Perhaps we're using different completion tools.  A more expansive list
doesn't bother me.

Let's see what Dmitry and Juri have to add.

On Sun, Feb 16, 2025 at 1:09 PM Eshel Yaron <me@eshelyaron.com> wrote:

> Eshel Yaron <me@eshelyaron.com> writes:
>
> > Hi,
> >
> > Ship Mints <shipmints@gmail.com> writes:
> >
> >> I tried your code to do a side-by-side but:
> >>
> >> Debugger entered--Lisp error: (wrong-number-of-arguments
> read-directory-name 6)
> >>   (read-directory-name prompt nil nil nil nil (let ((ps (mapcar
> #'(lambda (p) (expand-file-name ...))
> >> project--list))) #'(lambda (dir) (catch 'ball (let ((tail ps)) (while
> tail (let ... ... ...)))))))
> >
> > Try with a current build from master :)
> >
> >> In any case, my approach produces all legitimate possibilities a user
> could want to clear projects under any
> >> common prefix, including "/" (which means forget everything), common
> prefixes for remote directories, common
> >> roots for multiple projects at the same level and common roots up the
> tree for projects that are in a deeper
> >> hierarchy.  This is effectively what I think people would want, and I
> assume you agree.
> >
> > I don't: that's the flat list which I find inappropriate in this case.
> > Projects may (and do) reside all over the filesystem, so producing all
> > possible prefixes of one or more project roots amounts to a huge list
> > with potentially many irrelevant entries.  Here I prefer completing the
> > directory name incrementally, by following the filesystem hierarchy,
> > with the usual Emacs file/directory name completion.
> >
> >> If your code produces the same and is more efficient, that's great.
> >
> > My suggestion basically preserves the current behavior, it just filters
> > the directories you can complete at each level to only include those
> > that actually lead to one or more project roots.
>
>
> BTW, here's a slightly improved project-read-ancestor-directory, it uses
> try-completion to check if a candidate directory is a prefix of any
> project root, which seems to be faster than the Lisp implementation I
> tried at first:
>
> --8<---------------cut here---------------start------------->8---
> (defun project-read-ancestor-directory (prompt)
>   "Prompt with PROMPT for an ancestor directory of one or more project
> roots."
>   (project--ensure-read-project-list)
>   (read-directory-name
>    prompt nil nil nil nil
>    (let ((ps (mapcar (lambda (p) (expand-file-name (car p)))
> project--list)))
>      (lambda (dir) (try-completion (expand-file-name dir) ps)))))
> --8<---------------cut here---------------end--------------->8---
>