Re: "local -g" declaration references local var in enclosing scope

[Chet Ramey]

On 3/11/24 8:26 AM, Adrian Ho wrote:
> Thanks much for all the insights, everyone! Indeed, the man page isn't
> clear on how to reason about `local -g`. I'm now left with the following
> understanding:
>
> 1. There is *nothing local* about `local -g`; it operates entirely at the
> global level.

It exists to allow shell functions to create variables at the global scope
with attributes that require the use of `declare', which is not possible
without `-g'.


> In particular, it does *not* create a local reference to a
> global var, which is the natural assumption given the typical behaviour of
> `declare/local`.

I would disagree that this assumption is `natural'.

> 2. Because of this, there is no way to *read* a global var if a calling
> scope declares a shadowing var, short of unsetting that shadow var.

This is how dynamic scoping works.


> The `-g` option forces variables to be created or modified at the global
> scope, even when `declare` is executed in a shell function.
>
> to:
>
> The `-g` option forces variables to be created or modified at the global
> scope, even when `declare` is executed in a shell function, *and no
> references to these variables are created in that function's scope*.

I disagree that this particular addition is needed. I'd be happy to
entertain other suggestions about how to clarify the documentation.

Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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