Re: Project local variables.

[Stephen Leake <stephen_leake@stephe-leake.org>]

Ergus <spacibba@aol.com> writes:

> Looking at the evolution of project.el I want to know if there is any
> sort of project local environment/namespace/scope. The idea is to
> provide some variables that could be shared by all the files in the same
> project but that could be modified by external-packages at the elisp
> level. something like "setq-project"??

You can derive a new project type:

(cl-defstruct my-prj
  name     ;; A user-friendly string, used in menus and messages.

  variable-1
  variable-2
  ...
  )

add a project-find-functions for it:

(defun my-prj-find (dir)
...
)
(add-hook 'project-find-functions #'my-prj-find 90)

and then define new project ops that use the variable for it:

(cl-defgeneric my-method-1 ((_project wisi-prj))
 ...
 )

The GNU ELPA wisi package takes this approach.

But I suspect you are asking for something more lightweight.

> A use case is for example when working in tramp some operations are
> expensive like looking for an executable in the remote system. The
> search could be made only once; but then if a local file is open the
> cached value will be wrong. 

For this specific case, adding an optional cache to tramp seems like a
better approach. Perhaps that just means creating a new file handler
that wraps the tramp one with a cache?

You could use the above approach to define a project whose files are in
a remote directory accessed via tramp, but that doesn't work if you want
all the normal emacs functions that access files via file handlers to
use the cache. So I don't see how a project-local variable would help.

-- 
-- Stephe

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