X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=5460c8378f3377f87a1869dba9fc7bcd24ebe348;hb=9fef70e5fa3af77eb184ba08d47950b17406c945;hp=34fe41fc26ad6d6c90d4ed6138250c61d0fdd7f8;hpb=9cc51a42b5f5145b3d1e9ed89435b5377ebdd5fe;p=perl%2Fmodules%2FScope-Upper.git

diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 34fe41f..5460c83 100644
--- a/lib/Scope/Upper.pm
+++ b/lib/Scope/Upper.pm
@@ -9,13 +9,13 @@ Scope::Upper - Act on upper scopes.
 
 =head1 VERSION
 
-Version 0.16
+Version 0.18
 
 =cut
 
 our $VERSION;
 BEGIN {
- $VERSION = '0.16';
+ $VERSION = '0.18';
 }
 
 =head1 SYNOPSIS
@@ -24,7 +24,10 @@ L</reap>, L</localize>, L</localize_elem>, L</localize_delete> and L</WORDS> :
 
     package Scope;
 
-    use Scope::Upper qw<reap localize localize_elem localize_delete :words>;
+    use Scope::Upper qw<
+     reap localize localize_elem localize_delete
+     :words
+    >;
 
     sub new {
      my ($class, $name) = @_;
@@ -66,22 +69,22 @@ L</reap>, L</localize>, L</localize_elem>, L</localize_delete> and L</WORDS> :
     package UserLand;
 
     {
-     Scope->new("top");      # initializes $UserLand::tag
+     Scope->new("top");    # initializes $UserLand::tag
 
      {
       Scope->catch;
-      my $one = 1 + undef;   # prints "top: Use of uninitialized value..."
+      my $one = 1 + undef; # prints "top: Use of uninitialized value..."
 
       {
        Scope->private;
        eval { require Cwd };
-       print $@;             # prints "Can't locate Cwd.pm in @INC (@INC contains:) at..."
-      }
+       print $@;           # prints "Can't locate Cwd.pm in @INC
+      }                    #         (@INC contains:) at..."
 
-      require Cwd;           # loads Cwd.pm
+      require Cwd;         # loads Cwd.pm
      }
 
-    }                        # prints "top: done"
+    }                      # prints "top: done"
 
 L</unwind> and L</want_at> :
 
@@ -128,6 +131,28 @@ L</uplevel> :
 
     target('hello'); # "hello from Uplevel::target()"
 
+L</uid> and L</validate_uid> :
+
+    use Scope::Upper qw<uid validate_uid>;
+
+    my $uid;
+
+    {
+     $uid = uid();
+     {
+      if ($uid eq uid(UP)) { # yes
+       ...
+      }
+      if (validate_uid($uid)) { # yes
+       ...
+      }
+     }
+    }
+
+    if (validate_uid($uid)) { # no
+     ...
+    }
+
 =head1 DESCRIPTION
 
 This module lets you defer actions I<at run-time> that will take place when the control flow returns into an upper scope.
@@ -149,7 +174,11 @@ return values immediately to an upper level with L</unwind>, and know which cont
 
 =item *
 
-execute a subroutine in the context of an upper subroutine stack frame with L</uplevel>.
+execute a subroutine in the setting of an upper subroutine stack frame with L</uplevel> ;
+
+=item *
+
+uniquely identify contextes with L</uid> and L</validate_uid>.
 
 =back
 
@@ -168,11 +197,18 @@ BEGIN {
  XSLoader::load(__PACKAGE__, $VERSION);
 }
 
-=head2 C<reap $callback, $context>
+=head2 C<reap>
+
+    reap { ... };
+    reap { ... } $context;
+    &reap($callback, $context);
 
 Adds 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>
+
+    localize $what, $value;
+    localize $what, $value, $context;
 
 Introduces a C<local> delayed to the time of first return into the upper scope denoted by C<$context>.
 C<$what> can be :
@@ -222,7 +258,10 @@ Although I believe it shouldn't be a problem as glob slots definedness is pretty
 
 =back
 
-=head2 C<localize_elem $what, $key, $value, $context>
+=head2 C<localize_elem>
+
+    localize_elem $what, $key, $value;
+    localize_elem $what, $key, $value, $context;
 
 Introduces a C<local $what[$key] = $value> or C<local $what{$key} = $value> delayed to the time of first return into the upper scope denoted by C<$context>.
 Unlike L</localize>, C<$what> must be a string and the type of localization is inferred from its sigil.
@@ -254,7 +293,10 @@ C<$key> is ignored.
 
