/ 
Manip-END-0.04
River stage zero No dependents
/ Manip::END

NAME

Manip::END - Mess around with END blocks

SYNOPSIS

  use Manip::END qw( clear_end_array set_end_array );

  clear_end_array();

  set_end_array(sub {...}, sub {...});

  $ends = Manip::END->new;

  $ends->unshift(sub {...}, sub {...});

  $ends->remove_class("My::Class");

	$ends->remove_isa("My::Base::Class");

	$ends->filter_sub(sub {
		my $pkg = shift;
		return $pkg =~ /^MyModule::/ ? 0 : 1;
	});

DESCRIPTION

Perl keeps an array of subroutines that should be run just before your program exits (see perlmod manpage for more details). This module allows you to manipulte this array.

WARNING

This module gives you access to one of Perl's internal arrays that you're not supposed to see so there are a couple of funny things going on.

The array contains an undef for each END blcok that has been encountered, it's not really an undef though, it's a kind of raw coderef that's not wrapped in a scalar ref. This leads to fun error messages like

Bizarre copy of CODE in sassign

when you try to assign one of these values to another variable. This all means that it's somewhere between difficult and impossible to manipulate these values array yourself. Use the filter functions provided.

That said, you can erase them without any problem and you can add your own coderefs without any problem too. If you want to selectively remove items from the array, that's where the fun begins. You cannot do

@$ref = grep {...} @$ref

if any of the undef coderefs will survive the grep as they will cause an error such as the one above.

HOW TO USE IT

The most useful thing you can do with it is to remove certain END blocks based on the package they belong to. To do you can do something like

  my $ends = Manip::END->new;

	$ends->filter_sub(sub {
		my $pkg = shift;
		return $pkg =~ /^MyModule::/ ? 0 : 1;
	});

This will remove any element of the array where the routine was declared in a pakcage that begins with "MyModule::". So none of the END blocks from that package will return when your program finishes up.

EXPORTED FUNCTIONS

clear_end_array()

This will clear the array of END blocks.

set_end_array(@blocks)

@blocks is an array of subroutine references. This will set the array of END blocks.

CONSTRUCTOR

Manip::END->new()

This will return a blessed reference to the array of END blocks which you can manipulate yourself. You can maipulate the array directly but it's probably much better idea to to use the methods below.

OBJECT METHODS

$obj->unshift(@blocks)

@blocks is an array of references to code blocks. This will add the blocks to the start of the array. By adding to the start of the array, they will be the first code blocks executed by Perl when it is exiting

$obj->push(@blocks)

@blocks is an array of references to code blocks. This will add the blocks to the end of the array. By adding to the end of the array, they will be the last code blocks executed by Perl when it is exiting

$obj->clear()

This clears the array.

$obj->filter_sub($code)

$code is a reference to a subroutine. For each element of the array, this will execute the subroutine in $code. The first and only argument to the routine is the nameof the package in which the END block was declared. If the subroutine returns a true value, the element will be kept. If it returns false, the element will be removed from the array.

$obj->remove_isa($class)

$class is a string containing the name of a class. This removes all of the END blocks from packages which inherit from $class.

$obj->remove_pkg($pkg)

$pkg is a string containing the name of a package. This removes all of the END blocks from $pkg.

AUTHOR

Written by Fergal Daly <fergal@esatclear.ie>. Suggested by Mark Jason Dominus at his talk in Dublin.

LICENSE

Copyright 2003 by Fergal Daly <fergal@esatclear.ie>.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://www.perl.com/perl/misc/Artistic.html