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Re: feature todo .. be able to unset vars at assignment stage , without
From: |
Greg Wooledge |
Subject: |
Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment |
Date: |
Wed, 21 Feb 2024 15:18:12 -0500 |
On Wed, Feb 21, 2024 at 08:54:30PM +0100, alex xmb sw ratchev wrote:
> say i wanna do major here and there with assigments only
> in bash has three var states
> unset , eg never ever set
> empty , set , but just empty
> filled , non empty set
I believe what he's saying is 'I would like a parameter expansion that
unsets variables, i.e. the opposite of : "${foo=bar}"'.
I could actually see this being useful. It might offer a syntactically
nicer way of writing
(unset DISPLAY; some command)
(depending on how it actually ends up working).
As far as the second paragraph goes, I don't think those "three states"
are correct. As far as bash is concerned, there's no significant
difference between a variable with an empty value, and a variable with
a non-empty value. The test command and its brethren may differentiate
between those values, but the *states* are the same.
On the other hand, there is a state where a variable has had attributes
defined (e.g. declare -i foo) but has not been created yet (has no value).
The attributes will be applied whenever the variable is actually created
in the appropriate scope.
In code, those would be:
unset -v foo
declare -i foo # or other flags
foo= # or a non-empty value
- feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, alex xmb sw ratchev, 2024/02/21
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, alex xmb sw ratchev, 2024/02/21
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Andreas Kähäri, 2024/02/21
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Lawrence Velázquez, 2024/02/21
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, alex xmb sw ratchev, 2024/02/21
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment,
Greg Wooledge <=
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Chet Ramey, 2024/02/21
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, alex xmb sw ratchev, 2024/02/22
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, alex xmb sw ratchev, 2024/02/22
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Zachary Santer, 2024/02/22
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Zachary Santer, 2024/02/22
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Greg Wooledge, 2024/02/22
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Zachary Santer, 2024/02/23
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Greg Wooledge, 2024/02/23
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, Zachary Santer, 2024/02/23
- Re: feature todo .. be able to unset vars at assignment stage , without unset util , for coding language fair extendment, alex xmb sw ratchev, 2024/02/23