If this is in a module, i usually add a _debug key to my blessed hash and use a function with a name similar to dbg("Message"). All this function does is :
sub dbg {
  my ($self,$msg) = @_;
  return if (! $self->{_debug});
  print STDERR "[DEBUG] : $msg\n";
}

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And, a simple accessor method like : 
sub debug {
  my ($self,$val) = @_;
  $self->{_debug} = $val if (defined $val);
  $self->{_debug};
}

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While this all may seem a bit elaborate, it is excedingly useful to have as a standard for every module. If the $main::DEBUG is the approach you prefer, there is always more than one way to do it, and changing dbg to the following would work :
sub dbg {
  my $msg = shift;
  print "[DEBUG] : $msg\n" if ($main::DEBUG);
}

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OH, a sarcasm detector, that’s really useful

In reply to Re: Debugging in packages by MZSanford
in thread Debugging in packages by agoth

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