)?

Comment on Devel::Symdump without Devel::Symdump interference Select or Download Code

Replies are listed 'Best First'.
Re: Devel::Symdump without Devel::Symdump interference by broquaint (Abbot) on Apr 19, 2004 at 18:45 UTC
Seems to work ok here. My test file looks like this `no strict; # 1 # 2 # 3 # 4 sub foo { } # 5 @bar = \&foo; # 6 $baz = "a string"; # 7 %this = qw/une deux/; # 8 # 9 # 10` [download] And I get the following (unsightly) output arrays ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: bar functions ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: foo hashes ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: this ios packages scalars ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: BEGIN ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: bar ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: baz ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: foo ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: this unknowns arrays ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: bar functions ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: foo hashes ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: this ios packages scalars ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: BEGIN ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: bar ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: baz ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: foo ThisIsAnotherPackageAndMostLikelyWillNeverCollideWithAnyOtherN +amespace:: this [download] Also, your script will always slurp the number of lines as provided by the last argument, which would seem to be unintended behaviour. As for alternatives, you might want to look at `Data::Dumper` or the much more accurate `Data::Dumper::Streamer` for displaying the contents of a symbol table. HTH `_________ broquaint`	[reply] [d/l] [select]
Re: Re: Devel::Symdump without Devel::Symdump interference by eXile (Priest) on Apr 20, 2004 at 01:51 UTC
I'm sorry to not have posted my test scripts, but they were full of `my` and `strict`, opposed to your `no strict` test script. Do you (or anybody else) know why that matters in this case? I supposed the `my` variables were in scope of the package-with-the-long-name?	[reply] [d/l] [select]
Re: Re: Re: Devel::Symdump without Devel::Symdump interference by broquaint (Abbot) on Apr 20, 2004 at 01:57 UTC
I turned off strictures to comply with your `strict` code. As for `my` variables, see. Lexical scoping like a fox and Of Symbol Tables and Globs for further information on the difference between lexical variables and package variables (briefly, `my`ed variables won't be dumped). HTH `_________ broquaint`	[reply]