/ 
Scope-Upper-0.01
River stage two • 15 direct dependents • 48 total dependents
/ Scope::Upper

NAME

Scope::Upper - Act on upper scopes.

VERSION

Version 0.01

SYNOPSIS

package X;

use Scope::Upper qw/reap localize localize_elem/;

sub desc { shift->{desc} }

sub set_tag {
 my ($desc) = @_;

 # First localize $x so that it gets destroyed last
 localize '$x' => bless({ desc => $desc }, __PACKAGE__) => 1;

 reap sub {
  my $pkg = caller;
  my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
  print $x->desc . ": done\n";
 } => 1;

 localize_elem '%SIG', '__WARN__' => sub {
  my $pkg = caller;
  my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
  CORE::warn($x->desc . ': ' . join('', @_));
 } => 1;
}

package Y;

{
 X::set_tag('pie');
 # $x is now a X object
 warn 'what'; # warns "pie: what at ..."
 ...
} # "pie: done" is printed

DESCRIPTION

This module lets you defer actions that will take place when the control flow returns into an upper scope. Currently, you can hook an upper scope end, or localize variables and array/hash values in higher contexts.

FUNCTIONS

reap $callback, $level

Add a destructor that calls $callback when the $level-th upper scope ends, where 0 corresponds to the current scope.

localize $what, $value, $level

A local delayed to the time of first return into the $level-th upper scope. $what can be :

  • A glob, in which case $value can either be a glob or a reference. "localize" follows then the same syntax as local *x = $value. For example, if $value is a scalar reference, then the SCALAR slot of the glob will be set to $$value - just like local *x = \1 sets $x to 1.

  • A string beginning with a sigil, representing the symbol to localize and assign to. If the sigil is '$', then $value isn't dereferenced, that is

    localize '$x', \'foo' => 0;

    will set $x to a reference to the string 'foo'. Other sigils behave as if a glob was passed.

    The symbol is resolved when the actual localization takes place and not when localize is called. This means that

    sub tag { localize '$x', $_[0] => 1; }

    will localize in the caller's namespace.

localize_elem $what, $key, $value, $level

Similar to "localize" but for array and hash elements. If $what is a glob, the slot to fill is determined from which type of reference $value is ; otherwise it's inferred from the sigil. $key is either an array index or a hash key, depending of which kind of variable you localize.

TOPLEVEL

Returns the level that currently represents the highest scope.

EXPORT

The functions "reap", "localize", "localize_elem" and "TOPLEVEL" are only exported on request, either individually or by the tags ':funcs' and ':all'.

DEPENDENCIES

XSLoader (standard since perl 5.006).

SEE ALSO

Alias, Hook::Scope, Scope::Guard, Guard.

AUTHOR

Vincent Pit, <perl at profvince.com>, http://www.profvince.com.

You can contact me by mail or on irc.perl.org (vincent).

BUGS

Please report any bugs or feature requests to bug-scope-upper at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Scope-Upper. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Scope::Upper

ACKNOWLEDGEMENTS

Inspired by Ricardo Signes.

COPYRIGHT & LICENSE

Copyright 2008 Vincent Pit, all rights reserved.

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