Make the UTF-8 decoding stricter and more verbose when

[p5sagit/p5-mst-13.2.git] / pod / perlre.pod

diff --git a/pod/perlre.pod b/pod/perlre.pod
index 2db4139..380bc5f 100644 (file)
--- a/pod/perlre.pod
+++ b/pod/perlre.pod
@@ -169,7 +169,7 @@ You'll need to write something like C<m/\Quser\E\@\Qhost/>.
 In addition, Perl defines the following:
 
     \w Match a "word" character (alphanumeric plus "_")
-    \W Match a non-word character
+    \W Match a non-"word" character
     \s Match a whitespace character
     \S Match a non-whitespace character
     \d Match a digit character
@@ -180,7 +180,7 @@ In addition, Perl defines the following:
         equivalent to C<(?:\PM\pM*)>
     \C Match a single C char (octet) even under utf8.
 
-A C<\w> matches a single alphanumeric character, not a whole word.
+A C<\w> matches a single alphanumeric character or C<_>, not a whole word.
 Use C<\w+> to match a string of Perl-identifier characters (which isn't 
 the same as matching an English word).  If C<use locale> is in effect, the
 list of alphabetic characters generated by C<\w> is taken from the
@@ -199,24 +199,30 @@ equivalents (if available) are as follows:
     alpha
     alnum
     ascii
+    blank              [1]
     cntrl
     digit       \d
     graph
     lower
     print
     punct
-    space       \s
+    space       \s     [2]
     upper
-    word        \w
+    word        \w     [3]
     xdigit
 
+  [1] A GNU extension equivalent to C<[ \t]>, `all horizontal whitespace'.
+  [2] Not I<exactly equivalent> to C<\s> since the C<[[:space:]]> includes
+      also the (very rare) `vertical tabulator', "\ck", chr(11).
+  [3] A Perl extension. 
+
 For example use C<[:upper:]> to match all the uppercase characters.
-Note that the C<[]> are part of the C<[::]> construct, not part of the whole
-character class.  For example:
+Note that the C<[]> are part of the C<[::]> construct, not part of the
+whole character class.  For example:
 
     [01[:alpha:]%]
 
-matches one, zero, any alphabetic character, and the percentage sign.
+matches zero, one, any alphabetic character, and the percentage sign.
 
 If the C<utf8> pragma is used, the following equivalences to Unicode
 \p{} constructs hold:
@@ -224,6 +230,7 @@ If the C<utf8> pragma is used, the following equivalences to Unicode
     alpha       IsAlpha
     alnum       IsAlnum
     ascii       IsASCII
+    blank      IsSpace
     cntrl       IsCntrl
     digit       IsDigit
     graph       IsGraph
@@ -238,8 +245,8 @@ If the C<utf8> pragma is used, the following equivalences to Unicode
 For example C<[:lower:]> and C<\p{IsLower}> are equivalent.
 
 If the C<utf8> pragma is not used but the C<locale> pragma is, the
-classes correlate with the isalpha(3) interface (except for `word',
-which is a Perl extension, mirroring C<\w>).
+classes correlate with the usual isalpha(3) interface (except for
+`word' and `blank').
 
 The assumedly non-obviously named classes are:
 
@@ -250,23 +257,24 @@ The assumedly non-obviously named classes are:
 Any control character.  Usually characters that don't produce output as
 such but instead control the terminal somehow: for example newline and
 backspace are control characters.  All characters with ord() less than
-32 are most often classified as control characters.
+32 are most often classified as control characters (assuming ASCII,
+the ISO Latin character sets, and Unicode).
 
 =item graph
 
-Any alphanumeric or punctuation character.
+Any alphanumeric or punctuation (special) character.
 
 =item print
 
-Any alphanumeric or punctuation character or space.
+Any alphanumeric or punctuation (special) character or space.
 
 =item punct
 
-Any punctuation character.
+Any punctuation (special) character.
 
 =item xdigit
 
-Any hexadecimal digit.  Though this may feel silly (/0-9a-f/i would
+Any hexadecimal digit.  Though this may feel silly ([0-9A-Fa-f] would
 work just fine) it is included for completeness.
 
 =back
@@ -352,7 +360,7 @@ everything before the matched string.  And C<$'> returns everything
 after the matched string.
 
 The numbered variables ($1, $2, $3, etc.) and the related punctuation
-set (C<<$+>, C<$&>, C<$`>, and C<$'>) are all dynamically scoped
+set (C<$+>, C<$&>, C<$`>, and C<$'>) are all dynamically scoped
 until the end of the enclosing block or until the next successful
 match, whichever comes first.  (See L<perlsyn/"Compound Statements">.)
 
@@ -377,10 +385,11 @@ that looks like \\, \(, \), \<, \>, \{, or \} is always
 interpreted as a literal character, not a metacharacter.  This was
 once used in a common idiom to disable or quote the special meanings
 of regular expression metacharacters in a string that you want to
-use for a pattern. Simply quote all non-alphanumeric characters:
+use for a pattern. Simply quote all non-"word" characters:
 
     $pattern =~ s/(\W)/\\$1/g;
 
+(If C<use locale> is set, then this depends on the current locale.)
 Today it is more common to use the quotemeta() function or the C<\Q>
 metaquoting escape sequence to disable all metacharacters' special
 meanings like this: