Variable: project-vc-external-roots-function

project-vc-external-roots-function is a variable defined in project.el.gz.

Documentation

Function that returns a list of external roots.

It should return a list of directory roots that contain source files related to the current buffer.

The directory names should be absolute. Used in the VC-aware project backend implementation of project-external-roots.

Source Code

;; Defined in /usr/src/emacs/lisp/progmodes/project.el.gz
;;;###autoload(put 'project-vc-extra-root-markers 'safe-local-variable (lambda (val) (and (listp val) (not (memq nil (mapcar #'stringp val))))))

;; FIXME: Using the current approach, major modes are supposed to set
;; this variable to a buffer-local value.  So we don't have access to
;; the "external roots" of language A from buffers of language B, which
;; seems desirable in multi-language projects, at least for some
;; potential uses, like "jump to a file in project or external dirs".
;;
;; We could add a second argument to this function: a file extension,
;; or a language name.  Some projects will know the set of languages
;; used in them; for others, like the VC-aware type, we'll need
;; auto-detection.  I see two options:
;;
;; - That could be implemented as a separate second hook, with a
;;   list of functions that return file extensions.
;;
;; - This variable will be turned into a hook with "append" semantics,
;;   and each function in it will perform auto-detection when passed
;;   nil instead of an actual file extension.  Then this hook will, in
;;   general, be modified globally, and not from major mode functions.
;;
;; The second option seems simpler, but the first one has the
;; advantage that the user could override the list of languages used
;; in a project via a directory-local variable, thus skipping
;; languages they're not working on personally (in a big project), or
;; working around problems in language detection (the detection logic
;; might be imperfect for the project in question, or it might work
;; too slowly for the user's taste).
(defvar project-vc-external-roots-function (lambda () tags-table-list)
  "Function that returns a list of external roots.

It should return a list of directory roots that contain source
files related to the current buffer.

The directory names should be absolute.  Used in the VC-aware
project backend implementation of `project-external-roots'.")