From: Stephane Chazelas <stephane.chazelas@gmail.com>
To: Peter Stephenson <p.stephenson@samsung.com>
Cc: Zsh hackers list <zsh-users@zsh.org>
Subject: Re: ${^var} and word splitting
Date: Mon, 24 Nov 2014 15:26:28 +0000 [thread overview]
Message-ID: <20141124152628.GA5749@chaz.gmail.com> (raw)
In-Reply-To: <20141124111201.161d8cf2__23261.8202259347$1416827641$gmane$org@pwslap01u.europe.root.pri>
2014-11-24 11:12:01 +0000, Peter Stephenson:
> On Mon, 24 Nov 2014 09:56:37 +0000
> Stephane Chazelas <stephane.chazelas@gmail.com> wrote:
> > $ a=' 1 2 3 '
> > $ print -l $=a
> > 1
> > 2
> > 3
> > $ print -l x$^=a
> > x
> > x1
> > x2
> > x3
> > x
> > $ print -l x${^${=a}}
> > x1
> > x2
> > x3
> >
> >
> > Why the extra "x" lines with x$^=a ?
>
> In the case of $^=a, the steps are
>
> - split a. There's whitespace start and end so you get null elements
> corresponding to those.
> - add the x's in front
> - remove remaining null elements, but there aren't any.
OK thanks. that's a difference from other shells I was not aware
of and it seems to be as documented indeed.
The source of my confusion can be simplified to:
~$ a=' 1 2 3 '
~$ printf '%s\n' "${=a}"
1
2
3
~$
In other shells, leading/trailing _IFS white space_ characters
are ignored as part of word splitting, not in zsh.
If I understand correctly, in zsh the removing of those are
accounted to null-removal in things like:
$ print -l $=a
1
2
3
But then it's not clear why they are removed there and not in:
a=':a::b:'
IFS=:
print -l $=a
?
--
Stephane
next prev parent reply other threads:[~2014-11-24 15:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-24 9:56 Stephane Chazelas
2014-11-24 11:12 ` Peter Stephenson
[not found] ` <20141124111201.161d8cf2__23261.8202259347$1416827641$gmane$org@pwslap01u.europe.root.pri>
2014-11-24 15:26 ` Stephane Chazelas [this message]
2014-11-24 15:55 ` Peter Stephenson
2014-11-24 16:55 ` Bart Schaefer
2014-11-24 17:22 ` Peter Stephenson
[not found] ` <20141124155524.0739b3ec__26419.4987401881$1416845250$gmane$org@pwslap01u.europe.root.pri>
2014-11-24 21:18 ` Stephane Chazelas
2014-11-25 7:49 ` Bart Schaefer
[not found] ` <141124234931.ZM17259__8246.8130779036$1416901919$gmane$org@torch.brasslantern.com>
2014-11-25 12:12 ` Stephane Chazelas
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