bug#54977: 29.0.50; Customising eshell-modules-list means you won't get new default entries

[Sean Whitton <spwhitton@spwhitton.name>]

Hello,

On Sat 16 Apr 2022 at 10:01pm -07, Jim Porter wrote:

> On 4/16/2022 1:55 PM, Sean Whitton wrote:
>> Suppose that you use the customisation interface to enable the
>> eshell-rebind module, and save the result in your init.  Now upstream
>> Emacs gains a new on-by-default module, e.g. the recently added
>> em-extpipe.  While everyone who hasn't customised eshell-modules-list
>> gets the new module automatically, you'll have to customise the variable
>> again, and you can't even just tick a box to add it, as with the other
>> truly optional modules, but must manually insert it at the end of the
>> list.  This is no good.
>
> Generally I resolve this in my config by using a combination of
> `add-to-list' and `delete' to manually customize lists like this.

Right, me too.

> Maybe it would be good to provide something like that for users of the
> Customize interface as well? Then any defcustom that takes a list
> could either be customized to have an exact set of elements (as it is
> today), or to have "the default, but with FOO added and BAR removed".

That might be a good enhancement, but I think the Eshell case is a bit
simpler -- using two defcustoms mostly solves it.

-- 
Sean Whitton