Change 18293 by jhi@lyta on 2002/12/12 13:57:56
Resolve [#perl 15774] by fiat: simply document that
\C in lookbehind is unsupported.
Affected files ...
... //depot/maint-5.8/perl/pod/perlre.pod#3 edit
... //depot/maint-5.8/perl/pod/perlretut.pod#2 edit
Differences ...
==== //depot/maint-5.8/perl/pod/perlre.pod#3 (text) ====
Index: perl/pod/perlre.pod
--- perl/pod/perlre.pod#2~18080~ Sun Nov 3 21:23:04 2002
+++ perl/pod/perlre.pod Thu Dec 12 05:57:56 2002
@@ -188,6 +188,7 @@
\C Match a single C char (octet) even under Unicode.
NOTE: breaks up characters into their UTF-8 bytes,
so you may end up with malformed pieces of UTF-8.
+ Unsupported in lookbehind.
A C<\w> matches a single alphanumeric character (an alphabetic
character, or a decimal digit) or C<_>, not a whole word. Use C<\w+>
==== //depot/maint-5.8/perl/pod/perlretut.pod#2 (text) ====
Index: perl/pod/perlretut.pod
--- perl/pod/perlretut.pod#1~17645~ Fri Jul 19 12:29:57 2002
+++ perl/pod/perlretut.pod Thu Dec 12 05:57:56 2002
@@ -1707,7 +1707,7 @@
The last regexp matches, but is dangerous because the string
I<character> position is no longer synchronized to the string I<byte>
position. This generates the warning 'Malformed UTF-8
-character'. C<\C> is best used for matching the binary data in strings
+character'. The C<\C> is best used for matching the binary data in strings
with binary data intermixed with Unicode characters.
Let us now discuss the rest of the character classes. Just as with
@@ -2003,6 +2003,10 @@
$x =~ /foo(?!bar)/; # doesn't match, 'bar' follows 'foo'
$x =~ /foo(?!baz)/; # matches, 'baz' doesn't follow 'foo'
$x =~ /(?<!\s)foo/; # matches, there is no \s before 'foo'
+
+The C<\C> is unsupported in lookbehind, because the already
+treacherous definition of C<\C> would become even more so
+when going backwards.
=head2 Using independent subexpressions to prevent backtracking
End of Patch.
