zsh-workers
 help / color / mirror / code / Atom feed
From: Sebastian Gniazdowski <sgniazdowski@gmail.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: [PATCH] Support the mksh's ${|func;} substitution
Date: Tue, 10 Sep 2019 04:20:20 +0200	[thread overview]
Message-ID: <CAKc7PVCLpZ6_+bK8iQW0qPLB0t-iNcZmHV9WsWNGoCm_85QODA@mail.gmail.com> (raw)
In-Reply-To: <CAKc7PVB-V8Gqd2Pg8X=YjQDyPC=zG3keaKtdiS8cFCgfUOT_EA@mail.gmail.com>

I thought that I ask: should I continue working on the feature? I.e.
does it have a chance of being accepted?

The feature would be: a new substitution flag (x for execute, or | to
mark similarity to mksh's ${|code;}) that would execute the provided
code and substitute the value of $REPLY. E.g.:

- var='REPLY=test'; echo ${(x)var} -> test
- echo ${(x):-REPLY=test2} -> test2
- noglob print -rl ${(x):-for val (test test3) {
REPLY=\$val
}}
-> test3

The usefulness is the ability to map code onto array elements (with
(#m) or (#b) flags) and general lambda-like use-case.


On Sat, 7 Sep 2019 at 23:19, Sebastian Gniazdowski
<sgniazdowski@gmail.com> wrote:
>
> On Sat, 7 Sep 2019 at 22:19, Stephane Chazelas
> <stephane.chazelas@gmail.com> wrote:
> >
> > 2019-09-07 20:09:57 +0200, Sebastian Gniazdowski:
> > > The parsing would have to be changed to prevent the "=" in function names?
> > [...]
> >
> > No, I meant that you'd need the parser to handle that case of a
> > pseudo-command group  (a {any shell code here} but with {|
> > instead of {)).
> >
> > So you can do:
> >
> > echo ${|
> >   whatever $(...)
> >   for i do
> >     ...
> >   done}
> >
> > Whether it would actually be difficult or not I can't comment,
> > I've not looked at the parser code.
>
> I think that it's already supported with the single exception that }
> would have to be quoted:
>
> % print ${|
>   whatever $(...)
>   for i do
>     ...
>   done;}
> zsh: no such function: \n  whatever $(...)\n  for i do\n    ...\n  done
>
> > Having an operator that *only* invokes a function to do an
> > expansion is less useful IMO. That just sound like a very
> > limited form of command substitution where you could have done a
> > more complete form by allowing any code instead of just one
> > function invocation without argument.
>
> Ok, I agree, the lambda-function reminiscent version is better. It
> also isn't much harder to implement – instead of the doshfunc() just
> bin_eval() would have to be called. I attach such patch. However, it
> has some problems:
>
> arr=( val1 val2 abc1 abc3 )
> print ${arr[@]//(#b)(*)/${|REPLY\=test;}}
> Output:test test test test
>
> So the = has to be quoted. Also, not much more works. REPLY\=$MATCH
> nor REPLY\=\$MATCH are working. I wonder why, as it doesn't look that
> bad in general:
>
> whatever() { echo func ran; }
> echo ${|
>   whatever $(...)
>   for i in a b c; do
>     REPLY\=1
>   done;}
>
> Output:
> func ran
> 1
>
> --
> Sebastian Gniazdowski
> News: https://twitter.com/ZdharmaI
> IRC: https://kiwiirc.com/client/chat.freenode.net:+6697/#zplugin
> Blog: http://zdharma.org



--
Sebastian Gniazdowski
News: https://twitter.com/ZdharmaI
IRC: https://kiwiirc.com/client/chat.freenode.net:+6697/#zplugin
Blog: http://zdharma.org

  reply	other threads:[~2019-09-10  2:21 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06  0:52 Sebastian Gniazdowski
2019-09-06  0:54 ` Sebastian Gniazdowski
2019-09-06 23:16 ` Sebastian Gniazdowski
2019-09-07 12:16   ` Daniel Shahaf
2019-09-07 15:07 ` Stephane Chazelas
2019-09-07 18:09   ` Sebastian Gniazdowski
2019-09-07 20:19     ` Stephane Chazelas
2019-09-07 21:19       ` Sebastian Gniazdowski
2019-09-10  2:20         ` Sebastian Gniazdowski [this message]
2019-09-10  5:29           ` Bart Schaefer
2019-09-10 18:21             ` Sebastian Gniazdowski
2019-09-10 19:38               ` Bart Schaefer
2019-09-12  0:08                 ` Sebastian Gniazdowski
2019-09-12  1:03                   ` Bart Schaefer
2019-09-12  2:06                     ` Sebastian Gniazdowski
2019-09-12  5:35                       ` Bart Schaefer
2019-09-12  6:00                         ` Sebastian Gniazdowski
2019-09-12  6:55                           ` Bart Schaefer
2019-09-13 20:28                             ` Sebastian Gniazdowski
2019-09-13 21:33                               ` Bart Schaefer
2019-09-13 21:36                                 ` Bart Schaefer
2019-09-14  0:41                                   ` Sebastian Gniazdowski
2019-09-14  0:44                                     ` Sebastian Gniazdowski
2023-05-03 14:46 Sebastian Gniazdowski
2023-07-04  1:55 ` Bart Schaefer
2023-07-04 18:53   ` Lawrence Velázquez
2023-07-05  5:32     ` Bart Schaefer
2023-07-05  6:30       ` Bart Schaefer
2023-07-06  1:39       ` Bart Schaefer
2023-07-06  2:27         ` Mikael Magnusson
2023-07-06  4:00           ` Bart Schaefer
2023-07-18  3:14             ` Bart Schaefer

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAKc7PVCLpZ6_+bK8iQW0qPLB0t-iNcZmHV9WsWNGoCm_85QODA@mail.gmail.com \
    --to=sgniazdowski@gmail.com \
    --cc=zsh-workers@zsh.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.vuxu.org/mirror/zsh/

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).