 =back
 
-=head2 C<unwind @values, $context>
+=head2 C<unwind>
+
+    unwind @values;
+    unwind @values, $context;
 
 Returns C<@values> I<from> the context pointed by C<$context>, i.e. from the subroutine, eval or format at or just above C<$context>, and immediately restart the program flow at this point - thus effectively returning to an upper scope.
 
@@ -270,7 +312,10 @@ This means that
 will set C<$num> to C<'z'>.
 You can use L</want_at> to handle these cases.
 
-=head2 C<want_at $context>
+=head2 C<want_at>
+
+    my $want = want_at;
+    my $want = want_at $context;
 
 Like C<wantarray>, but for the subroutine/eval/format at or just above C<$context>.
 
@@ -286,6 +331,11 @@ will rightfully set C<$num> to C<26>.
 
 =head2 C<uplevel $code, @args, $context>
 
+    my @ret = uplevel { ...; return @ret };
+    my @ret = uplevel { my @args = @_; ...; return @ret } @args;
+    my @ret = uplevel { ... } @args, $context;
+    my @ret = &uplevel($callback, @args, $context);
+
 Executes the code reference C<$code> with arguments C<@args> as if it were located at the subroutine stack frame pointed by C<$context>, effectively fooling C<caller> and C<die> into believing that the call actually happened higher in the stack.
 The code is executed in the context of the C<uplevel> call, and what it returns is returned as-is by C<uplevel>.
 
@@ -300,7 +350,7 @@ The code is executed in the context of the C<uplevel> call, and what it returns
     }
 
     my @inverses = target(1, 2, 4); # @inverses contains (0, 0.5, 0.25)
-    my $count    = target(1, 2, 4); # $target is 3
+    my $count    = target(1, 2, 4); # $count is 3
 
 L<Sub::Uplevel> also implements a pure-Perl version of C<uplevel>.
 Both are identical, with the following caveats :
@@ -310,7 +360,7 @@ Both are identical, with the following caveats :
 =item *
 
 The L<Sub::Uplevel> implementation of C<uplevel> may execute a code reference in the context of B<any> upper stack frame.
-The L<Scope::Upper> version only allows to uplevel to a B<subroutine> stack frame, and will croak if you try to target an C<eval> or a format.
+The L<Scope::Upper> version can only uplevel to a B<subroutine> stack frame, and will croak if you try to target an C<eval> or a format.
 
 =item *
 
@@ -336,7 +386,7 @@ will print "inner block: wut..." with L<Sub::Uplevel> and "outer block: wut..."
 
 =item *
 
-L<Sub::Uplevel> globally overrides C<CORE::GLOBAL::caller>, while L<Scope::Upper> does not.
+L<Sub::Uplevel> globally overrides the Perl keyword C<caller>, while L<Scope::Upper> does not.
 
 =back
 
@@ -353,6 +403,78 @@ A simple wrapper lets you mimic the interface of L<Sub::Uplevel/uplevel> :
 
 Albeit the three exceptions listed above, it passes all the tests of L<Sub::Uplevel>.
 
