bug#42532: 28.0.50; Can eldoc-prefer-doc-buffer be more aggressive?

[João Távora]

João Távora <joaotavora@gmail.com> writes:

> Regardless, I think it's reasonable to add a third possible value 
> for eldoc-prefer-doc-buffer (which should really be renamed 
> eldoc-echo-area-prefer-doc-buffer).  The value could be the symbol
> 'aggressive or 'aggressively.  Then it would behave as you propose:
> if the ElDoc doc buffer is showing, the echo area display code is 
> a noop.
>
> What do you think?

Instead of an abstract idea, here's an actual patch you can try on top
of the current eldoc.el

diff --git a/lisp/emacs-lisp/eldoc.el b/lisp/emacs-lisp/eldoc.el
index 772c907c28..2eae30f004 100644
--- a/lisp/emacs-lisp/eldoc.el
+++ b/lisp/emacs-lisp/eldoc.el
@@ -111,13 +111,19 @@ eldoc-echo-area-use-multiline-p
  symbol names if it will\ enable argument list to fit on one
  line" truncate-sym-name-if-fit)))
 
-(defcustom eldoc-prefer-doc-buffer nil
+(define-obsolete-variable-alias 'eldoc-prefer-doc-buffer
+  'eldoc-echo-area-prefer-doc-buffer "eldoc-1.11.0")
+(defcustom eldoc-echo-area-prefer-doc-buffer nil
   "Prefer ElDoc's documentation buffer if it is showing in some frame.
 If this variable's value is t and a piece of documentation needs
-to be truncated to fit in the echo area, do so if ElDoc's
+to be truncated to fit in the echo area, do so if ElDoc's only
 documentation buffer is not already showing, since the buffer
-always holds the full documentation."
-  :type 'boolean)
+always holds the full documentation.  If the value is
+`aggressively' do so even if the documentation doesn't need to be
+truncated."
+  :type '(radio (const :tag "Yes" t)
+                (const :tag "Yes, aggressively." 'aggressively)
+                (const :tag "No" nil)))
 
 (defface eldoc-highlight-function-argument
   '((t (:inherit bold)))
@@ -458,7 +464,8 @@ eldoc--handle-docs
                       (t 1)))
          (things-reported-on)
          (request eldoc--last-request-state)
-         single-doc single-doc-sym)
+         single-doc single-doc-sym
+         (eldoc-buffer-showing (get-buffer-window eldoc--doc-buffer)))
       ;; Then, compose the contents of the `*eldoc*' buffer.
       (with-current-buffer (eldoc-doc-buffer)
         ;; Set doc-buffer's `eldoc--last-request-state', too
@@ -490,6 +497,9 @@ eldoc--handle-docs
       ;; function into some `eldoc-display-functions' special hook.
       (let ((echo-area-message
              (cond
+              ((and eldoc-buffer-showing
+                    (eq eldoc-echo-area-prefer-doc-buffer 'aggressively))
+               nil)
               (;; We handle the `truncate-sym-name-if-fit' special
                ;; case first, by checking if for a lot of special
                ;; conditions.
@@ -519,8 +529,8 @@ eldoc--handle-docs
                   (while (and (not (bobp)) (bolp)) (goto-char 
(line-end-position 0)))
                   finally
                   (unless (and truncated
-                               eldoc-prefer-doc-buffer
-                               (get-buffer-window eldoc--doc-buffer))
+                               (eq eldoc-echo-area-prefer-doc-buffer t)
+                               eldoc-buffer-showing)
                     (cl-return
                      (concat
                       (buffer-substring (point-min) (point))