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To: "Peter Stephenson" <pws@ibmth.df.unipi.it>, zsh-workers@sunsite.auc.dk
Subject: Re: PATCH: param stuff and was: PATCH: 3.1.5-pws-12: _brace_parameter 
In-Reply-To: ""Andrej Borsenkow""'s message of "Wed, 17 Mar 1999 17:35:30 NFT."
             <001201be7083$68588150$21c9ca95@mowp.siemens.ru> 
Date: Wed, 17 Mar 1999 15:52:01 +0100
From: Peter Stephenson <pws@ibmth.df.unipi.it>

"Andrej Borsenkow" wrote:
> >
> > It's actually completely predictable, once you know the rule.
> >

I wrote that rather primly before I discovered the difference between
"${foo[1]}" and "${${(@)foo}[1]}" where foo is an array, which made me
rather less keen on this as a transformational generative grammar :-)

> itsrm2% foo=(axb cxd)
> itsrm2% print -l ${(s/x/)foo}
> a
> b c
> d
> 
> itsrm2% foo=("a b" "c d")
> itsrm2% print -l ${=foo}
> a
> b
> c
> d

The rule is that, before splitting, all the words are joined together; by
default this happens with a space.  (At least some of this is in the
manual, not necessarily where you want for the present purpose.)  So in
both cases the string is first joined with a space (what Chomsky would call
a trace :-) sorry, I'm enjoying myself) and the `deep structure' is
"axb cxd", "a b c d" respectively; in the second it's then split on a
space, too.  Compare

% foo=(axb cxd)
% print -l ${(j/x/s/x/)foo
a
b
c
d

where the bit you don't see is now "axbxcxd".

> The second question is, what is applied first - flags or modifications?
> Again, after soms tests :-)
> 
> itsrm2% foo=(ax1 bx1)
> itsrm2% print -l ${(s/x/)foo%%1*}
> a
>  b

Yes, that's perhaps a bit unexpected and should be documented;
${${(s/x/)foo}%%1*} does what you might have expected.  

Now I tried:

% print -l "'"${(j/x/s/x/)^foo%%1*}"'" 
'a'
''
'b'
''

where the removal of the 1 seems to happen only after the splitting, so
I'm still a bit confused.

I'll look at the manual when I get a moment, but I'm trying to remember how
to minimize some functions of matrices.

> P.S. Please, don't take me too hard. But just try to pretend itself a ZSH
> newbie for a while ...

This is useful, because people keep complaining that they don't like the
documentation, and then fail to say what's wrong with it.  This way we
finally find out.

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy