X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FScope%2FUpper.pm;h=b114f2f0130e6faa46309a6d41c0e6260cd1888c;hb=780a9a13dd0a14aabed9c7c91613d4ad75190c9f;hp=4a9010059f7ce5112af17d57452539ae17458ff8;hpb=be1d59463692da1b5ef787aeffd0aedbef65664e;p=perl%2Fmodules%2FScope-Upper.git

diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 4a90100..b114f2f 100644
--- a/lib/Scope/Upper.pm
+++ b/lib/Scope/Upper.pm
@@ -1,5 +1,7 @@
 package Scope::Upper;
 
+use 5.006_001;
+
 use strict;
 use warnings;
 
@@ -9,13 +11,13 @@ Scope::Upper - Act on upper scopes.
 
 =head1 VERSION
 
-Version 0.19
+Version 0.31
 
 =cut
 
 our $VERSION;
 BEGIN {
- $VERSION = '0.19';
+ $VERSION = '0.31';
 }
 
 =head1 SYNOPSIS
@@ -170,7 +172,11 @@ localize variables, array/hash values or deletions of elements in higher context
 
 =item *
 
-return values immediately to an upper level with L</unwind>, L</yield> and L</leave>, and know which context was in use then with L</want_at> ;
+return values immediately to an upper level with L</unwind>, L</yield> and L</leave> ;
+
+=item *
+
+gather information about an upper context with L</want_at> and L</context_info> ;
 
 =item *
 
@@ -178,7 +184,7 @@ execute a subroutine in the setting of an upper subroutine stack frame with L</u
 
 =item *
 
-uniquely identify contextes with L</uid> and L</validate_uid>.
+uniquely identify contexts with L</uid> and L</validate_uid>.
 
 =back
 
@@ -286,7 +292,7 @@ A glob, in which case C<$key> is ignored and the call is equivalent to C<local *
 
 =item *
 
-A string beginning with C<'@'> or C<'%'>, for which the call is equivalent to respectiveley C<local $a[$key]; delete $a[$key]> and C<local $h{$key}; delete $h{$key}>.
+A string beginning with C<'@'> or C<'%'>, for which the call is equivalent to respectively C<local $a[$key]; delete $a[$key]> and C<local $h{$key}; delete $h{$key}>.
 
 =item *
 
@@ -301,7 +307,7 @@ C<$key> is ignored.
     unwind;
     unwind @values, $context;
 
-Returns C<@values> I<from> the subroutine, eval or format context pointed by or just above C<$context>, and immediately restart the program flow at this point - thus effectively returning C<@values> to an upper scope.
+Returns C<@values> I<from> the subroutine, eval or format context pointed by or just above C<$context>, and immediately restarts the program flow at this point - thus effectively returning C<@values> to an upper scope.
 If C<@values> is empty, then the C<$context> parameter is optional and defaults to the current context (making the call equivalent to a bare C<return;>) ; otherwise it is mandatory.
 
 The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context.
@@ -321,7 +327,7 @@ You can use L</want_at> to handle these cases.
     yield;
     yield @values, $context;
 
-Returns C<@values> I<from> the context pointed by or just above C<$context>, and immediately restart the program flow at this point.
+Returns C<@values> I<from> the context pointed by or just above C<$context>, and immediately restarts the program flow at this point.
 If C<@values> is empty, then the C<$context> parameter is optional and defaults to the current context ; otherwise it is mandatory.
 
 L</yield> differs from L</unwind> in that it can target I<any> upper scope (besides a C<s///e> substitution context) and not necessarily a sub, an eval or a format.
@@ -339,6 +345,7 @@ Hence you can use it to return values from a C<do> or a C<map> block :
     } @things;
 
 Like for L</unwind>, the upper context isn't coerced onto C<@values>.
+You can use the fifth value returned by L</context_info> to handle context coercion.
 
 =head2 C<leave>
 
@@ -346,16 +353,18 @@ Like for L</unwind>, the upper context isn't coerced onto C<@values>.
     leave @values;
 
 Immediately returns C<@values> from the current block, whatever it may be (besides a C<s///e> substitution context).
-C<leave> is actually a synonym for C<unwind HERE>, while C<leave @values> is a synonym for C<yield @values, HERE>.
+C<leave> is actually a synonym for C<yield HERE>, while C<leave @values> is a synonym for C<yield @values, HERE>.
+
+Like for L</yield>, you can use the fifth value returned by L</context_info> to handle context coercion.
 