+=head2 C<uid>
+
+    my $uid = uid;
+    my $uid = uid $context;
+
+Returns an unique identifier (UID) for the context (or dynamic scope) pointed by C<$context>, or for the current context if C<$context> is omitted.
+This UID will only be valid for the life time of the context it represents, and another UID will be generated next time the same scope is executed.
+
+    my $uid;
+
+    {
+     $uid = uid;
+     if ($uid eq uid()) { # yes, this is the same context
+      ...
+     }
+     {
+      if ($uid eq uid()) { # no, we are one scope below
+       ...
+      }
+      if ($uid eq uid(UP)) { # yes, UP points to the same scope as $uid
+       ...
+      }
+     }
+    }
+
+    # $uid is now invalid
+
+    {
+     if ($uid eq uid()) { # no, this is another block
+      ...
+     }
+    }
+
+For example, each loop iteration gets its own UID :
+
+    my %uids;
+
+    for (1 .. 5) {
+     my $uid = uid;
+     $uids{$uid} = $_;
+    }
+
+    # %uids has 5 entries
+
+The UIDs are not guaranteed to be numbers, so you must use the C<eq> operator to compare them.
+
+To check whether a given UID is valid, you can use the L</validate_uid> function.
+
+=head2 C<validate_uid>
+
+    my $is_valid = validate_uid $uid;
+
+Returns true if and only if C<$uid> is the UID of a currently valid context (that is, it designates a scope that is higher than the current one in the call stack).
+
+    my $uid;
+
+    {
+     $uid = uid();
+     if (validate_uid($uid)) { # yes
+      ...
+     }
+     {
+      if (validate_uid($uid)) { # yes
+       ...
+      }
+     }
+    }
+
+    if (validate_uid($uid)) { # no
+     ...
+    }
+
 =head1 CONSTANTS
 
 =head2 C<SU_THREADSAFE>
@@ -365,10 +487,14 @@ True iff the module could have been built when thread-safety features.
 
 =head3 C<TOP>
 
+    my $top_context = TOP;
+
 Returns the context that currently represents the highest scope.
 
 =head3 C<HERE>
 
+    my $current_context = HERE;
+
 The context of the current scope.
 
 =head2 Getting a context from a context
@@ -376,16 +502,25 @@ The context of the current scope.
 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>
+=head3 C<UP>
+
+    my $upper_context = UP;
+    my $upper_context = UP $from;
 
 The context of the scope just above C<$from>.
 
-=head3 C<SUB $from>
+=head3 C<SUB>
+
+    my $sub_context = SUB;
+    my $sub_context = 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>
+=head3 C<EVAL>
+
+    my $eval_context = EVAL;
+    my $eval_context = 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>.
@@ -395,11 +530,17 @@ Note that C<$from> is returned if it is already an eval context ; hence C<EVAL E
 Here, C<$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>
+=head3 C<SCOPE>
+
+    my $context = SCOPE;
+    my $context = SCOPE $level;
 
 The C<$level>-th upper context, regardless of its type.
 
-=head3 C<CALLER $level>
+=head3 C<CALLER>
+
+    my $context = CALLER;
+    my $context = CALLER $level;
 
 The context of the C<$level>-th upper subroutine/eval/format.
 It kind of corresponds to the context represented by C<caller $level>, but while e.g. C<caller 0> refers to the caller context, C<CALLER 0> will refer to the top scope in the current context.
@@ -414,13 +555,13 @@ Where L</reap> fires depending on the C<$cxt> :
        {
         reap \&cleanup => $cxt;
         ...
-       }     # $cxt = SCOPE(0), or HERE
+       }     # $cxt = SCOPE(0) = HERE
        ...
-      }->(); # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0)
+      }->(); # $cxt = SCOPE(1) = UP = SUB = CALLER(0)
       ...
-     };      # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1)
+     };      # $cxt = SCOPE(2) = UP UP =  UP SUB = EVAL = CALLER(1)
      ...
-    }->();   # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2)
+    }->();   # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
     ...
 
