in reply to Re: Re: Interpolation in character class
in thread Interpolation in character class

That'll teach me to blab about features I don't know without testing them first. Yes, positive lookahead would definitely be possible. You'd have to flip your test, though. 
$x = 'aba';
 
print $x =~ /(.)(?=\1)/
        ? "double!\n"
        : "not double!\n";
 
$x = 'abba';
print $x =~ /(.)(?=\1)/
        ? "double!\n"
        : "not double!\n";
----
not double!
double!

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The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

In Section Seekers of Perl Wisdom