From: Richard Hansen <rhansen@bbn.com>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: zsh-workers@zsh.org
Subject: Re: 'emulate sh -c' and $0
Date: Tue, 03 Jun 2014 19:35:51 -0400 [thread overview]
Message-ID: <538E5BD7.3070005@bbn.com> (raw)
In-Reply-To: <CAH+w=7Y79B25=m2qajTGi-xgZkZLMfvDyz3spnkz=MCXowDKNA@mail.gmail.com>
On 2014-06-03 17:10, Bart Schaefer wrote:
> On Jun 3, 2014 1:27 PM, "Peter Stephenson" <p.w.stephenson@ntlworld.com>
> wrote:
>> On Tue, 03 Jun 2014 16:15:25 -0400
>> Richard Hansen <rhansen@bbn.com> wrote:
>>> Although it would be a behavior change, I think it would be best if both
>>> 'emulate sh' and 'emulate sh -c' set POSIX_ARGZERO by default
>>
>> Yes, that's the policy --- backward compatibility is for native mode, sh
>> compatibility can be improved without worrying about that.
>
> The complexity here is that we're not just dealing with a particular
> emulation, we're dealing with switching from one emulation to another (and
> possibly back again) in the middle of a running shell session, and the
> effect that has on a dynamically scoped variable that crosses the emulation
> boundaries.
Isn't this a general problem with how zsh supports mix-and-match shell
code? Here's a contrived example:
echo_stuff() { printf %s\\n "$*"; }
foo() { ${CMD} words here; }
CMD=echo_stuff
IFS=_
printf "outside sh emulation: "; foo
printf "inside sh emulation: "; emulate sh -c foo
As stated in detail #2 in the documentation for the emulate builtin,
options aren't restored when calling foo from sh emulation mode. That
causes the above script to produce the following output:
outside sh emulation: words_here
inside sh emulation: stuff words here
Because foo was defined outside of emulate I would have expected zsh to
treat the body of foo as native zsh code regardless of the emulation
mode of the calling code. If I hadn't read the detailed emulate rules
and didn't understand how emulate worked with regard to options, I would
have expected the following output:
outside sh emulation: words_here
inside sh emulation: words_here
(same output for the same function in the same script)
To get the behavior I expect, I have to do the following:
define_functions() {
echo_stuff() { printf %s\\n "$*"; }
foo() { ${CMD} words here; }
}
emulate zsh -c define_functions
CMD=echo_stuff
IFS=_
printf "outside sh emulation: "; foo
printf "inside sh emulation: "; emulate sh -c foo
If zsh restored options when a non-sticky function is called from within
emulation then I wouldn't have to do the above define_functions hack.
(And $0 would act like I expect assuming POSIX_ARGZERO is enabled in sh
emulation mode.)
-Richard
next prev parent reply other threads:[~2014-06-03 23:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-29 23:04 Richard Hansen
2014-05-30 3:45 ` Bart Schaefer
2014-05-30 8:49 ` Richard Hansen
2014-05-30 17:00 ` Bart Schaefer
2014-05-30 21:14 ` Richard Hansen
2014-05-31 5:13 ` Bart Schaefer
2014-05-31 23:47 ` Bart Schaefer
2014-06-03 20:15 ` Richard Hansen
2014-06-03 20:26 ` Peter Stephenson
2014-06-03 21:10 ` Bart Schaefer
2014-06-03 23:35 ` Richard Hansen [this message]
2014-06-04 0:09 ` Bart Schaefer
2014-06-03 21:21 ` Bart Schaefer
2014-06-03 22:54 ` Richard Hansen
2014-06-04 0:03 ` Bart Schaefer
2014-06-04 1:10 ` Bart Schaefer
2014-06-04 1:23 ` Bart Schaefer
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