unless (($key =~ /^,|,,|,$/))

Cute, testing for the negative is much more readable here ... but probably something I wouldn't have tried. You need to check for the characters being in the valid class though (and I'd also put brackets around the anchors) so that would make it... 

 unless (($key =~ /(?:^,)|,,|[^a-zA-Z,]|(?:,$)))

[download]

Which isn't quite as nice anymore :(. So I'd probably still use the "obvious" non-negative... 

 if (($key =~ /^[a-zA-Z]+(?:,[a-zA-Z]+)*$))

[download]

Or if I was feeling really special, I might even do... 

 my $field = qr([a-zA-Z]+);
 if (($key =~ /^$field(?:,$field)*$))

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...which is slightly more readable IMO.

update (broquaint): changed <pre> to <code> tags

In reply to Re: Re: regex: only want [a-zA-Z] and comma chars in a string by nevyn
in thread regex: only want [a-zA-Z] and comma chars in a string by heezy

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