[regex-coach] Please implement variable length look-behind functionality

[Edi Weitz]

Hi,

On Thu, Jun 25, 2009 at 2:17 PM, Alex Grässer<pyropunk51 at gmail.com> wrote:

> Thank you very much for Regex Coach. It has helped tremendously!

You're welcome... :)

> Recently I needed to use a negative look-behind with multiple exclusions and
> found that Regex Coach does not support variable length look-behind.
>
> \\[^\\]*(?<!(tmp|files))$
>
> gives an error that "Variable length look-behind not implemented (yet)"
>
> whereas
>
> \\[^\\]*(?<!(tmp|les))$
>
> works, except that it excludes more than required.
>
> Interestingly WinMerge also has this restriction ;-)

Most regex engines have this restriction.  In fact, I don't know any
offhand that don't.  (But I'm not an expert.)

Having said that, I don't have plans to implement variable-length
look-behind anytime soon.  Sorry if the "yet" part seems to imply
otherwise.

Cheers,
Edi.