=head1 VERSION
-Version 0.03
+Version 0.05
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.03';
+ $VERSION = '0.05';
}
=head1 SYNOPSIS
package X;
- use Scope::Upper qw/reap localize localize_elem localize_delete/;
+ use Scope::Upper qw/reap localize localize_elem localize_delete UP/;
sub desc { shift->{desc} }
my ($desc) = @_;
# First localize $x so that it gets destroyed last
- localize '$x' => bless({ desc => $desc }, __PACKAGE__) => 1;
+ localize '$x' => bless({ desc => $desc }, __PACKAGE__) => 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";
- } => 1;
+ } => UP;
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;
+ } => UP;
- localize_delete '@ARGV', $#ARGV => 1; # delete last @ARGV element
+ localize_delete '@ARGV', $#ARGV => UP; # delete last @ARGV element
}
package Y;
...
} # "pie: done" is printed
+ package Z;
+
+ use Scope::Upper qw/unwind want_at :words/;
+
+ sub try (&) {
+ my @result = shift->();
+ my $cx = SUB UP SUB;
+ unwind +(want_at($cx) ? @result : scalar @result) => $cx;
+ }
+
+ ...
+
+ sub zap {
+ try {
+ return @things; # returns to try() and then outside zap()
+ }
+ }
+
+ my @what = zap(); # @what contains @things
+
=head1 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, 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.
+
+=head2 C<CALLER $stack>
+
+The level of the C<$stack>-th upper subroutine/eval/format context.
+It kind of corresponds to the context represented by C<caller $stack>, but while e.g. C<caller 0> refers to the caller context, C<CALLER 0> will refer to the top scope in the current context.
=head1 FUNCTIONS
If the sigil is C<'$'>, L</localize> follows the same syntax as C<local $x = $value>, i.e. C<$value> isn't dereferenced.
For example,
- localize '$x', \'foo' => 0;
+ localize '$x', \'foo' => HERE;
will set C<$x> to a reference to the string C<'foo'>.
Other sigils (C<'@'>, C<'%'>, C<'&'> and C<'*'>) require C<$value> to be a reference of the corresponding type.
When the symbol is given by a string, it is resolved when the actual localization takes place and not when C<localize> is called.
This means that
- sub tag { localize '$x', $_[0] => 1; }
+ sub tag { localize '$x', $_[0] => UP }
will localize in the caller's namespace.
=head2 C<unwind @values, $level>
Returns C<@values> I<from> the context indicated by C<$level>, i.e. from the subroutine, eval or format just above C<$level>.
-The upper level isn't coerced onto C<@values>, which is hence always evaluated in list context.
-
-=head2 C<want_at $level>
-
-Like C<wantarray>, but for the subroutine/eval/format context just above C<$level>.
-
-=head1 WORDS
-
-=head2 C<TOP>
-
-Returns the level that currently represents the highest scope.
-
-=head2 C<HERE>
-The current level - i.e. C<0>.
-
-=head2 C<UP $from>
-
-The level of the scope just above C<$from>.
-
-=head2 C<DOWN $from>
-
-The level of the scope just below C<$from>.
+The upper level isn't coerced onto C<@values>, which is hence always evaluated in list context.
+This means that
-=head2 C<SUB $from>
+ my $num = sub {
+ my @a = ('a' .. 'z');
+ unwind @a => HERE;
+ }->();
-The level of the closest subroutine context above C<$from>.
+will set C<$num> to C<'z'>.
+You can use L</want_at> to handle these cases.
-=head2 C<EVAL $from>
+=head2 C<want_at $level>
-The level of the closest eval context above C<$from>.
+Like C<wantarray>, but for the subroutine/eval/format context just above C<$level>.
-If C<$from> is omitted in any of those functions, the current level is used as the reference level.
+The previous example can then be "corrected" :
-=head2 C<CALLER $stack>
+ my $num = sub {
+ my @a = ('a' .. 'z');
+ unwind +(want_at(HERE) ? @a : scalar @a) => HERE;
+ }->();
-The level corresponding to the stack referenced by C<caller $stack>.
+will righteously set C<$num> to C<26>.
=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'>.
-Same goes for the words L</TOP>, L</HERE>, L</UP>, L</DOWN>, L</SUB>, L</EVAL> and L</CALLER> that are only exported on request, individually or by the tags C<':words'> and C<':all'>.
+Same goes for the words L</TOP>, L</HERE>, L</UP>, L</SUB>, L</EVAL>, L</SCOPE> and L</CALLER> that are only exported on request, individually or by the tags C<':words'> and C<':all'>.
=cut
our @EXPORT = ();
our %EXPORT_TAGS = (
funcs => [ qw/reap localize localize_elem localize_delete unwind want_at/ ],
- words => [ qw/TOP HERE UP DOWN SUB EVAL CALLER/ ],
+ words => [ qw/TOP HERE UP SUB EVAL SCOPE CALLER/ ],
);
our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
$EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
local $x = 0;
{
- reap sub { print $x } => 0;
+ reap sub { print $x } => HERE;
local $x = 1;
...
}
...
{
local $x = 1;
- reap sub { $x = 2 } => 0;
+ reap sub { $x = 2 } => HERE;
...
}
# $x is 0
projects / perl / modules / Scope-Upper.git / blobdiff