glob inside nested parameter expansion returns glob string

glob inside nested parameter expansion returns glob string

[Jim]

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Hi,

The following two statements produce the expected results:

% A=(${:-.z*(.N)})
% A=(${A:#*(comp|hist)*})

When trying to nest the two, the result is the glob statement:

A=(${${:-.z*(.N)}:#*(comp|hist)*})

Trying to understand why this is the case.  Could someone explain why this
happens?
Is there a way to nest the two?

Thanks for your help,

Jim Murphy

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Re: glob inside nested parameter expansion returns glob string

[Mikael Magnusson]

On 4/21/22, Jim <linux.tech.guy@gmail.com> wrote:
> Hi,
>
> The following two statements produce the expected results:
>
> % A=(${:-.z*(.N)})
> % A=(${A:#*(comp|hist)*})
>
> When trying to nest the two, the result is the glob statement:
>
> A=(${${:-.z*(.N)}:#*(comp|hist)*})
>
> Trying to understand why this is the case.  Could someone explain why this
> happens?
> Is there a way to nest the two?

There is a certain order that parameter expansions and globs happen
relative to eachother, nesting param expansions does not change the
order of processing. Eg, there is not really any way you can process
.z* before the outer :# happens, which will operate on the
pre-expanded string in your final combined statement. In short, no(t
as far as I know).

-- 
Mikael Magnusson

Re: glob inside nested parameter expansion returns glob string

[Bart Schaefer]

On Thu, Apr 21, 2022 at 11:51 AM Mikael Magnusson <mikachu@gmail.com> wrote:
>
> On 4/21/22, Jim <linux.tech.guy@gmail.com> wrote:
> >
> > % A=(${:-.z*(.N)})
> > % A=(${A:#*(comp|hist)*})
> >
> > Is there a way to nest the two?
>
> There is a certain order that parameter expansions and globs happen
> relative to eachother [...] In short, no(t as far as I know).

Correct, this can't be done as a nested expansion, except by invoking
a subshell to perform the globbing.

A=(${${(@f):-$(print -rl .z*(.N))}:#*(comp|hist)*})

However, with extendedglob this specific example can be done entirely
with globbing:

A=( .z*~*(comp|hist)*(.N) )

Re: glob inside nested parameter expansion returns glob string

[Jim]

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Thanks everyone for the responses.

On Thu, Apr 21, 2022 at 2:15 PM Bart Schaefer <schaefer@brasslantern.com>
wrote:

> On Thu, Apr 21, 2022 at 11:51 AM Mikael Magnusson <mikachu@gmail.com>
> wrote:
> >
> > On 4/21/22, Jim <linux.tech.guy@gmail.com> wrote:
> > >
> > > % A=(${:-.z*(.N)})
> > > % A=(${A:#*(comp|hist)*})
> > >
> > > Is there a way to nest the two?
> >
> > There is a certain order that parameter expansions and globs happen
> > relative to eachother [...] In short, no(t as far as I know).
>
> Correct, this can't be done as a nested expansion, except by invoking
> a subshell to perform the globbing.
>
> A=(${${(@f):-$(print -rl .z*(.N))}:#*(comp|hist)*})
>

Came fairly close on this one while trying different ways.  Didn't use a
print
command. :-(

However, with extendedglob this specific example can be done entirely
> with globbing:
>
> A=( .z*~*(comp|hist)*(.N) )
>

Is there a typo or something missing here? This didn't find any files when I
cut and pasted it in a shell.

ZSH_VERSION  5.8
ZSH_PATCHLEVEL  debian/5.8-6+deb11u1

Again, thanks,

Jim Murphy

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Re: glob inside nested parameter expansion returns glob string

[Jim]

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Sorry, thought I had extendedglob set, works fine.

On Thu, Apr 21, 2022 at 3:37 PM Jim <linux.tech.guy@gmail.com> wrote:

> Thanks everyone for the responses.
>
> On Thu, Apr 21, 2022 at 2:15 PM Bart Schaefer <schaefer@brasslantern.com>
> wrote:
>
>> On Thu, Apr 21, 2022 at 11:51 AM Mikael Magnusson <mikachu@gmail.com>
>> wrote:
>> >
>> > On 4/21/22, Jim <linux.tech.guy@gmail.com> wrote:
>> > >
>> > > % A=(${:-.z*(.N)})
>> > > % A=(${A:#*(comp|hist)*})
>> > >
>> > > Is there a way to nest the two?
>> >
>> > There is a certain order that parameter expansions and globs happen
>> > relative to eachother [...] In short, no(t as far as I know).
>>
>> Correct, this can't be done as a nested expansion, except by invoking
>> a subshell to perform the globbing.
>>
>> A=(${${(@f):-$(print -rl .z*(.N))}:#*(comp|hist)*})
>>
>
> Came fairly close on this one while trying different ways.  Didn't use a
> print
> command. :-(
>
> However, with extendedglob this specific example can be done entirely
>> with globbing:
>>
>> A=( .z*~*(comp|hist)*(.N) )
>>
>
> Is there a typo or something missing here? This didn't find any files when
> I
> cut and pasted it in a shell.
>
> ZSH_VERSION  5.8
> ZSH_PATCHLEVEL  debian/5.8-6+deb11u1
>
> Again, thanks,
>
> Jim Murphy
>

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