If I understand what he is doing correctly, he is only playing games with deciding whether or not to capture. If you capture, the decision of whether or not to capture $` and $' is separate.

I would like the pragma to be able to decide not just whether or not to capture, but whether or not to copy the whole string. $`/$' are already distinguished from $& in Perl, and separate control would be nice here.

UPDATE
As just discussed in chatter. Using $& is documented in perlre (as of 5.005 and later) as not being as bad as $` and $'. But in my simple test above, it produced the same slowdown. Which indicates a mistake in the documentation...

Ok. I think there is a bug with the current Perl right now:

#!/usr/bin/perl -l

$_ = "japhy";
1 while /(.)/g;
$_ = "upset";
print $1;  # does this print 'y' or 't' for you?
[download]

That code prints "t" for my bleadperl. This means that Perl is not copying the string it matches, but just using a pointer to the string. That explains why this code runs JUST AS FAST as

#!/usr/bin/perl -l

$_ = "japhy";
1 while /./g;
$_ = "upset";
[download]

Now, this makes the test tilly wrote null and void.

_____________________________________________________
Jeff[japhy]Pinyan: Perl, regex, and perl hacker.
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;