minor bug in dumping blessed subrefs

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

diff --git a/pod/perlvar.pod b/pod/perlvar.pod
index 38fd168..b9b0ce6 100644 (file)
--- a/pod/perlvar.pod
+++ b/pod/perlvar.pod
@@ -17,6 +17,15 @@ at the top of your program.  This will alias all the short names to the
 long names in the current package.  Some even have medium names,
 generally borrowed from B<awk>.
 
+Due to an unfortunate accident of Perl's implementation, "C<use English>"
+imposes a considerable performance penalty on all regular expression
+matches in a program, regardless of whether they occur in the scope of
+"C<use English>".  For that reason, saying "C<use English>" in
+libraries is strongly discouraged.  See the Devel::SawAmpersand module
+documentation from CPAN
+(http://www.perl.com/CPAN/modules/by-module/Devel/Devel-SawAmpersand-0.10.readme)
+for more information.
+
 To go a step further, those variables that depend on the currently
 selected filehandle may instead (and preferably) be set by calling an
 object method on the FileHandle object.  (Summary lines below for this
@@ -127,6 +136,10 @@ The string matched by the last successful pattern match (not counting
 any matches hidden within a BLOCK or eval() enclosed by the current
 BLOCK).  (Mnemonic: like & in some editors.)  This variable is read-only.
 
+The use of this variable anywhere in a program imposes a considerable
+performance penalty on all regular expression matches.  See the
+Devel::SawAmpersand module from CPAN for more information.
+
 =item $PREMATCH
 
 =item $`
@@ -136,6 +149,10 @@ pattern match (not counting any matches hidden within a BLOCK or eval
 enclosed by the current BLOCK).  (Mnemonic: C<`> often precedes a quoted
 string.)  This variable is read-only.
 
+The use of this variable anywhere in a program imposes a considerable
+performance penalty on all regular expression matches.  See the
+Devel::SawAmpersand module from CPAN for more information.
+
 =item $POSTMATCH
 
 =item $'
@@ -151,6 +168,10 @@ string.)  Example:
 
 This variable is read-only.
 
+The use of this variable anywhere in a program imposes a considerable
+performance penalty on all regular expression matches.  See the
+Devel::SawAmpersand module from CPAN for more information.
+
 =item $LAST_PAREN_MATCH
 
 =item $+
@@ -168,13 +189,14 @@ This variable is read-only.
 
 $+[0] is the offset of the end of the last successfull match.
 C<$+[>I<n>C<]> is the offset of the end of the substring matched by
-I<n>-th subpattern.  
+I<n>-th subpattern, or undef if the subpattern did not match.
 
 Thus after a match against $_, $& coincides with C<substr $_, $-[0],
-$+[0]>.  Similarly, C<$>I<n> coincides with C<substr $_, $-[>I<n>C<],
-$+[>I<0>C<]> if C<$-[>I<n>C<]> is defined, and $+ conincides with
-C<substr $_, $-[-1], $+[-1]>.  One can use C<$#+> to find the last
-matched subgroup in the last successful match.  Compare with L<"@-">.
+$+[0] - $-[0]>.  Similarly, C<$>I<n> coincides with C<substr $_, $-[>I<n>C<],
+$+[>I<n>C<] - $-[>I<n>C<]> if C<$-[>I<n>C<]> is defined, and $+ coincides with
+C<substr $_, $-[$#-], $+[$#-]>.  One can use C<$#+> to find the number
+of subgroups in the last successful match.  Note the difference with
+C<$#->, which is the last I<matched> subgroup.  Compare with L<"@-">.
 
 =item $MULTILINE_MATCHING
 
@@ -389,13 +411,15 @@ channel.  (Mnemonic: lines_on_page - lines_printed.)
 
 $-[0] is the offset of the start of the last successfull match.
 C<$-[>I<n>C<]> is the offset of the start of the substring matched by
-I<n>-th subpattern.  
+I<n>-th subpattern, or undef if the subpattern did not match.
 
 Thus after a match against $_, $& coincides with C<substr $_, $-[0],
-$+[0]>.  Similarly, C<$>I<n> coincides with C<substr $_, $-[>I<n>C<],
-$+[>I<0>C<]> if C<$-[>I<n>C<]> is defined, and $+ conincides with
-C<substr $_, $-[-1], $+[-1]>.  One can use C<$#-> to find the last
-matched subgroup in the last successful match.  Compare with L<"@+">.
+$+[0] - $-[0]>.  Similarly, C<$>I<n> coincides with C<substr $_, $-[>I<n>C<],
+$+[>I<n>C<] - $-[>I<n>C<]> if C<$-[>I<n>C<]> is defined, and $+ coincides with
+C<substr $_, $-[$#-], $+[$#-]>.  One can use C<$#-> to find the last
+matched subgroup in the last successful match.  Note the difference with
+C<$#+>, which is the number of subgroups in the regular expression.  Compare
+with L<"@+">.
 
 =item format_name HANDLE EXPR
 
@@ -650,6 +674,15 @@ of perl in the right bracket?)  Example:
 See also the documentation of C<use VERSION> and C<require VERSION>
 for a convenient way to fail if the Perl interpreter is too old.
 
+=item $COMPILING
+
+=item $^C
+
+The current value of the flag associated with the B<-c> switch. Mainly
+of use with B<-MO=...> to allow code to alter its behaviour when being compiled.
+(For example to automatically AUTOLOADing at compile time rather than normal
+deferred loading.)  Setting C<$^C = 1> is similar to calling C<B::minus_c>.
+
 =item $DEBUGGING
 
 =item $^D
@@ -812,12 +845,16 @@ specified, and the value is the location of the file actually found.
 The C<require> command uses this array to determine whether a given file
 has already been included.
 
-=item %ENV  $ENV{expr}
+=item %ENV
+
+=item $ENV{expr}
 
 The hash %ENV contains your current environment.  Setting a
 value in C<ENV> changes the environment for child processes.
 
-=item %SIG  $SIG{expr}
+=item %SIG
+
+=item $SIG{expr}
 
 The hash %SIG is used to set signal handlers for various
 signals.  Example: