| Subject: | Getting a "Modification of non-creatable array value attempted, subscript -1" |
The following code causes Devel::TraceSubs (v0.02) to die a horrible death. It's my own fault, so I can work around it to get D::TS to work. Thus, non-urgent. I've had a look at the code but I don't see an easy way to fix it. I would consider it sufficient to merely warn of the failure mode (Don't Do That Then!) in the documentation.
The nastiness is in the guts subroutine. In real life, Devel::DProf showed that it was a considerably hot, so I save a certain amount of time by not setting up a $self lexical, and deferencing $_[0] directly.
The exact error message is
Modification of non-creatable array value attempted, subscript -1 at /usr/local/lib/perl5/site_perl/5.8.7/Devel/TraceSubs.pm line 116.
You can run the script as ./try to get it to run normally, or ./try 1 to make it crash (this simply sets the params attribute of the D::TS object.
__BEGIN__
#! /usr/local/bin/perl -w
package P;
use strict;
sub new { bless { p => [qw[ foo ]] }, 'P' }
sub guts { $_[0]->{p}; }
package main;
use strict;
use Devel::TraceSubs;
my $dbg = Devel::TraceSubs->new( params => shift || 0 )->trace( 'P::' );
print P->new->guts, "\n";
__END__