Re: [Exim] Grouping allowed in system filter pcre?

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Author: Sheldon Hearn
Date:  
To: exim-users
Subject: Re: [Exim] Grouping allowed in system filter pcre?
On (2002/08/16 14:50), Philip Hazel wrote:

> \N is not a regex-ism. It's a feature of Exim 4 string expansion that
> says "don't expand stuff between \Ns". Thus, it is highly useful for
> wrapping regexs.


Ah, I'll have a look at the docs.

> >    if $recipients is '$recipients'

> >
> > But I don't think that's a strong case for excluding it from the Wish
> > List. :-)
>
> Hmm. That example is, sadly, a good case NOT to do it with that syntax.
>
> What? Have I gone mad? I hope not:


I think perhaps just a little. :-)

> What I was suggesting was non-*escaping* quotes, not non-*interpolating*
> quotes, as a way of not escaping \ in strings. If I were to use ' as
> suggested, there would be no difference between '$recipients' and
> "$recipients" because neither string contains a backslash.


That's only because...

> Exim's string expansion (which recognizes dollars) happens later. [And
> actually, $recipients is a bad example, because is isn't really a
> variable.]


Non-interpolating quotes would also be non-expanding (since Exim's
expanding is a superset of variable interpolation).

> I fear that if I use ' for this, it will confuse Perl and Shell users.


Given how we've already confused each other on this topic, I'd agree
with you there. :-)

> I need to think of some other syntax. However, doing *anything* might
> break existing configurations and filters, so I'm exceedingly cautious.
> This really only matters for regular expressions, and the users of those
> are generally "sophisticated"... :-)


I think many of your users would prefer you to be exceedingly cautious
than to haphazardly break their hitherto working configurations. :-)

Ciao,
Sheldon.