Re: A unified project root interface

[Sudish Joseph <sudish@gmail.com>]

David Engster <deng@randomsample.de> writes:
> You can create a project like this with ede-generic, but then you have
> to write a little defclass inheriting from ede-generic, call
> ede-generic-new-autoloader, and to actually *do* something when the
> project is loaded you have to define methods like
> `ede-generic-setup-configuration'. This is just too much boilerplate for
> such a simple thing like the above. Also, even most Emacs developers are
> not familiar with the CLOS-like syntax that's needed to define those
> things.
>
> There's no doubt that EDE can do all what's needed, but is has to be
> wrapped in something that's easier to use, at least for simple stuff
> like what project-roots.el does.

The simplest - and for me, only - use is to ask a buffer which project
it belongs to, if any.  Everything else in my usage can be derived from
that.  This is how vc works, too, I think, and ibuffer-vc can aggregate
buffers by vc-roots handily.

Buffers and buffer-locals provide a simple and emacsy form of extensible
object and attributes, so if there's more data associated with a project
it'd be nice to expose them as such as opposed or in addition to having
a dedicated project api.  This fits with .dir-locals as well.

Most project convenience functions I need turn out to be general
directory and file functions.  For e.g., "all files in current project"
could be as simple as
	(all-files-in project-root)
where the former is generic functionality and the latter is a buffer
local.

-Sudish

PS: Some more examples of how I find having a simple buffer-local
project-root handy - I use these every day:

;; project-details is a buffer-local of
;; (matching-rule-name . project-root-dir)
(defun sj/project-root-dir ()
  (when (project-root-fetch)
    (cdr project-details)))

;; this auto-restricts recursive ack searches to current project, where
;; project is defined dynamically - vc roots, etc.
(setq ack-mode-root-directory-function 'sj/project-root-dir)


;; A couple of anything.el sources that automatically use the current
;; buffer's project root

;; Files from current project root, if any
(defconst sj/anything-source-project-root-files
  '((name . "Project Files")
    (init . (lambda ()
	      (setq anything-project-root project-details)))
    (candidates . (lambda ()
		    (project-root-file-find-process anything-pattern)))
    (candidate-transformer . sj/anything-file-candidate-filter)
    (requires-pattern . 2)
    (volatile)
    (type . file)))

;; A source that's aware of the MVC structure of a Rails project.
(defconst sj/anything-rails-files
  '((name . "Rails")
    (init . (lambda ()
	      (setq anything-project-root project-details)))
    (candidates . (lambda ()
		    (when (equal "Rails Project" (car anything-project-root))
		      (rails-list-project-files (cdr anything-project-root)))))
    (type . file)))