Dmitry Gutov <dmitry@gutov.dev> writes:
> On 11/07/2023 02:45, Spencer Baugh wrote:
>> Dmitry Gutov <dmitry@gutov.dev> writes:
>>> On 27/06/2023 23:01, Spencer Baugh wrote:
>>>> OK, how about this?
>>>
>>> Maybe we should go in the other direction? And call
>>> abbreviate-file-name on them?
>>>
>>> Because otherwise in project-prompt-project-dir we'll always show the
>>> expanded directory names, taking up extra space and usually repeating
>>> the full name of the user's home directory for no good reason.
>> That seems reasonable if we let-bind directory-abbrev-alist to nil
>> around it; otherwise we'll be dependent on the user's configuration and
>> we might add a directory in one way, and then they add a new value to
>> directory-abbrev-alist and we add it again a second way.
>
> That's also fair.
>
>> Although maybe that's fine?  And probably users of
>> directory-abbrev-alist would like to have those abbreviations show up in
>> project-prompt-project-dir.
>
> They probably would. But indeed if the list was saved with one
> configuration, and read with another, it could lead to a mistake.
>
>> Also we could always call abbreviate-file-name at
>> project-prompt-project-dir time.
>
> Meaning it will be called N times (for the number of projects) every
> time the list is displayed, instead of just once, when the project is
> saved/visited. But maybe it's fine too? How slow could that be?

I was sad about this but I think I've got the solution now: We just
maintain project--list in abbreviated form and project-list-file in
expanded form.

I think that solves all the problems: the persistent file is independent
of user configuration, so if the user changes their abbreviations
they'll get new ones the next time the file is read (presumably the next
time they run Emacs).  But project--list is abbreviated, so
project-prompt-project-dir gets abbreviated dirs.

It does mean that if they change their directory-abbrev-alist while
Emacs is running they could get duplicate entries, but that already
could happen before this patch, and it's not a big problem IMO.

See patch below.