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Re: TPR1 post-mortem

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From:
Adam Spiers
Date:
March 8, 2002 08:27
Subject:
Re: TPR1 post-mortem
Message ID:
20020308162753.A16670@corelli.new.ox.ac.uk
Philippe 'BooK' Bruhat (philippe.bruhat@free.fr) wrote:
> What you want is:
> 
>     s/(?!^).(?!$)/$&$&/g
> 
> Now, can we shorten it?
> 
>     s/\B.(?=\B)/$&$&/g

Except that that tickles the bug discussed elsewhere in this thread,
and is hence no use.

$ echo 1234 | perl5.6.1 -lpe 's/\B.(?=\B)/$&$&/g'
12234

> Anything better?

Yep :-)

      s/(?=.(.).)/$+/g

Produces all but the penultimate pair in reverse order, which is of
course OK, because the function is symmetrical.  I didn't end up using
it though, and noone else did either, it seems.

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