In perl.git, the branch blead has been updated
<http://perl5.git.perl.org/perl.git/commitdiff/dc92530577ed67345a2e69b1f6631d95899e47f9?hp=cac3df65afe2fed9ad80147a24b5ae6ea601a609>
- Log -----------------------------------------------------------------
commit dc92530577ed67345a2e69b1f6631d95899e47f9
Author: Karl Williamson <pub...@khwilliamson.com>
Date: Tue Jan 18 17:23:23 2011 -0700
perlre.pod: corrections for /a
-----------------------------------------------------------------------
Summary of changes:
pod/perlre.pod | 32 +++++++++++++++++++++-----------
1 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/pod/perlre.pod b/pod/perlre.pod
index 39840fc..4b058a2 100644
--- a/pod/perlre.pod
+++ b/pod/perlre.pod
@@ -631,6 +631,10 @@ These modifiers do not carry over into named subpatterns
called in the
enclosing group. In other words, a pattern such as C<((?i)(&NAME))> does not
change the case-sensitivity of the "NAME" pattern.
+Any of these modifiers can be set to apply globally to all regular
+expressions compiled within the scope of a C<use re>. See
+L<re/'/flags' mode>.
+
Starting in Perl 5.14, a C<"^"> (caret or circumflex accent) immediately
after the C<"?"> is a shorthand equivalent to C<d-imsx>. Flags (except
C<"d">) may follow the caret to override it.
@@ -659,7 +663,7 @@ Latin-1 (ISO-8859-1) meanings (which are the same as
Unicode's), whereas
in strict ASCII their meanings are undefined. Thus the platform
effectively becomes a Unicode platform. The ASCII characters remain as
ASCII characters (since ASCII is a subset of Latin-1 and Unicode). For
-example, when this option is XXX not on, on a non-utf8 string, C<"\w">
+example, when this option is not on, on a non-utf8 string, C<"\w">
matches precisely C<[A-Za-z0-9_]>. When the option is on, it matches
not just those, but all the Latin-1 word characters (such as an "n" with
a tilde). On EBCDIC platforms, which already are equivalent to Latin-1,
@@ -670,15 +674,21 @@ small letters C<MU>; otherwise not; and the C<LATIN
CAPITAL LETTER SHARP
S> will match any of C<SS>, C<Ss>, C<sS>, and C<ss>, otherwise not.
(This last case is buggy, however.)
-C<"a"> is the same as C<"u">, but C<\d>, C<\s>, C<\w>, and the Posix
-character classes are restricted to matching in the ASCII range only.
-That is, with this modifier, C<\d> always means precisely the digits
-C<"0"> to C<"9">; C<\s> means the five characters C<[ \f\n\r\t]>;
-C<\w> means the 53 characters C<[A-Za-z0-9_]>; and likewise, all the
+C<"a"> is the same as C<"u">, except that C<\d>, C<\s>, C<\w>, and the
+Posix character classes are restricted to matching in the ASCII range
+only. That is, with this modifier, C<\d> always means precisely the
+digits C<"0"> to C<"9">; C<\s> means the five characters C<[ \f\n\r\t]>;
+C<\w> means the 63 characters C<[A-Za-z0-9_]>; and likewise, all the
Posix classes such as C<[[:print:]]> match only the appropriate
ASCII-range characters. As you would expect, this modifier causes, for
-example, C<\D> to mean the same thing as C<[^0-9]>. C<"a"> behaves the
-same as C<"u"> with regards to case-insensitive matches. XXX
+example, C<\D> to mean the same thing as C<[^0-9]>; in fact, all
+non-ASCII characters match C<\D>, C<\S>, and C<\W>. C<\b> still means
+to match at the boundary between C<\w> and C<\W>, using the C<"a">
+definitions of them (similarly for C<\B>). Otherwise, C<"a"> behaves
+like the C<"u"> modifier, in that case-insensitive matching uses Unicode
+semantics; for example, "k" will match the Unicode C<\N{KELVIN SIGN}>
+under C</i> matching, and code points in the Latin1 range, above ASCII
+will have Unicode semantics when it comes to case-insensitive matching.
C<"d"> means to use the traditional Perl pattern matching behavior.
This is dualistic (hence the name C<"d">, which also could stand for
@@ -692,9 +702,9 @@ default if the regular expression is compiled neither
within the scope
of a C<"use locale"> pragma nor a <C<"use feature 'unicode_strings">
pragma.
-Note that the C<d>, C<l>, C<p>, and C<u> modifiers are special in that
-they can only be enabled, not disabled, and the C<d>, C<l>, and C<u>
-modifiers are mutually exclusive: specifying one de-specifies the
+Note that the C<a>, C<d>, C<l>, C<p>, and C<u> modifiers are special in
+that they can only be enabled, not disabled, and the C<d>, C<l>, and
+C<u> modifiers are mutually exclusive: specifying one de-specifies the
others, and a maximum of one may appear in the construct. Thus, for
example, C<(?-p)>, C<(?-d:...)>, and C<(?dl:...)> will warn when
compiled under C<use warnings>.
--
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