Subject: Re: bug#67249: 30.0.50; `same-frame` equivalent for `display-buffer-alist`

From: Stefan Monnier <[email-masked]>
Date: Sat, 09 Dec 2023 17:29:06 -0500

> Before pushing it, please try to fix the corresponding sections in the
> Elisp manual.  It will be non-trivial to avoid confusions with the old
> 'pop-up-frames' option.

How 'bout the patch below?

        Stefan
diff --git a/doc/lispref/windows.texi b/doc/lispref/windows.texi
index 22c1b307252..7649013fce4 100644
--- a/doc/lispref/windows.texi
+++ b/doc/lispref/windows.texi
@@ -3433,9 +3433,13 @@ Choosing Window Options
 @end defopt
 
 @defopt pop-up-frames
-If the value of this variable is non-@code{nil}, that means
-@code{display-buffer} may display buffers by making new frames.  The
-default is @code{nil}.
+If the value of this parameter is non-@code{nil}, that means
+@code{display-buffer} may display buffers by making new frames.
+It can be specified in two ways: via the @code{pop-up-frames}
+variable and via a @code{pop-up-frames} entry in
+@code{display-buffer}'s @var{alist},
+where the entry in the alist takes precedence over the variable.
+The default is @code{nil}.
 
 A non-@code{nil} value also means that when @code{display-buffer} is
 looking for a window already displaying @var{buffer-or-name}, it can
diff --git a/etc/NEWS b/etc/NEWS
index 60391cfb22e..060d1a2fe5c 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1289,6 +1289,10 @@ values.
 
 * Lisp Changes in Emacs 30.1
 
+** New 'pop-up-frames' action alist entry for 'display-buffer'.
+This has the same effect as the variable of the same name and takes
+precedence over the variable when present.
+
 ** New function 'merge-ordered-lists'.
 Mostly used internally to do a kind of topological sort of
 inheritance hierarchies.
diff --git a/lisp/window.el b/lisp/window.el
index fbdcd611068..93c8ad7fad9 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -6862,6 +6862,7 @@ special-display-popup-frame
 If ARGS is a list whose car is a symbol, use (car ARGS) as a
 function to do the work.  Pass it BUFFER as first argument, and
 pass the elements of (cdr ARGS) as the remaining arguments."
+  (declare (obsolete display-buffer-pop-up-frame "30.1"))
   (if (and args (symbolp (car args)))
       (apply (car args) buffer (cdr args))
     (let ((window (get-buffer-window buffer 0)))
@@ -6881,9 +6882,8 @@ special-display-popup-frame
        ;; Stay on the same frame if requested.
        (when (or (cdr (assq 'same-frame args)) (cdr (assq 'same-window args)))
 	 (let* ((pop-up-windows t)
-		pop-up-frames
 		special-display-buffer-names special-display-regexps)
-	   (display-buffer buffer)))
+	   (display-buffer buffer '((pop-up-frames . nil)))))
        ;; If no window yet, make one in a new frame.
        (let* ((frame
 	       (with-current-buffer buffer
@@ -6996,6 +6996,13 @@ pop-up-frames
 	  (const :tag "Always" t))
   :group 'windows)
 
+(defun window--pop-up-frames (alist)
+ (let* ((override (assq 'pop-up-frames alist))
+        (pop-up (if override (cdr overriding) pop-up-frames)))
+   (if (eq pop-up 'graphic-only)
+       (display-graphic-p)
+     pop-up)))
+
 (defcustom display-buffer-reuse-frames nil
   "Non-nil means `display-buffer' should reuse frames.
 If the buffer in question is already displayed in a frame, raise
@@ -7742,6 +7749,8 @@ display-buffer
     Possible values are nil (the selected frame), t (any live
     frame), visible (any visible frame), 0 (any visible or
     iconified frame) or an existing live frame.
+ `pop-up-frames' -- Same effect as the eponymous variable.
+    Takes precedence over the variable.
  `pop-up-frame-parameters' -- The value specifies an alist of
     frame parameters to give a new frame, if one is created.
  `window-height' -- The value specifies the desired height of the
@@ -7830,12 +7839,12 @@ display-buffer
                           user-action special-action action extra-action
                           display-buffer-base-action
                           display-buffer-fallback-action))
-           (functions (apply 'append
+           (functions (apply #'append
                              (mapcar (lambda (x)
                                        (setq x (car x))
                                        (if (functionp x) (list x) x))
                                      actions)))
-           (alist (apply 'append (mapcar 'cdr actions)))
+           (alist (apply #'append (mapcar #'cdr actions)))
            window)
       (unless (buffer-live-p buffer)
         (error "Invalid buffer"))
@@ -7978,9 +7987,7 @@ display-buffer-reuse-window
 indirectly called by the latter."
   (let* ((alist-entry (assq 'reusable-frames alist))
 	 (frames (cond (alist-entry (cdr alist-entry))
-		       ((if (eq pop-up-frames 'graphic-only)
-			    (display-graphic-p)
-			  pop-up-frames)
+		       ((window--pop-up-frames alist)
 			0)
 		       (display-buffer-reuse-frames 0)
 		       (t (last-nonminibuffer-frame))))
@@ -8034,9 +8041,7 @@ display-buffer-reuse-mode-window
   (let* ((alist-entry (assq 'reusable-frames alist))
          (alist-mode-entry (assq 'mode alist))
 	 (frames (cond (alist-entry (cdr alist-entry))
-		       ((if (eq pop-up-frames 'graphic-only)
-			    (display-graphic-p)
-			  pop-up-frames)
+		       ((window--pop-up-frames alist)
 			0)
 		       (display-buffer-reuse-frames 0)
 		       (t (last-nonminibuffer-frame))))
@@ -8182,9 +8187,7 @@ display-buffer--maybe-pop-up-frame
 ALIST is an association list of action symbols and values.  See
 Info node `(elisp) Buffer Display Action Alists' for details of
 such alists."
-  (and (if (eq pop-up-frames 'graphic-only)
-	   (display-graphic-p)
-	 pop-up-frames)
+  (and (window--pop-up-frames alist)
        (display-buffer-pop-up-frame buffer alist)))
 
 (defun display-buffer--maybe-pop-up-window (buffer alist)
@@ -8548,9 +8551,7 @@ display-buffer-in-previous-window
 	  (cdr (assq 'inhibit-same-window alist)))
 	 (frames (cond
 		  (alist-entry (cdr alist-entry))
-		  ((if (eq pop-up-frames 'graphic-only)
-		       (display-graphic-p)
-		     pop-up-frames)
+		  ((window--pop-up-frames alist)
 		   0)
 		  (display-buffer-reuse-frames 0)
 		  (t (last-nonminibuffer-frame))))