 Where L</localize>, L</localize_elem> and L</localize_delete> act depending on the C<$cxt> :
@@ -430,19 +571,19 @@ Where L</localize>, L</localize_elem> and L</localize_delete> act depending on t
       sub {
        {
         localize '$x' => 1 => $cxt;
-        # $cxt = SCOPE(0), or HERE
+        # $cxt = SCOPE(0) = HERE
         ...
        }
-       # $cxt = SCOPE(1), or UP, or SUB, or CALLER, or CALLER(0)
+       # $cxt = SCOPE(1) = UP = SUB = CALLER(0)
        ...
       }->();
-      # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1)
+      # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1)
       ...
      };
-     # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2)
+     # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
      ...
     }->();
-    # $cxt = SCOPE(4), UP SUB UP SUB, or UP SUB EVAL, or UP CALLER(2), or TOP
+    # $cxt = SCOPE(4), UP SUB UP SUB = UP SUB EVAL = UP CALLER(2) = TOP
     ...
 
 Where L</unwind>, L</want_at> and L</uplevel> point to depending on the C<$cxt>:
@@ -451,19 +592,19 @@ Where L</unwind>, L</want_at> and L</uplevel> point to depending on the C<$cxt>:
      eval {
       sub {
        {
-        unwind @things => $cxt;     # or uplevel { ... } $cxt;
+        unwind @things => $cxt;   # or uplevel { ... } $cxt;
         ...
        }
        ...
-      }->(); # $cxt = SCOPE(0 .. 1), or HERE, or UP, or SUB, or CALLER(0)
+      }->(); # $cxt = SCOPE(0) = SCOPE(1) = HERE = UP = SUB = CALLER(0)
       ...
-     };      # $cxt = SCOPE(2), or UP UP, or UP SUB, or EVAL, or CALLER(1) (*)
+     };      # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1) (*)
      ...
-    }->();   # $cxt = SCOPE(3), or SUB UP SUB, or SUB EVAL, or CALLER(2)
+    }->();   # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
     ...
 
     # (*) Note that uplevel() will croak if you pass that scope frame,
-    #     because it can't target eval scopes.
+    #     because it cannot target eval scopes.
 
 =head1 EXPORT
 
@@ -484,6 +625,7 @@ our %EXPORT_TAGS = (
   localize localize_elem localize_delete
   unwind want_at
   uplevel
+  uid validate_uid
  > ],
  words  => [ qw<TOP HERE UP SUB EVAL SCOPE CALLER> ],
  consts => [ qw<SU_THREADSAFE> ],
@@ -520,6 +662,29 @@ However, it's possible to hook the end of the current scope compilation with L<B
 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-related fixes.
 
+Calling C<goto> to replace an L</uplevel>'d code frame does not work :
+
+=over 4
+
+=item *
+
+for a C<perl> older than the 5.8 series ;
+
+=item *
+
+for a C<DEBUGGING> C<perl> run with debugging flags set (as in C<perl -D ...>) ;
+
+=item *
+
+when the runloop callback is replaced by another module.
+
+=back
+
+In those three cases, L</uplevel> will look for a C<goto &sub> statement in its callback and, if there is one, throw an exception before executing the code.
+
+Moreover, in order to handle C<goto> statements properly, L</uplevel> currently has to suffer a run-time overhead proportional to the size of the the callback in every case (with a small ratio), and proportional to the size of B<all> the code executed as the result of the L</uplevel> call (including subroutine calls inside the callback) when a C<goto> statement is found in the L</uplevel> callback.
+Despite this shortcoming, this XS version of L</uplevel> should still run way faster than the pure-Perl version from L<Sub::Uplevel>.
+
 =head1 DEPENDENCIES
 
 L<XSLoader> (standard since perl 5.006).
@@ -530,13 +695,13 @@ L<perlfunc/local>, L<perlsub/"Temporary Values via local()">.
 
 L<Alias>, L<Hook::Scope>, L<Scope::Guard>, L<Guard>.
 
+L<Sub::Uplevel>.
+
 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.
 
 L<Scope::Escape>.
 
-L<Sub::Uplevel> provides a pure-Perl implementation of L</uplevel>.
-
 =head1 AUTHOR
 
 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
@@ -564,7 +729,7 @@ Thanks to Shawn M. Moore for motivation.
 
 =head1 COPYRIGHT & LICENSE
 
-Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010,2011,2012 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.