What are you talking about cheesyjames? I can guess, and it'd be a pretty good guess at that, but I do not want to. You must tell me what you mean cheesyjames.

#!/usr/bin/perl -lw
use strict;
# here is one thing you might want
sub what
{
  my $what = shift;
  return ($what - 5);
}
my $string = 'a and a b and a 5 and a 6 and a 8 an what?';
print $string;
$string =~ s/(\d)/&what($1)/ge;
[download]

The other thing I think you might be thinking (dang that sounds stupid) is something along the lines of m/\d$pattern\b\l\a\h &what('what')/ where you want &what('what') to be expanded, in which case the only thing I can think of is for you to either store the value of &what in a variable.

update: well you could always use eval, but I find that is in poor taste (I think it is a piss poor choice in design, when one must resort to "passing" functions via STDIN).

 
___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"