Expand each array element with ${(P)...}

Expand each array element with ${(P)...}

[Marlon Richert]

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I have an array of variable names that I would like to expand to an array
of these variables' values.

I was expecting that if $names is an array, then ${(P)names} – or perhaps
something like ${(PA)names[@]} – would perform ${(P)...} expansion on each
element, but it doesn't. It just expands the first element in the array
instead and leaves out the rest.

Is there any way to make this work without using a for loop? I could not
find any combination of (nested) expansion flags that does what I want.

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Re: Expand each array element with ${(P)...}

[Roman Perepelitsa]

On Tue, Feb 6, 2024 at 7:51 AM Marlon Richert <marlon.richert@gmail.com> wrote:
>
> I have an array of variable names that I would like to expand to an
> array of these variables' values.

You could use this (requires extended_glob):

  ${names/(#m)*/${(P)MATCH}}

Or this, if you need to retain empty elements:

  "${(@)names/(#m)*/${(P)MATCH}}"

I don't know if there is a better way.

Roman.

Re: Expand each array element with ${(P)...}

[Lawrence Velázquez]

On Tue, Feb 6, 2024, at 2:25 AM, Roman Perepelitsa wrote:
> I don't know if there is a better way.

I'm not sure there is.  If you nest (P) to delay its application,
the shell explicitly complains about the very thing Marlon wants
to do:

	% names=(a b c)
	% : ${${(P)names}}
	zsh: parameter name reference used with array

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vq