ideas

ideas

[Quinn Dunkan]

Here are a few ideas for new zsh features.  It may be that it is already
possible to do these things with existing features, if so I'd love to know
how.

${...#...} and ${...%...} chop things off the begginning or ends of variables,
and I've wondered why there isn't something like ${i:s/foo/bar} to replace foo
in $i with bar.  With ${(S)...%...} one can chop things out of the center of a
variable, but what if you want to replace it with soething else?  Actually, it
would be even better if you could put in a regexp.  Regexps in the [[ ]]
construct would be nice too---"if echo $blah | grep -q; then..." is kind of
clumsy.  I've written some really ugly perl scripts that would have been much
nicer in shell, but weren't because no shell I know of has very powerful string
handling.

In HPUX, you can chase symlinks by sticking a / on the end of them, even if
they're not directories.  Example:

% touch a
% ln -s a b
% ls -F
a
b@
% rm b/
% ls
a
%

Other OSs don't do this, and even in zsh, something like:

% ls -l =latex
lrwxrwxrwx   1 root     tex             7 Aug 14  1997 /usr/local/lib/texmf/bin/latex -> latex2e
% ls -l =latex/
lrwxrwxrwx   1 root     tex             6 Aug 14  1997 /usr/local/lib/texmf/bin/latex2e -> virtex
% ls -l =latex//
-rwxr-xr-x   1 root     tex        198196 Dec  7  1996 /usr/local/lib/texmf/bin/virtex

won't work because zsh doesn't know about it, and you can't resolve them with
tab.  Even though it's an operating system feature, I see know reason why the
shell couldn't do it too.

Re: ideas

[Christopher Craig]

Included From: Quinn Dunkan <quinn@envy.ugcs.caltech.edu>: 

> and I've wondered why there isn't something like ${i:s/foo/bar} to
> replace foo in $i with bar.

You could just use $i(:s/foo/bar).  

--
Christopher A. Craig <ccraig@cc.gatech.edu>
"Efficiency is intelligent laziness" Arnold H. Glasow
PGP Key Verification: EE B1 F3 A0 3F BC 3C C7 81 61 F1 91 6E 99 13 65
http://www.cc.gatech.edu/people/home/ccraig

Re: ideas

[Bernd Eggink]

Christopher Craig wrote:
> 
> Included From: Quinn Dunkan <quinn@envy.ugcs.caltech.edu>:
> 
> > and I've wondered why there isn't something like ${i:s/foo/bar} to
> > replace foo in $i with bar.
> 
> You could just use $i(:s/foo/bar).

Great! I, too, was wondering why there isn't such a thing. Now I wonder
if this feature is considered top secret. I can't find anything about it
in the docu.

And, BTW, at least in zsh-3.1.2-zefram3, this doesn't work correctly. 

   print abcdefg(:s/b/XY)
   aXYecdefg

where the e following Y has two dots on it. But this works:

   print abcdefg(:s/b/XY/)
   aXYcdefg

- Bernd

-- 
Bernd Eggink
Regionales Rechenzentrum der Universitaet Hamburg
eggink@rrz.uni-hamburg.de
http://www.rrz.uni-hamburg.de/eggink/BEggink.html

Re: ideas

[Bart Schaefer]

On Mar 18, 12:03am, Quinn Dunkan wrote:
} Subject: ideas
}
} ${...#...} and ${...%...} chop things off the begginning or ends
} of variables, and I've wondered why there isn't something like
} ${i:s/foo/bar} to replace foo in $i with bar. With ${(S)...%...}
} one can chop things out of the center of a variable, but what if
} you want to replace it with soething else?

In addition to ${var}(:s/foo/bar/) [which BTW in 3.0.5 requires the
trailing / to work correctly, a bug] there's always

	${var%foo*}bar${var#*foo}

Or even

	r=(${(BE)=var%foo*})
	l=(${(BE)=var#*foo})
	${var[$l[1],$r[1]-1]}bar${$var[$l[2],$r[2]-1]}

In which case the removed portion is

	${var[$r[1],$l[2]-1]}

} Actually, it would be even better if you could put in a regexp.

How often is a glob pattern not sufficient?  With extendedglob, you
can write almost any regexp as a glob.  The big thing you lose is the
ability to substitute the matches for sub-patterns of the regexp into
the replacement.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com