package X;
- use Scope::Upper qw/reap localize localize_elem localize_delete UP/;
+ use Scope::Upper qw/reap localize localize_elem localize_delete :words/;
sub desc { shift->{desc} }
my ($desc) = @_;
# First localize $x so that it gets destroyed last
- localize '$x' => bless({ desc => $desc }, __PACKAGE__) => UP;
+ localize '$x' => bless({ desc => $desc }, __PACKAGE__) => UP; # one scope up
reap sub {
my $pkg = caller;
my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
print $x->desc . ": done\n";
- } => UP;
+ } => SCOPE 1; # same as UP here
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('', @_));
- } => UP;
+ } => UP CALLER 0; # same as UP here
- localize_delete '@ARGV', $#ARGV => UP; # delete last @ARGV element
+ # delete last @ARGV element
+ localize_delete '@ARGV', -1 => UP SUB HERE; # same as UP here
}
package Y;
Currently, you can hook an upper scope end, or localize variables, array/hash values or deletions of elements in higher contexts.
You can also return to an upper level and know which context was in use then.
-=head1 WORDS
-
-These control words are to be used to indicate the target scope.
-
-=head2 C<TOP>
-
-Returns the level that currently represents the highest scope.
-
-=head2 C<HERE>
-
-The current level.
-
-=head2 C<UP $from>
-
-The level of the scope just above C<$from>.
-
-=head2 C<SUB $from>
-
-The level of the closest subroutine context above C<$from>.
-
-=head2 C<EVAL $from>
-
-The level of the closest eval context above C<$from>.
-
-If C<$from> is omitted in any of those functions, the current level is used as the reference level.
-
-=head2 C<SCOPE $stack>
-
-The C<$stack>-th upper frame.
+=head1 FUNCTIONS
-=head2 C<CALLER $stack>
+In all those functions, C<$context> refers to the target scope.
-The level of the C<$stack>-th upper subroutine/eval/format context.
-It kind of corresponds to the context represented by C<caller $stack>, but while e.g. C<caller 0> refers to the caller context, C<CALLER 0> will refer to the top scope in the current context.
+You have to use one or a combination of L</WORDS> to build the C<$context> to pass to these functions.
+This is needed in order to ensure that the module still works when your program is ran in the debugger.
+Don't try to use a raw value or things will get messy.
-=head1 FUNCTIONS
+The only thing you can assume is that it is an I<absolute> indicator of the frame.
+This means that you can safely store it at some point and use it when needed, and it will still denote the original scope.
=cut
XSLoader::load(__PACKAGE__, $VERSION);
}
-=head2 C<reap $callback, $level>
+=head2 C<reap $callback, $context>
-Add a destructor that calls C<$callback> when the C<$level>-th upper scope ends, where C<0> corresponds to the current scope.
+Add a destructor that calls C<$callback> when the upper scope represented by C<$context> ends.
-=head2 C<localize $what, $value, $level>
+=head2 C<localize $what, $value, $context>
-A C<local> delayed to the time of first return into the C<$level>-th upper scope.
+A C<local> delayed to the time of first return into the upper scope denoted by C<$context>.
C<$what> can be :
=over 4
=back
-=head2 C<localize_elem $what, $key, $value, $level>
+=head2 C<localize_elem $what, $key, $value, $context>
Similar to L</localize> but for array and hash elements.
If C<$what> is a glob, the slot to fill is determined from which type of reference C<$value> is ; otherwise it's inferred from the sigil.
C<$key> is either an array index or a hash key, depending of which kind of variable you localize.
-=head2 C<localize_delete $what, $key, $level>
+=head2 C<localize_delete $what, $key, $context>
Similiar to L</localize>, but for deleting variables or array/hash elements.
C<$what> can be:
=back
-=head2 C<unwind @values, $level>
+=head2 C<unwind @values, $context>
-Returns C<@values> I<from> the context indicated by C<$level>, i.e. from the subroutine, eval or format just above C<$level>.
+Returns C<@values> I<from> the context pointed by C<$context>, i.e. from the subroutine, eval or format just above C<$context>.
-The upper level isn't coerced onto C<@values>, which is hence always evaluated in list context.
+The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context.
This means that
my $num = sub {
will set C<$num> to C<'z'>.
You can use L</want_at> to handle these cases.
-=head2 C<want_at $level>
+=head2 C<want_at $context>
-Like C<wantarray>, but for the subroutine/eval/format context just above C<$level>.
+Like C<wantarray>, but for the subroutine/eval/format just above C<$context>.
The previous example can then be "corrected" :
will righteously set C<$num> to C<26>.
+=head1 WORDS
+
+=head2 Constants
+
+=head3 C<TOP>
+
+Returns the context that currently represents the highest scope.
+
+=head3 C<HERE>
+
+The context of the current scope.
+
+=head2 Getting a context from a context
+
+For any of those functions, C<$from> is expected to be a context.
+When omitted, it defaults to the the current context.
+
+=head3 C<UP $from>
+
+The context of the scope just above C<$from>.
+
+=head3 C<SUB $from>
+
+The context of the closest subroutine above C<$from>.
+
+=head3 C<EVAL $from>
+
+The context of the closest eval above C<$from>.
+
+=head2 Getting a context from a level
+
+Here, C<$level> should denote a number of scopes above the current one.
+When omitted, it defaults to C<0> and those functions return the same context as L</HERE>.
+
+=head3 C<SCOPE $level>
+
+The C<$level>-th upper context, regardless of its type.
+
+=head3 C<CALLER $level>
+
+The context of the C<$level>-th upper subroutine/eval/format.
+It kind of corresponds to the context represented by C<caller $level>, but while e.g. C<caller 0> refers to the caller context, C<CALLER 0> will refer to the top scope in the current context.
+
=head1 EXPORT
The functions L</reap>, L</localize>, L</localize_elem>, L</localize_delete>, L</unwind> and L</want_at> are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
L</reap>, L</localize> and L</localize_elem> effects can't cross C<BEGIN> blocks, hence calling those functions in C<import> is deemed to be useless.
This is an hopeless case because C<BEGIN> blocks are executed once while localizing constructs should do their job at each run.
+Some rare oddities may still happen when running inside the debugger.
+It may help to use a perl higher than 5.8.9 or 5.10.0, as they contain some context fixes.
+
=head1 DEPENDENCIES
L<XSLoader> (standard since perl 5.006).
Inspired by Ricardo Signes.
+Thanks to Shawn M. Moore for motivation.
+
=head1 COPYRIGHT & LICENSE
Copyright 2008-2009 Vincent Pit, all rights reserved.
projects / perl / modules / Scope-Upper.git / commitdiff