Re: ${^MATCH} sometimes fails in target of substitution?

perlre states:

As a workaround for this problem, Perl 5.10.0 introduces ${^PREMATCH} , ${^MATCH} and ${^POSTMATCH} , which are equivalent to $` , $& and $' , except that they are only guaranteed to be defined after a successful match that was executed with the /p (preserve) modifier.

Update: The problem you have documented is a bug in releases prior to 5.18.See Re: ${^MATCH} sometimes fails in target of substitution?.

Before 5.18 it appears that ${^MATCH} may only be available AFTER the match/replace. Adding print $(^MATCH} to your both example prints 'bcd' e.g.

 perl -e '$x = "abcde";             $x =~ s/b../==${^MATCH}==/p;  prin
+t "$x Match:${^MATCH}\n"'
a====e Match:bcd
perl -e '$x = "abcde"; $sub="b.."; $x =~ s/$sub/==${^MATCH}==/p; print
+ "$x Match:${^MATCH}\n"'
a==bcd==e Match:bcd
[download]

If you spot any bugs in my solutions, it's because I've deliberately left them in as an exercise for the reader! :-)

Comment on Re: ${^MATCH} sometimes fails in target of substitution? Download Code

Replies are listed 'Best First'.
Re^2: ${^MATCH} sometimes fails in target of substitution? by ikegami (Patriarch) on Jun 17, 2013 at 08:16 UTC
If you're replacing, there was a successful match. This is a bug. Testing reveals this bug has been fixed: `$ perl -v \| grep 'This is' This is perl 5, version 16, subversion 3 (v5.16.3) built for x86_64-li +nux-thread-multi $ perl -E'$_ = "abcde"; s/b../==${^MATCH}==/p; say' a====e $ perl -E'$_ = "abcde"; $sub="b.."; s/$sub/==${^MATCH}==/p; say' a==bcd==e` [download] `$ perl -v \| grep 'This is' This is perl 5, version 18, subversion 0 (v5.18.0) built for x86_64-li +nux-thread-multi $ perl -E'$_ = "abcde"; s/b../==${^MATCH}==/p; say' a==bcd==e $ perl -E'$_ = "abcde"; $sub="b.."; s/$sub/==${^MATCH}==/p; say' a==bcd==e` [download]	[reply] [d/l] [select]
Re^3: ${^MATCH} sometimes fails in target of substitution? by space_monk (Chaplain) on Jun 17, 2013 at 10:11 UTC
Thanks, I amended my answer to reflect your comment and the earlier one of dave_the_m. If you spot any bugs in my solutions, it's because I've deliberately left them in as an exercise for the reader! :-)	[reply]


Syntactic Confectionery Delight
	PerlMonks