Extract eldoc--supported-p

* lisp/emacs-lisp/eldoc.el (eldoc--supported-p): New function.
(turn-on-eldoc-mode, eldoc-mode): Use it.
(http://lists.gnu.org/archive/html/emacs-devel/2017-05/msg00865.html)

1 files changed, 5 insertions, 2 deletions

diff --git a/lisp/emacs-lisp/eldoc.el b/lisp/emacs-lisp/eldoc.el
index b0f6ea4412d..40f5e2ef96a 100644
--- a/lisp/emacs-lisp/eldoc.el
+++ b/lisp/emacs-lisp/eldoc.el
@@ -186,7 +186,7 @@ expression point is on."
   :group 'eldoc :lighter eldoc-minor-mode-string
   (setq eldoc-last-message nil)
   (cond
-   ((memq eldoc-documentation-function '(nil ignore))
+   ((not (eldoc--supported-p))
     (when (called-interactively-p 'any)
       (message "There is no ElDoc support in this buffer"))
     (setq eldoc-mode nil))
@@ -213,9 +213,12 @@ expression point is on."
 (defun turn-on-eldoc-mode ()
   "Turn on `eldoc-mode' if the buffer has eldoc support enabled.
 See `eldoc-documentation-function' for more detail."
-  (unless (memq eldoc-documentation-function '(nil ignore))
+  (when (eldoc--supported-p)
     (eldoc-mode 1)))
 
+(defun eldoc--supported-p ()
+  (not (memq eldoc-documentation-function '(nil ignore))))
+
 
 (defun eldoc-schedule-timer ()
   (or (and eldoc-timer