bug#55838: 29.0.50; [PATCH] Eshell string-split subscript indexing splits too much

[Jim Porter]

On 6/7/2022 6:36 PM, Jim Porter wrote:
>  From "emacs -Q -f eshell":
>
>    M-: (setq foo "a\nb:c")
>
>    ~ $ echo $foo
>    a
>    b:c
>    ~ $ echo $foo[: 0]
>    ("a" "b")
>
> The first command is normal, and just shows that Eshell outputs the 
> string with no manipulation. In the second command, we split the string 
> on ":" and get the 0th element. However, that gets split *again* (on 
> newlines) and returns a list.

Here's a patch for this. It changes the behavior of 
`eshell-apply-indices' to use `eshell-convert-to-number' (when the 
expansion isn't wrapped in double-quotes) instead of the more-aggressive 
`eshell-convert'. I think `eshell-convert-to-number' is the right thing 
here, since Eshell already converts number-like strings to actual 
numbers in most cases.

As a note, if you wanted the old behavior, you could do something like this:

  ~ $ echo $foo[: 0][0 1]
  ("a" "b")

There's also a suggestion in the "Bugs and ideas" section of the Eshell 
manual to add "*" as a subscript to mean "all indices", so you could do 
the above in a more generic fashion like:

  ~ $ echo $foo[: 0][*]
  ;; Doesn't currently work, but it could.

0001-Don-t-split-Eshell-expansions-by-line-when-using-spl.patch
Description: Text document