 =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<$context>.
+Like L<perlfunc/wantarray>, but for the subroutine, eval or format context located at or just above C<$context>.
 
-The previous example can then be "corrected" :
+It can be used to revise the example showed in L</unwind> :
 
     my $num = sub {
      my @a = ('a' .. 'z');
@@ -365,6 +374,65 @@ The previous example can then be "corrected" :
 
 will rightfully set C<$num> to C<26>.
 
+=head2 C<context_info>
+
+    my ($package, $filename, $line, $subroutine, $hasargs,
+        $wantarray, $evaltext, $is_require, $hints, $bitmask,
+        $hinthash) = context_info $context;
+
+Gives information about the context denoted by C<$context>, akin to what L<perlfunc/caller> provides but not limited only to subroutine, eval and format contexts.
+When C<$context> is omitted, it defaults to the current context.
+
+The returned values are, in order :
+
+=over 4
+
+=item *
+
+I<(index 0)> : the namespace in use when the context was created ;
+
+=item *
+
+I<(index 1)> : the name of the file at the point where the context was created ;
+
+=item *
+
+I<(index 2)> : the line number at the point where the context was created ;
+
+=item *
+
+I<(index 3)> : the name of the subroutine called for this context, or C<undef> if this is not a subroutine context ;
+
+=item *
+
+I<(index 4)> : a boolean indicating whether a new instance of C<@_> was set up for this context, or C<undef> if this is not a subroutine context ;
+
+=item *
+
+I<(index 5)> : the context (in the sense of L<perlfunc/wantarray>) in which the context (in our sense) is executed ;
+
+=item *
+
+I<(index 6)> : the contents of the string being compiled for this context, or C<undef> if this is not an eval context ;
+
+=item *
+
+I<(index 7)> : a boolean indicating whether this eval context was created by C<require>, or C<undef> if this is not an eval context ;
+
+=item *
+
+I<(index 8)> : the value of the lexical hints in use when the context was created ;
+
+=item *
+
+I<(index 9)> : a bit string representing the warnings in use when the context was created ;
+
+=item *
+
+I<(index 10)> : a reference to the lexical hints hash in use when the context was created (only on perl 5.10 or greater).
+
+=back
+
 =head2 C<uplevel>
 
     my @ret = uplevel { ...; return @ret };
@@ -537,7 +605,7 @@ The context of the current scope.
 =head2 Getting a context from a context
 
 For any of those functions, C<$from> is expected to be a context.
-When omitted, it defaults to the the current context.
+When omitted, it defaults to the current context.
 
 =head3 C<UP>
 
@@ -545,6 +613,7 @@ When omitted, it defaults to the the current context.
     my $upper_context = UP $from;
 
 The context of the scope just above C<$from>.
+If C<$from> points to the top-level scope in the current stack, then a warning is emitted and C<$from> is returned (see L</DIAGNOSTICS> for details).
 
 =head3 C<SUB>
 
@@ -552,7 +621,8 @@ The context of the scope just above C<$from>.
     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>.
+If C<$from> already designates a subroutine context, then it is returned as-is ; hence C<SUB SUB == SUB>.
+If no subroutine context is present in the call stack, then a warning is emitted and the current context is returned (see L</DIAGNOSTICS> for details).
 
 =head3 C<EVAL>
 
@@ -560,7 +630,8 @@ Note that C<$from> is returned if it is already a subroutine context ; hence C<S
     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>.
+If C<$from> already designates an eval context, then it is returned as-is ; hence C<EVAL EVAL == EVAL>.
+If no eval context is present in the call stack, then a warning is emitted and the current context is returned (see L</DIAGNOSTICS> for details).
 
 =head2 Getting a context from a level
 
@@ -573,6 +644,7 @@ When omitted, it defaults to C<0> and those functions return the same context as
     my $context = SCOPE $level;
 
 The C<$level>-th upper context, regardless of its type.
+If C<$level> points above the top-level scope in the current stack, then a warning is emitted and the top-level context is returned (see L</DIAGNOSTICS> for details).
 
