Dmitry Gutov <dmitry@gutov.dev> writes:
> On 15/11/2023 22:49, Spencer Baugh wrote:
>> project--list is the new history variable.  Using it is mostly trivial;
>> a small bit of work is necessary in project-prompt-project-name to get
>> project-names for the history, but that worked out great.  Everything
>> else just seems to work.
>> And with savehist-mode enabled, project--list just gets stored
>> automatically without any code in project.el.
>> I can implement a backwards-compatible version if this seems like a
>> reasonable direction to go in.
>
> I haven't tried using it, but there's indeed a lot to like about this patch.
>
> What happens if savehist-mode is nil, though? Which it is by
> default. For users with this setup the project history will just
> disappear.

Indeed.

> What kind of backward compatibility did you have in mind?

I was thinking about either keeping our code for saving to
project-list-file around in some obsoleted form, or using a subset of
the savehist code to save only project--list when it's not otherwise
enabled.

But actually, maybe it's time that we just enable savehist by default.
I'll try that first - I mailed emacs-devel about it.  Then we could
delete our project-list-file code once project.el eventually starts
requiring Emacs 30.

Regardless, how about the below patch which changes the default behavior
to only write project-list-file when Emacs exits?  I think this is a
useful first step no matter what else we do, since it matches the
behavior of savehist better.