no-fork expansion with array var

no-fork expansion with array var

[Mikael Magnusson]

The documentation says:
  If param names an array, array expansion rules apply.

But what it means is if you do an array assignment to var inside the
code block, array expansion rules apply:
% typeset -a foo; print -rl - ${${|foo| foo=hi}[1]}
h
% typeset +a foo; print -rl - ${${|foo| foo=(hi)}[1]}
hi

I know that REPLY is special cased, but I also found this confusing:
% print -rl - ${|REPLY| REPLY=(hi there)} ${|REPLYY| REPLYY=(hi there)}
hi there
hi
there

restoring REPLY around the expansion shouldn't affect whether it was
returned as an array from inside the block, should it? Or we should at
least document that the special name REPLY is always expanded as a
scalar, whether it's named or used as the default name via
${|REPLY=(foo bar)}.

-- 
Mikael Magnusson

Re: no-fork expansion with array var

[Bart Schaefer]

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On Fri, Sep 22, 2023, 4:00 PM Mikael Magnusson <mikachu@gmail.com> wrote:

> The documentation says:
>   If param names an array, array expansion rules apply.
>
> But what it means is if you do an array assignment to var inside the
> code block, array expansion rules apply
>

There are two cases:  The parameter has already been declared an array, or
it's made an array by assignment within the expression.  I was trying to
cover both, but rephrasing welcome.

Or we should at
> least document that the special name REPLY is always expanded as a
> scalar


Oops, I thought I'd mentioned that.  It was certainly implied by the
descriptions of mksh behavior.  Anyway that is how it works.

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Re: no-fork expansion with array var

[Bart Schaefer]

On Fri, Sep 22, 2023 at 4:16 PM Bart Schaefer <schaefer@brasslantern.com> wrote:
>
> On Fri, Sep 22, 2023, 4:00 PM Mikael Magnusson <mikachu@gmail.com> wrote:
>>
>> The documentation says:
>>   If param names an array, array expansion rules apply.
>>
>> But what it means is if you do an array assignment to var inside the
>> code block, array expansion rules apply

How about this?

diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo
index 86a5f70c8..837a85db6 100644
--- a/Doc/Zsh/expn.yo
+++ b/Doc/Zsh/expn.yo
@@ -1915,8 +1915,9 @@ Substitutions of the form
`tt(${|)var(param)tt(|)...tt(})' are similar,
 except that the substitution is replaced by the value of the parameter
 named by var(param).  No implicit save or restore applies to var(param)
 except as noted for tt(REPLY), and var(param) should em(not) be declared
-within the command.  If var(param) names an array, array expansion rules
-apply.
+within the command.  If, after evaluating the expression, var(param)
+names an array, array expansion rules apply.  However, tt(REPLY) is
+always expanded in scalar context, even if assigned an array.

 A command enclosed in braces preceded by a dollar sign, and set off from
 the braces by whitespace, like `tt(${ )...tt( })', is replaced by its

Re: no-fork expansion with array var

[Mikael Magnusson]

On 9/23/23, Bart Schaefer <schaefer@brasslantern.com> wrote:
> On Fri, Sep 22, 2023 at 4:16 PM Bart Schaefer <schaefer@brasslantern.com>
> wrote:
>>
>> On Fri, Sep 22, 2023, 4:00 PM Mikael Magnusson <mikachu@gmail.com> wrote:
>>>
>>> The documentation says:
>>>   If param names an array, array expansion rules apply.
>>>
>>> But what it means is if you do an array assignment to var inside the
>>> code block, array expansion rules apply
>
> How about this?
>
> diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo
> index 86a5f70c8..837a85db6 100644
> --- a/Doc/Zsh/expn.yo
> +++ b/Doc/Zsh/expn.yo
> @@ -1915,8 +1915,9 @@ Substitutions of the form
> `tt(${|)var(param)tt(|)...tt(})' are similar,
>  except that the substitution is replaced by the value of the parameter
>  named by var(param).  No implicit save or restore applies to var(param)
>  except as noted for tt(REPLY), and var(param) should em(not) be declared
> -within the command.  If var(param) names an array, array expansion rules
> -apply.
> +within the command.  If, after evaluating the expression, var(param)
> +names an array, array expansion rules apply.  However, tt(REPLY) is
> +always expanded in scalar context, even if assigned an array.
>
>  A command enclosed in braces preceded by a dollar sign, and set off from
>  the braces by whitespace, like `tt(${ )...tt( })', is replaced by its

That works for me.

-- 
Mikael Magnusson