bug#56509: [PATCH] 29.0.50; Eshell variable aliases don't fully support indexing

[Jim Porter]

On 7/11/2022 7:47 PM, Jim Porter wrote:
> Normally in Eshell, you can index variables to get the nth element, e.g. 
> "echo $exec-path[0]" would print the first element in your `exec-path' 
> variable. However, this doesn't always work for "alias" variables. From 
[snip]
> There's also a related issue with alias variables that reference other 
> alias variables...
The attached patches fix these issues. To help make this a bit easier to 
follow, the first patch just adds tests and documentation. The only code 
change I made was to move the '$INSIDE_EMACS' alias from em-dirs.el to 
esh-var.el. That's because, in theory, a person might choose not to use 
em-dirs.el (e.g. if they wanted their own implementation of directory 
handling), and it would be pretty surprising for the '$INSIDE_EMACS' 
variable to go away then too.

The second patch fixes the behavior of alias variables pointing to other 
alias variables. While this is technically a change in existing 
behavior, I think it's what the code intended, given the pre-existing 
documentation for the '$+' variable.

Finally, the third patch makes sure indexing works on all the alias 
variables. I tweaked the behavior of a couple of the alias variable 
functions and also added a flag to members of 
`eshell-variable-aliases-list' to use the "simple" behavior of passing 
the result to `eshell-apply-indices'.

0001-Improve-tests-organization-for-built-in-variables.patch
Description: Text document

0002-Allow-Eshell-variable-aliases-to-point-to-other-alia.patch
Description: Text document

0003-Ensure-Eshell-variable-aliases-properly-handle-index.patch
Description: Text document