2 Scope::Upper - Act on upper scopes.
10 use Scope::Upper qw/reap localize localize_elem/;
12 sub desc { shift->{desc} }
17 # First localize $x so that it gets destroyed last
18 localize '$x' => bless({ desc => $desc }, __PACKAGE__) => 1;
22 my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
23 print $x->desc . ": done\n";
26 localize_elem '%SIG', '__WARN__' => sub {
28 my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
29 CORE::warn($x->desc . ': ' . join('', @_));
37 # $x is now a X object
38 warn 'what'; # warns "pie: what at ..."
40 } # "pie: done" is printed
43 This module lets you defer actions that will take place when the control
44 flow returns into an upper scope. Currently, you can hook an upper scope
45 end, or localize variables and array/hash values in higher contexts.
48 "reap $callback, $level"
49 Add a destructor that calls $callback when the $level-th upper scope
50 ends, where 0 corresponds to the current scope.
52 "localize $what, $value, $level"
53 A "local" delayed to the time of first return into the $level-th upper
56 * A glob, in which case $value can either be a glob or a reference.
57 "localize" follows then the same syntax as "local *x = $value". For
58 example, if $value is a scalar reference, then the "SCALAR" slot of
59 the glob will be set to $$value - just like "local *x = \1" sets $x
62 * A string beginning with a sigil, representing the symbol to localize
63 and assign to. If the sigil is '$', then $value isn't dereferenced,
66 localize '$x', \'foo' => 0;
68 will set $x to a reference to the string 'foo'. Other sigils behave
69 as if a glob was passed.
71 The symbol is resolved when the actual localization takes place and
72 not when "localize" is called. This means that
74 sub tag { localize '$x', $_[0] => 1; }
76 will localize in the caller's namespace.
78 "localize_elem $what, $key, $value, $level"
79 Similar to "localize" but for array and hash elements. If $what is a
80 glob, the slot to fill is determined from which type of reference $value
81 is ; otherwise it's inferred from the sigil. $key is either an array
82 index or a hash key, depending of which kind of variable you localize.
85 Returns the level that currently represents the highest scope.
88 The functions "reap", "localize", "localize_elem" and "TOPLEVEL" are
89 only exported on request, either individually or by the tags ':funcs'
93 XSLoader (standard since perl 5.006).
96 Alias, Hook::Scope, Scope::Guard, Guard.
99 Vincent Pit, "<perl at profvince.com>", <http://www.profvince.com>.
101 You can contact me by mail or on "irc.perl.org" (vincent).
104 Please report any bugs or feature requests to "bug-scope-upper at
105 rt.cpan.org", or through the web interface at
106 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Scope-Upper>. I will be
107 notified, and then you'll automatically be notified of progress on your
108 bug as I make changes.
111 You can find documentation for this module with the perldoc command.
116 Inspired by Ricardo Signes.
119 Copyright 2008 Vincent Pit, all rights reserved.
121 This program is free software; you can redistribute it and/or modify it
122 under the same terms as Perl itself.