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From: Martijn Dekker <martijn@inlv.demon.nl>
Newsgroups: comp.unix.shell
Subject: Re: [ksh93u+m] Interactive subshell expansion disfunctional
Date: Tue, 2 Jul 2024 04:35:28 +0100
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Op 22-06-2024 om 13:15 schreef Janis Papanagnou:
> On 22.06.2024 04:10, Janis Papanagnou wrote:
>> On 22.06.2024 01:14, Martijn Dekker wrote:
>>> Op 21-05-2024 om 17:57 schreef Janis Papanagnou:
>>>> I recently replaced all original ksh93u+ by ksh93u+m, and meanwhile
>>>> noticed quite some deficiencies, things that worked in original ksh
>>>> but not any more in ksh93u+m.
>>>
>>> I would of course be very interested in learning what deficiencies
>>> (other than the below) you've been observing.
>>
>> Unfortunately I haven't kept track. It's just that I noticed that
>> a couple things that worked before do not any more. Partly because
>> they were probably anyway only considered experimental, partly it
>> were features that I'd suspect are not commonly used.
>>
>> Off the top of my head one was the support of ksh's alarm timers,

The undocumented 'alarm' built-in was removed in 93u+m/1.0 because it was 
broken and could easily crash the shell; Korn kept it in for years but never 
fixed it. My standards are higher than that. I prefer not to ship stuff that I 
know is broken.

It is still present on the dev branch which will eventually become 93u+m/1.1, 
though. If we manage to fix it properly, then it will reappear in that 
release, but I can't promise it.

>> and another thing was in context of discipline functions used on
>> shell variables. (In the latter case I have no certainty whether
>> it's a shell issue or whether I should have done this differently.
> 
> An example for the above mentioned effect shows up like that...
> 
>    $ pushftp
>    pushftp: LINES.set: line 44: .kosta.rows=24: no parent
>    pushftp: COLUMNS.set: line 45: .kosta.cols=79: no parent
>    pushftp: line 11: 1: pushftp file ftp-path [ domain ]
[...]
> I can't tell whether I have missed something with discipline functs
> on built-in variables, how I used the namespaces, or something like
> that. (My tries to fix that in my program logic all failed.) Though
> the above "no parent" error messages did not show up with ksh93u+.

The fix for this is a prior 'typeset .kosta' (or even just '.kosta=') to 
create the parent variable.

To the best of my knowledge, this is exactly the same in 93u+ 2012-08-01:

$ /bin/ksh -c 'echo ${.sh.version}; .kosta.rows=24'
Version AJM 93u+ 2012-08-01
/bin/ksh: .kosta.rows=24: no parent
$ /bin/ksh -c 'typeset .kosta; .kosta.rows=24; echo ${.kosta.rows}'
24

-- 
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||    https://github.com/modernish/modernish
||
||    KornShell lives!
||    https://github.com/ksh93/ksh