This is 0.10

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

diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 988254fa5016b804443464a1fbb23fb2067aa5d9..30f94547df8d937db1481de5b8bfdfa76e1ea1c0 100644 (file)
--- a/lib/Scope/Upper.pm
+++ b/lib/Scope/Upper.pm
@@ -9,13 +9,13 @@ Scope::Upper - Act on upper scopes.
 
 =head1 VERSION
 
 
 =head1 VERSION
 

-Version 0.05
+Version 0.10

 
 =cut
 
 our $VERSION;
 BEGIN {
 
 =cut
 
 our $VERSION;
 BEGIN {

- $VERSION = '0.05';
+ $VERSION = '0.10';

 }
 
 =head1 SYNOPSIS
 }
 
 =head1 SYNOPSIS


@@ -72,27 +72,41 @@ BEGIN {
     sub zap {
      try {
       return @things; # returns to try() and then outside zap()
     sub zap {
      try {
       return @things; # returns to try() and then outside zap()

+      # not reached

      }
      }

+     # not reached

     }
 
     my @what = zap(); # @what contains @things
 
 =head1 DESCRIPTION
 
     }
 
     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.
+This module lets you defer actions I<at run-time> that will take place when the control flow returns into an upper scope.
+Currently, you can:
+
+=over 4
+
+=item *
+
+hook an upper scope end with L</reap> ;
+
+=item *
+
+localize variables, array/hash values or deletions of elements in higher contexts with respectively L</localize>, L</localize_elem> and L</localize_delete> ;
+
+=item *
+
+return values immediately to an upper level with L</unwind>, and know which context was in use then with L</want_at>.
+
+=back

 
 =head1 FUNCTIONS
 
 In all those functions, C<$context> refers to the target scope.
 
 
 =head1 FUNCTIONS
 
 In all those functions, C<$context> refers to the target scope.
 

-You have to use one or a combination of L</WORDS> to build the C<$context> to pass to these functions.
+You have to use one or a combination of L</WORDS> to build the C<$context> passed to these functions.

 This is needed in order to ensure that the module still works when your program is ran in the debugger.
 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.
-
-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.
+The only thing you can assume is that it is an I<absolute> indicator of the frame, which means that you can safely store it at some point and use it when needed, and it will still denote the original scope.

 
 =cut
 
 
 =cut
 


@@ -103,7 +117,7 @@ BEGIN {
 
 =head2 C<reap $callback, $context>
 
 
 =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>
 
 
 =head2 C<localize $what, $value, $context>
 


@@ -169,7 +183,7 @@ C<$key> is ignored.
 
 =head2 C<unwind @values, $context>
 
 
 =head2 C<unwind @values, $context>
 

-Returns C<@values> I<from> the context pointed by C<$context>, i.e. from the subroutine, eval or format just above C<$context>.
+Returns C<@values> I<from> the context pointed by C<$context>, i.e. from the subroutine, eval or format just above C<$context>, and immediately restart the program flow at this point - thus effectively returning to (or from, depending on how you see it) an upper context.

 
 The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context.
 This means that
 
 The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context.
 This means that


@@ -177,6 +191,7 @@ This means that
     my $num = sub {
      my @a = ('a' .. 'z');
      unwind @a => HERE;
     my $num = sub {
      my @a = ('a' .. 'z');
      unwind @a => HERE;

+     # not reached

     }->();
 
 will set C<$num> to C<'z'>.
     }->();
 
 will set C<$num> to C<'z'>.


@@ -191,9 +206,16 @@ The previous example can then be "corrected" :
     my $num = sub {
      my @a = ('a' .. 'z');
      unwind +(want_at(HERE) ? @a : scalar @a) => HERE;
     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
 
 
 =head1 WORDS
 


@@ -219,10 +241,12 @@ The context of the scope just above C<$from>.
 =head3 C<SUB $from>
 
 The context of the closest subroutine 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>.
 
 =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
 
 
 =head2 Getting a context from a level
 


@@ -238,10 +262,70 @@ The C<$level>-th upper context, regardless of its type.
 The context of the C<$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.
 
 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.
 

+=head2 Examples
+
+Where L</reap> fires depending on the C<$cxt> :
+
+    sub {
+     eval {
+      sub {
+       {
+        reap \&cleanup => $cxt;
+        ...
+       }     # $cxt = SCOPE(0), or HERE
+       ...
+      }->(); # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0)
+      ...
+     };      # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1)
+     ...
+    }->();   # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2)
+    ...
+
+Where L</localize>, L</localize_elem> and L</localize_delete> act depending on the C<$cxt> :
+
+    sub {
+     eval {
+      sub {
+       {
+        localize '$x' => 1 => $cxt;
+        # $cxt = SCOPE(0), or HERE
+        ...
+       }
+       # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0)
+       ...
+      }->();
+      # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1)
+      ...
+     };
+     # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2)
+     ...
+    }->();
+    # $cxt = SCOPE(4), UP SUB UP SUB, or UP SUB EVAL, or UP CALLER(2), or TOP
+    ...
+
+Where L</unwind> and L</want_at> point to depending on the C<$cxt>:
+
+    sub {
+     eval {
+      sub {
+       {
+        unwind @things => $cxt;
+        ...
+       }
+       ...
+      }->(); # $cxt = SCOPE(0 .. 1), or HERE, or UP, or SUB, or CALLER(0)
+      ...
+     };      # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1)
+     ...
+    }->();   # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2)
+    ...
+

 =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'>.
 
 =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'>.
 

+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
 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


@@ -250,8 +334,9 @@ use base qw/Exporter/;
 
 our @EXPORT      = ();
 our %EXPORT_TAGS = (
 
 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;
 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
 );
 our @EXPORT_OK   = map { @$_ } values %EXPORT_TAGS;
 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];


@@ -278,11 +363,12 @@ Consider those examples:
 
 The first case is "solved" by moving the C<local> before the C<reap>, and the second by using L</localize> instead of L</reap>.
 
 
 The first case is "solved" by moving the C<local> before the C<reap>, and the second by using L</localize> instead of L</reap>.
 

-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.
+The effects of L</reap>, L</localize> and L</localize_elem> 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.
 This is an hopeless case because C<BEGIN> blocks are executed once while localizing constructs should do their job at each run.

+However, it's possible to hook the end of the current scope compilation with L<B::Hooks::EndOfScope>.

 
 Some rare oddities may still happen when running inside the debugger.
 
 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.
+It may help to use a perl higher than 5.8.9 or 5.10.0, as they contain some context-related fixes.

 
 =head1 DEPENDENCIES
 
 
 =head1 DEPENDENCIES
 


@@ -292,6 +378,9 @@ L<XSLoader> (standard since perl 5.006).
 
 L<Alias>, L<Hook::Scope>, L<Scope::Guard>, L<Guard>.
 
 
 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>.
 =head1 AUTHOR
 
 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.


@@ -318,7 +407,7 @@ Thanks to Shawn M. Moore for motivation.
 
 =head1 COPYRIGHT & LICENSE
 
 
 =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.
 
 
 This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.