X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=4fb21d543a3f1adcfb791adf73fe7c79c144f9c5;hb=e4bb8d889bcaaf2a3c9f1f9cd2a8185115db5db0;hp=083536422eba2dc3e1dc565041384cdcfff6dae3;hpb=bac4fc46c2d48ce5db75de6c88e0983aeeedf865;p=perl%2Fmodules%2FScope-Upper.git diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm index 0835364..4fb21d5 100644 --- a/lib/Scope/Upper.pm +++ b/lib/Scope/Upper.pm @@ -9,20 +9,20 @@ Scope::Upper - Act on upper scopes. =head1 VERSION -Version 0.01 +Version 0.05 =cut our $VERSION; BEGIN { - $VERSION = '0.01'; + $VERSION = '0.05'; } =head1 SYNOPSIS package X; - use Scope::Upper qw/reap localize localize_elem/; + use Scope::Upper qw/reap localize localize_elem localize_delete/; sub desc { shift->{desc} } @@ -43,21 +43,44 @@ BEGIN { my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope CORE::warn($x->desc . ': ' . join('', @_)); } => 1; + + localize_delete '@ARGV', $#ARGV => 1; # delete last @ARGV element } package Y; { X::set_tag('pie'); - # $x is now a X object + # $x is now a X object, and @ARGV has one element less warn 'what'; # warns "pie: what at ..." ... } # "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) => $cx; + } + + ... + + sub zap { + try { + return @things; # returns to try() and then outside zap() + } + } + + my @what = zap(); # @what contains @things + =head1 DESCRIPTION This module lets you defer actions that will take place when the control flow returns into an upper scope. -Currently, you can hook an upper scope end, or localize variables and array/hash values in higher contexts. +Currently, you can hook an upper scope end, or localize variables, array/hash values or deletions of elements in higher contexts. +You can also return to an upper level and know which context was in use then. =head1 FUNCTIONS @@ -87,15 +110,16 @@ For example, if C<$value> is a scalar reference, then the C slot of the =item * -A string beginning with a sigil, representing the symbol to localize and assign to. -If the sigil is C<'$'>, then C<$value> isn't dereferenced, that is +A string beginning with a sigil, representing the symbol to localize and to assign to. +If the sigil is C<'$'>, L follows the same syntax as C, i.e. C<$value> isn't dereferenced. +For example, localize '$x', \'foo' => 0; will set C<$x> to a reference to the string C<'foo'>. -Other sigils behave as if a glob was passed. +Other sigils (C<'@'>, C<'%'>, C<'&'> and C<'*'>) require C<$value> to be a reference of the corresponding type. -The symbol is resolved when the actual localization takes place and not when C is called. +When the symbol is given by a string, it is resolved when the actual localization takes place and not when C is called. This means that sub tag { localize '$x', $_[0] => 1; } @@ -110,13 +134,100 @@ Similar to L but for array and hash elements. If C<$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 +=head2 C + +Similiar to L, but for deleting variables or array/hash elements. +C<$what> can be: + +=over 4 + +=item * + +A glob, in which case C<$key> is ignored and the call is equivalent to C. + +=item * + +A string beginning with C<'@'> or C<'%'>, for which the call is equivalent to respectiveley C and C. + +=item * + +A string beginning with C<'&'>, which more or less does C in the upper scope. +It's actually more powerful, as C<&func> won't even C anymore. +C<$key> is ignored. + +=back + +=head2 C + +Returns C<@values> I the context indicated by C<$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. +This means that + + my $num = sub { + my @a = ('a' .. 'z'); + unwind @a => 0; + }->(); + +will set C<$num> to C<'z'>. +You can use L to handle these cases. + +=head2 C + +Like C, but for the subroutine/eval/format context just above C<$level>. + +The previous example can then be "corrected" : + + my $num = sub { + my @a = ('a' .. 'z'); + unwind +(want_at(0) ? @a : scalar @a) => 0; + }->(); + +will righteously set C<$num> to C<26>. + +=head1 WORDS + +=head2 C Returns the level that currently represents the highest scope. +=head2 C + +The current level - i.e. C<0>. + +=head2 C + +The level of the scope just above C<$from>. + +=head2 C + +The level of the scope just below C<$from>. + +=head2 C + +The level of the closest subroutine context above C<$from>. + +=head2 C + +The level of the closest eval context above C<$from>. + +If C<$from> is omitted in any of those functions, the current level is used as the reference level. + +=head2 C + +The level of the C<$stack>-th upper subroutine/eval/format context. +It kind of corresponds to the context represented by C, but while e.g. C refers to the caller context, C will refer to the top scope in the current context. +For example, + + reap ... => CALLER(0) + +will fire the destructor when the current subroutine/eval/format ends. + =head1 EXPORT -The functions L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>. +The functions L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>. + +Same goes for the words L, L, L, L, L, L and L that are only exported on request, individually or by the tags C<':words'> and C<':all'>. =cut @@ -124,11 +235,37 @@ use base qw/Exporter/; our @EXPORT = (); our %EXPORT_TAGS = ( - funcs => [ qw/reap localize localize_elem TOPLEVEL/ ], + funcs => [ qw/reap localize localize_elem localize_delete unwind want_at/ ], + words => [ qw/TOP HERE UP DOWN SUB EVAL CALLER/ ], ); our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS; $EXPORT_TAGS{'all'} = [ @EXPORT_OK ]; +=head1 CAVEATS + +Be careful that local variables are restored in the reverse order in which they were localized. +Consider those examples: + + local $x = 0; + { + reap sub { print $x } => 0; + local $x = 1; + ... + } + # prints '0' + ... + { + local $x = 1; + reap sub { $x = 2 } => 0; + ... + } + # $x is 0 + +The first case is "solved" by moving the C before the C, and the second by using L instead of L. + +L, L and L effects can't cross C blocks, hence calling those functions in C is deemed to be useless. +This is an hopeless case because C blocks are executed once while localizing constructs should do their job at each run. + =head1 DEPENDENCIES L (standard since perl 5.006). @@ -153,13 +290,15 @@ You can find documentation for this module with the perldoc command. perldoc Scope::Upper +Tests code coverage report is available at L. + =head1 ACKNOWLEDGEMENTS Inspired by Ricardo Signes. =head1 COPYRIGHT & LICENSE -Copyright 2008 Vincent Pit, all rights reserved. +Copyright 2008-2009 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.