Fwiw, Danny's tip is what I used at a recent day job gig for defining
subprojects in a 400k files repo.

João

On Wed, Nov 16, 2022, 22:39 Danny Freeman <danny@dfreeman.email> wrote:

>
> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
> > Hi,
> >
> > Here's another issue that's technically a emacs.help question, but might
> > result in some code/documentation updates, so I'm sending it here.
> >
> > My main day-job code base is an AWS CloudFormation monstrosity involving
> > several Python Lambdas, among other things. Basic project structure
> > looks like:
> >
> > project_root
> > ├── .git
> > ├── src
> > │   └── python
> > │       ├── VeryImportantLambda
> > │       │   └── .venv
> > │       ├── MoreImportance
> > │       │   └── .venv
> > │       ├── RunInCaseOfEmergency
> > │       │   └── .venv
> >
> > I'm using the python-lsp-server python package in each Python
> > subdirectory, and the key is that each of those directories is a virtual
> > environment that needs to stay isolated from the others. Each has
> > different packages installed, and in some cases even the Python versions
> > are different (though I'm trying to get rid of that).
> >
> > When I was using lsp-mode this wasn't difficult, because lsp-mode and
> > project.el are essentially orthogonal: if I visited a python file in a
> > given lambda directory, I could use `pyvenv-activate' to activate that
> > environment, and then the `lsp' invocation would confine itself to
> > python files within the environment. Project.el just provided
> > project-wide navigation.
> >
> > Now I'm trying to move to Eglot, and there is tighter integration
> > between Eglot and project.el. Turning on Eglot in one lambda starts the
> > server for all Python libraries in the whole project, not just the
> > current environment. I looked into constructing my own version of the
> > call to `eglot', but it is tightly tied to a project, all the way down.
> >
> > Is anyone else handling this situation? Any suggestions how to make it
> > work?
> >
> > Thanks,
> > Eric
>
>
> I have NOT been in this situation, but it sounds like you want to keep
> using project.el as is, but override eglot's usage of project.el to
> identify root directory to start a lsp server in.
>
> I think the place to start looking would be the function
> `eglot--current-project`.
>
> It uses a var called `eglot-lsp-context` which is `t` when eglot is
> searching for a project.
>
> Knowing this, there is another var called `project-find-functions` that
> project.el uses when searching for project roots, which can be used for
> finding custom project roots. I have one that looks for a file named
> ".project.el". If that file exists then that directory is identified as
> a project. It's really useful when you have a project not in source
> control.
>
> See:
> ```
> (defun project-find-project.el (dir)
>   "Returns a `manual-project' instance if the project of the current
> DIR has a .project.el file in its root directory."
>   (let ((root (locate-dominating-file dir ".project.el")))
>     (when root
>       (cons 'transient root))))
>
> (add-hook 'project-find-functions #'project-find-project.el)
> ```
>
> Now, I am not a python programmer, but lets pretend that python
> virtualenviroment depends on a file located in the directory you want to
> activate one of these virtual environments, say `.virtualenv`.
>
> You can write a project-find-functions implementation that looks for
> these virutalenv files ONLY when eglot-lsp-context is active.
>
> ```
> (defun project-find-virtualenv-for-eglot (dir)
>   (when eglot-lsp-context
>     (let ((root (locate-dominating-file dir ".virtualenv")))
>       (when root
>         (cons 'transient root)))))
>
> (add-hook 'project-find-functions #'project-find-virtualenv-for-eglot)
> ```
>
> I did not test this, but I think it should send you down the right path.
> Eglot should see your aws lambda folders as the project root, and
> project.el should see the parent.
>
> If python virtual environments do not have any kind of file marker in
> the filesystem, you could use a dummy file in those directories like
> `.eglot-project` or something.
>
> Hope this helps,
> --
> Danny Freeman
>
>