8 Scope::Upper - Act on upper scopes.
25 use Scope::Upper qw/reap localize localize_elem/;
27 sub desc { shift->{desc} }
32 # First localize $x so that it gets destroyed last
33 localize '$x' => bless({ desc => $desc }, __PACKAGE__) => 1;
37 my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
38 print $x->desc . ": done\n";
41 localize_elem '%SIG', '__WARN__' => sub {
43 my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
44 CORE::warn($x->desc . ': ' . join('', @_));
52 # $x is now a X object
53 warn 'what'; # warns "pie: what at ..."
55 } # "pie: done" is printed
59 This module lets you defer actions that will take place when the control flow returns into an upper scope.
60 Currently, you can hook an upper scope end, or localize variables and array/hash values in higher contexts.
68 XSLoader::load(__PACKAGE__, $VERSION);
71 =head2 C<reap $callback, $level>
73 Add a destructor that calls C<$callback> when the C<$level>-th upper scope ends, where C<0> corresponds to the current scope.
75 =head2 C<localize $what, $value, $level>
77 A C<local> delayed to the time of first return into the C<$level>-th upper scope.
84 A glob, in which case C<$value> can either be a glob or a reference.
85 L</localize> follows then the same syntax as C<local *x = $value>.
86 For example, if C<$value> is a scalar reference, then the C<SCALAR> slot of the glob will be set to C<$$value> - just like C<local *x = \1> sets C<$x> to C<1>.
90 A string beginning with a sigil, representing the symbol to localize and to assign to.
91 If the sigil is C<'$'>, L</localize> follows the same syntax as C<local $x = $value>, i.e. C<$value> isn't dereferenced.
94 localize '$x', \'foo' => 0;
96 will set C<$x> to a reference to the string C<'foo'>.
97 Other sigils (C<'@'>, C<'%'>, C<'&'> and C<'*'>) require C<$value> to be a reference of the corresponding type.
99 When the symbol is given by a string, it is resolved when the actual localization takes place and not when C<localize> is called.
102 sub tag { localize '$x', $_[0] => 1; }
104 will localize in the caller's namespace.
108 =head2 C<localize_elem $what, $key, $value, $level>
110 Similar to L</localize> but for array and hash elements.
111 If C<$what> is a glob, the slot to fill is determined from which type of reference C<$value> is ; otherwise it's inferred from the sigil.
112 C<$key> is either an array index or a hash key, depending of which kind of variable you localize.
116 Returns the level that currently represents the highest scope.
120 The functions L</reap>, L</localize>, L</localize_elem> and L</TOPLEVEL> are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
124 use base qw/Exporter/;
128 funcs => [ qw/reap localize localize_elem TOPLEVEL/ ],
130 our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
131 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
135 L<XSLoader> (standard since perl 5.006).
139 L<Alias>, L<Hook::Scope>, L<Scope::Guard>, L<Guard>.
143 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
145 You can contact me by mail or on C<irc.perl.org> (vincent).
149 Please report any bugs or feature requests to C<bug-scope-upper at rt.cpan.org>, or through the web interface at L<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.
153 You can find documentation for this module with the perldoc command.
157 =head1 ACKNOWLEDGEMENTS
159 Inspired by Ricardo Signes.
161 =head1 COPYRIGHT & LICENSE
163 Copyright 2008 Vincent Pit, all rights reserved.
165 This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
169 1; # End of Scope::Upper