X<\g{1}> X<\g{-1}> X<\g{name}> X<relative backreference> X<named backreference>
In order to provide a safer and easier way to construct patterns using
-backreferences, Perl 5.10 provides the C<\g{N}> notation. The curly
-brackets are optional, however omitting them is less safe as the meaning
-of the pattern can be changed by text (such as digits) following it.
-When N is a positive integer the C<\g{N}> notation is exactly equivalent
-to using normal backreferences. When N is a negative integer then it is
-a relative backreference referring to the previous N'th capturing group.
-When the bracket form is used and N is not an integer, it is treated as a
-reference to a named buffer.
+backreferences, Perl provides the C<\g{N}> notation (starting with perl
+5.10.0). The curly brackets are optional, however omitting them is less
+safe as the meaning of the pattern can be changed by text (such as digits)
+following it. When N is a positive integer the C<\g{N}> notation is
+exactly equivalent to using normal backreferences. When N is a negative
+integer then it is a relative backreference referring to the previous N'th
+capturing group. When the bracket form is used and N is not an integer, it
+is treated as a reference to a named buffer.
Thus C<\g{-1}> refers to the last buffer, C<\g{-2}> refers to the
buffer before that. For example:
and would match the same as C</(Y) ( (X) \3 \1 )/x>.
-Additionally, as of Perl 5.10 you may use named capture buffers and named
+Additionally, as of Perl 5.10.0 you may use named capture buffers and named
backreferences. The notation is C<< (?<name>...) >> to declare and C<< \k<name> >>
to reference. You may also use apostrophes instead of angle brackets to delimit the
name; and you may use the bracketed C<< \g{name} >> backreference syntax.
other two.
X<$&> X<$`> X<$'>
-As a workaround for this problem, Perl 5.10 introduces C<${^PREMATCH}>,
+As a workaround for this problem, Perl 5.10.0 introduces C<${^PREMATCH}>,
C<${^MATCH}> and C<${^POSTMATCH}>, which are equivalent to C<$`>, C<$&>
and C<$'>, B<except> that they are only guaranteed to be defined after a
successful match that was executed with the C</p> (preserve) modifier.
This is the "branch reset" pattern, which has the special property
that the capture buffers are numbered from the same starting point
-in each alternation branch. It is available starting from perl 5.10.
+in each alternation branch. It is available starting from perl 5.10.0.
Capture buffers are numbered from left to right, but inside this
construct the numbering is restarted for each branch.
=head1 PCRE/Python Support
-As of Perl 5.10 Perl supports several Python/PCRE specific extensions
+As of Perl 5.10.0, Perl supports several Python/PCRE specific extensions
to the regex syntax. While Perl programmers are encouraged to use the
-Perl specific syntax, the following are legal in Perl 5.10:
+Perl specific syntax, the following are also accepted:
=over 4
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