Whenever you've got this kind of problem (which is common in event-driven systems) the easiest solution is generally to use a closure:

   $self->{twig} = new XML::Twig(twig_handlers =>
                                    {
                                     tag => sub { 
                                               my ($twig,$tag) = @_;  
+                              
                                               $self->tagHandler($tag)
+;
                                            }

                                     });
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Note that the anonymous sub closes over the $self in the outer scope. Closures are extremely useful; you owe it to yourself to read up on them.

here's an introductionary article on closures.

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