Re: RFC 72 (v2) The regexp engine should go backward as well as forward.

mike mulligan writes:
:If it important to be able to do both:
:
:  $large = join '|', @possible'
:  $data =~ / (?<= $large) GAAC /x;   # Don't care which @possible?
:
:and
:
:  $data =~ m/ ($large) GAAC /x;   # Need $1 to say which @possible
:
:Then perhaps a back-reference-setting look-behind could be implemented?
:Don't have an obvious syntax to use (back-tick == back-reference?), but
:something like:
:
:  $data =~ m/ (?`<= $large) GAAC /x;   # Need $1 to say which @possible
:
:Does this ehanced look-behind satisfy the RFC's needs?

Note that you can already get backreferences out of zero-width
assertions. Like the Tardis, it only looks zero-width from the
outside:

  "test" =~ /(?<=(t))(.)/ and print $1, $2;

Hugo