A better explaination of how string symbols work

[perl/modules/Scope-Upper.git] / lib / Scope / Upper.pm

diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 1570300323addcc83a51eff22d463d3ee7496f42..91219ff91e5b7fcd63cf1027d022412d35bce5d1 100644 (file)
--- a/lib/Scope/Upper.pm
+++ b/lib/Scope/Upper.pm
@@ -9,13 +9,13 @@ Scope::Upper - Act on upper scopes.
 
 =head1 VERSION
 
-Version 0.06
+Version 0.10
 
 =cut
 
 our $VERSION;
 BEGIN {
- $VERSION = '0.06';
+ $VERSION = '0.10';
 }
 
 =head1 SYNOPSIS
@@ -72,7 +72,9 @@ BEGIN {
     sub zap {
      try {
       return @things; # returns to try() and then outside zap()
+      # not reached
      }
+     # not reached
     }
 
     my @what = zap(); # @what contains @things
@@ -115,7 +117,7 @@ BEGIN {
 
 =head2 C<reap $callback, $context>
 
-Add a destructor that calls C<$callback> when the upper scope represented by C<$context> ends.
+Add a destructor that calls C<$callback> (in void context) when the upper scope represented by C<$context> ends.
 
 =head2 C<localize $what, $value, $context>
 
@@ -142,11 +144,23 @@ 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
+Thus, if the symbol name is not qualified, it will refer to the variable in the package where the localization actually takes place and not in the one where the C<localize> call was compiled.
+For example,
 
-    sub tag { localize '$x', $_[0] => UP }
+    {
+     package Scope;
+     sub new { localize '$tag', $_[0] => UP }
+    }
+
+    {
+     package Tool;
+     {
+      Scope->new;
+      ...
+     }
+    }
 
-will localize in the caller's namespace.
+will localize C<$Tool::tag> and not C<$Scope::tag>.
 
 =back
 
@@ -189,6 +203,7 @@ This means that
     my $num = sub {
      my @a = ('a' .. 'z');
      unwind @a => HERE;
+     # not reached
     }->();
 
 will set C<$num> to C<'z'>.
@@ -203,9 +218,16 @@ The previous example can then be "corrected" :
     my $num = sub {
      my @a = ('a' .. 'z');
      unwind +(want_at(HERE) ? @a : scalar @a) => HERE;
+     # not reached
     }->();
 
-will righteously set C<$num> to C<26>.
+will rightfully set C<$num> to C<26>.
+
+=head1 CONSTANTS
+
+=head2 C<SU_THREADSAFE>
+
+True iff the module could have been built when thread-safety features.
 
 =head1 WORDS
 
@@ -231,10 +253,12 @@ The context of the scope just above C<$from>.
 =head3 C<SUB $from>
 
 The context of the closest subroutine above C<$from>.
+Note that C<$from> is returned if it is already a subroutine context ; hence C<SUB SUB == SUB>.
 
 =head3 C<EVAL $from>
 
 The context of the closest eval above C<$from>.
+Note that C<$from> is returned if it is already an eval context ; hence C<EVAL EVAL == EVAL>.
 
 =head2 Getting a context from a level
 
@@ -312,6 +336,8 @@ Where L</unwind> and L</want_at> point to depending on the C<$cxt>:
 
 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'>.
 
+The constant L</SU_THREADSAFE> is also only exported on request, individually or by the tags C<':consts'> 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
@@ -320,8 +346,9 @@ use base qw/Exporter/;
 
 our @EXPORT      = ();
 our %EXPORT_TAGS = (
- funcs => [ qw/reap localize localize_elem localize_delete unwind want_at/ ],
- words => [ qw/TOP HERE UP SUB EVAL SCOPE CALLER/ ],
+ funcs  => [ qw/reap localize localize_elem localize_delete unwind want_at/ ],
+ words  => [ qw/TOP HERE UP SUB EVAL SCOPE CALLER/ ],
+ consts => [ qw/SU_THREADSAFE/ ],
 );
 our @EXPORT_OK   = map { @$_ } values %EXPORT_TAGS;
 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
@@ -363,6 +390,9 @@ L<XSLoader> (standard since perl 5.006).
 
 L<Alias>, L<Hook::Scope>, L<Scope::Guard>, L<Guard>.
 
+L<Continuation::Escape> is a thin wrapper around L<Scope::Upper> that gives you a continuation passing style interface to L</unwind>.
+It's easier to use, but it requires you to have control over the scope where you want to return.
+
 =head1 AUTHOR
 
 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
@@ -371,7 +401,8 @@ You can contact me by mail or on C<irc.perl.org> (vincent).
 
 =head1 BUGS
 
-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.
+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.
 
 =head1 SUPPORT
 
@@ -389,7 +420,7 @@ Thanks to Shawn M. Moore for motivation.
 
 =head1 COPYRIGHT & LICENSE
 
-Copyright 2008-2009 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010 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.