check in what change#1182 didn't, and Changes

p4raw-link: @1182 on //depot/perl: c7c9307cc294d88bccf6b755e886fdee7d955ee0

p4raw-id: //depot/perl@1212

2 files changed, 36 insertions, 0 deletions

diff --git a/pod/perlre.pod b/pod/perlre.pod
index b8c566228a..ebd58582d0 100644
--- a/pod/perlre.pod
+++ b/pod/perlre.pod
@@ -329,6 +329,36 @@ Experimental "evaluate any Perl code" zero-width assertion.  Always
 succeeds.  C<code> is not interpolated.  Currently the rules to
 determine where the C<code> ends are somewhat convoluted.
 
+The C<code> is properly scoped in the following sense: if the assertion
+is backtracked (compare L<"Backtracking">), all the changes introduced after
+C<local>isation are undone, so
+
+  $_ = 'a' x 8;
+  m< 
+     (?{ $cnt = 0 })			# Initialize $cnt.
+     (
+       a 
+       (?{
+           local $cnt = $cnt + 1;	# Update $cnt, backtracking-safe.
+       })
+     )*  
+     aaaa
+     (?{ $res = $cnt })			# On success copy to non-localized
+					# location.
+   >x;
+
+will set C<$res = 4>.  Note that after the match $cnt returns to the globally
+introduced value 0, since the scopes which restrict C<local> statements
+are unwound.
+
+This assertion may be used as L<C<(?(condition)yes-pattern|no-pattern)>>
+switch.  If I<not> used in this way, the result of evaluation of C<code>
+is put into variable $^R.  This happens immediately, so $^R can be used from
+other C<(?{ code })> assertions inside the same regular expression.
+
+The above assignment to $^R is properly localized, thus the old value of $^R
+is restored if the assertion is backtracked (compare L<"Backtracking">).
+
 B<WARNING>: This is a grave security risk for arbitrarily interpolated
 patterns.  It introduces security holes in previously safe programs.
 A fix to Perl, and to this documentation, will be forthcoming prior
diff --git a/pod/perlvar.pod b/pod/perlvar.pod
index d10fe35cbd..2ed3e97f77 100644
--- a/pod/perlvar.pod
+++ b/pod/perlvar.pod
@@ -717,6 +717,12 @@ Start with single-step on.
 Note that some bits may be relevent at compile-time only, some at
 run-time only. This is a new mechanism and the details may change.
 
+=item $^R
+
+The result of evaluation of the last successful L<perlre/C<(?{ code })>> 
+regular expression assertion.  (Excluding those used as switches.)  May
+be written to.
+
 =item $^S
 
 Current state of the interpreter.  Undefined if parsing of the current