 =head3 C<CALLER>
 
@@ -581,6 +653,7 @@ 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 $level>, but while e.g. C<caller 0> refers to the caller context, C<CALLER 0> will refer to the top scope in the current context.
+If C<$level> points above the top-level scope in the current stack, then a warning is emitted and the top-level context is returned (see L</DIAGNOSTICS> for details).
 
 =head2 Examples
 
@@ -623,7 +696,7 @@ Where L</localize>, L</localize_elem> and L</localize_delete> act depending on t
     # $cxt = SCOPE(4), UP SUB UP SUB = UP SUB EVAL = UP CALLER(2) = TOP
     ...
 
-Where L</unwind>, L</yield>, L</want_at> and L</uplevel> point to depending on the C<$cxt>:
+Where L</unwind>, L</yield>, L</want_at>, L</context_info> and L</uplevel> point to depending on the C<$cxt>:
 
     sub {
      eval {
@@ -644,9 +717,22 @@ Where L</unwind>, L</yield>, L</want_at> and L</uplevel> point to depending on t
     # (*) Note that uplevel() will croak if you pass that scope frame,
     #     because it cannot target eval scopes.
 
+=head1 DIAGNOSTICS
+
+=head2 C<Cannot target a scope outside of the current stack>
+
+This warning is emitted when L</UP>, L</SCOPE> or L</CALLER> end up pointing to a context that is above the top-level context of the current stack.
+It indicates that you tried to go higher than the main scope, or to point across a C<DESTROY> method, a signal handler, an overloaded or tied method call, a C<require> statement or a C<sort> callback.
+In this case, the resulting context is the highest reachable one.
+
+=head2 C<No targetable %s scope in the current stack>
+
+This warning is emitted when you ask for an L</EVAL> or L</SUB> context and no such scope can be found in the call stack.
+The resulting context is the current one.
+
 =head1 EXPORT
 
-The functions L</reap>, L</localize>, L</localize_elem>, L</localize_delete>,  L</unwind>, L</yield>, L</leave>, L</want_at> and L</uplevel> are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
+The functions L</reap>, L</localize>, L</localize_elem>, L</localize_delete>,  L</unwind>, L</yield>, L</leave>, L</want_at>, L</context_info> and L</uplevel> 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'>.
 
@@ -662,7 +748,7 @@ our %EXPORT_TAGS = (
   reap
   localize localize_elem localize_delete
   unwind yield leave
-  want_at
+  want_at context_info
   uplevel
   uid validate_uid
  > ],
@@ -674,6 +760,8 @@ $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
 
 =head1 CAVEATS
 
+It is not possible to act upon a scope that belongs to another perl 'stack', i.e. to target a scope across a C<DESTROY> method, a signal handler, an overloaded or tied method call, a C<require> statement or a C<sort> callback.
+
 Be careful that local variables are restored in the reverse order in which they were localized.
 Consider those examples:
 
@@ -721,17 +809,20 @@ when the runloop callback is replaced by another module.
 
 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.
+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 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>.
 
+Starting from C<perl> 5.19.4, it is unfortunately no longer possible to reliably throw exceptions from L</uplevel>'d code while the debugger is in use.
+This may be solved in a future version depending on how the core evolves.
+
 =head1 DEPENDENCIES
 
-L<perl> 5.6.
+L<perl> 5.6.1.
 
 A C compiler.
 This module may happen to build with a C++ compiler as well, but don't rely on it, as no guarantee is made in this regard.
 
-L<XSLoader> (core since perl 5.006).
+L<XSLoader> (core since perl 5.6.0).
 
 =head1 SEE ALSO
 
@@ -748,7 +839,7 @@ L<Scope::Escape>.
 
 =head1 AUTHOR
 
-Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
+Vincent Pit C<< <vpit at cpan.org> >>.
 
 You can contact me by mail or on C<irc.perl.org> (vincent).
 
@@ -763,17 +854,18 @@ You can find documentation for this module with the perldoc command.
 
     perldoc Scope::Upper
 
-Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Scope-Upper>.
-
 =head1 ACKNOWLEDGEMENTS
 
 Inspired by Ricardo Signes.
 
+The reimplementation of a large part of this module for perl 5.24 was provided by David Mitchell.
+His work was sponsored by the Perl 5 Core Maintenance Grant from The Perl Foundation.
+
 Thanks to Shawn M. Moore for motivation.
 
 =head1 COPYRIGHT & LICENSE
 
-Copyright 2008,2009,2010,2011,2012 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019 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.