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27.8 The Buffer List

The buffer list is a list of all live buffers. The order of the buffers in this list is based primarily on how recently each buffer has been displayed in a window. Several functions, notably other-buffer, use this ordering. A buffer list displayed for the user also follows this order.

Creating a buffer adds it to the end of the buffer list, and killing a buffer removes it from that list. A buffer moves to the front of this list whenever it is chosen for display in a window (see Switching Buffers) or a window displaying it is selected (see Selecting Windows). A buffer moves to the end of the list when it is buried (see bury-buffer, below). There are no functions available to the Lisp programmer which directly manipulate the buffer list.

In addition to the fundamental buffer list just described, Emacs maintains a local buffer list for each frame, in which the buffers that have been displayed (or had their windows selected) in that frame come first. (This order is recorded in the frame’s buffer-list frame parameter; see Buffer Parameters.) Buffers never displayed in that frame come afterward, ordered according to the fundamental buffer list.

function buffer-list \&optional frame​

This function returns the buffer list, including all buffers, even those whose names begin with a space. The elements are actual buffers, not their names.

If frame is a frame, this returns frame’s local buffer list. If frame is nil or omitted, the fundamental buffer list is used: the buffers appear in order of most recent display or selection, regardless of which frames they were displayed on.

(buffer-list)
     ⇒ (#<buffer buffers.texi>
         #<buffer  *Minibuf-1*> #<buffer buffer.c>
         #<buffer *Help*> #<buffer TAGS>)
;; Note that the name of the minibuffer
;;   begins with a space!
(mapcar #'buffer-name (buffer-list))
    ⇒ ("buffers.texi" " *Minibuf-1*"
        "buffer.c" "*Help*" "TAGS")

The list returned by buffer-list is constructed specifically; it is not an internal Emacs data structure, and modifying it has no effect on the order of buffers. If you want to change the order of buffers in the fundamental buffer list, here is an easy way:

(defun reorder-buffer-list (new-list)
  (while new-list
    (bury-buffer (car new-list))
    (setq new-list (cdr new-list))))

With this method, you can specify any order for the list, but there is no danger of losing a buffer or adding something that is not a valid live buffer.

To change the order or value of a specific frame’s buffer list, set that frame’s buffer-list parameter with modify-frame-parameters (see Parameter Access).

function other-buffer \&optional buffer visible-ok frame​

This function returns the first buffer in the buffer list other than buffer. Usually, this is the buffer appearing in the most recently selected window (in frame frame or else the selected frame, see Input Focus), aside from buffer. Buffers whose names start with a space are not considered at all.

If buffer is not supplied (or if it is not a live buffer), then other-buffer returns the first buffer in the selected frame’s local buffer list. (If frame is non-nil, it returns the first buffer in frame’s local buffer list instead.)

If frame has a non-nil buffer-predicate parameter, then other-buffer uses that predicate to decide which buffers to consider. It calls the predicate once for each buffer, and if the value is nil, that buffer is ignored. See Buffer Parameters.

If visible-ok is nil, other-buffer avoids returning a buffer visible in any window on any visible frame, except as a last resort. If visible-ok is non-nil, then it does not matter whether a buffer is displayed somewhere or not.

If no suitable buffer exists, the buffer *scratch* is returned (and created, if necessary).

function last-buffer \&optional buffer visible-ok frame​

This function returns the last buffer in frame’s buffer list other than buffer. If frame is omitted or nil, it uses the selected frame’s buffer list.

The argument visible-ok is handled as with other-buffer, see above. If no suitable buffer can be found, the buffer *scratch* is returned.

command bury-buffer \&optional buffer-or-name​

This command puts buffer-or-name at the end of the buffer list, without changing the order of any of the other buffers on the list. This buffer therefore becomes the least desirable candidate for other-buffer to return. The argument can be either a buffer itself or the name of one.

This function operates on each frame’s buffer-list parameter as well as the fundamental buffer list; therefore, the buffer that you bury will come last in the value of (buffer-list frame) and in the value of (buffer-list). In addition, it also puts the buffer at the end of the list of buffers of the selected window (see Window History) provided it is shown in that window.

If buffer-or-name is nil or omitted, this means to bury the current buffer. In addition, if the current buffer is displayed in the selected window, this makes sure that the window is either deleted or another buffer is shown in it. More precisely, if the selected window is dedicated (see Dedicated Windows) and there are other windows on its frame, the window is deleted. If it is the only window on its frame and that frame is not the only frame on its terminal, the frame is dismissed by calling the function specified by frame-auto-hide-function (see Quitting Windows). Otherwise, it calls switch-to-prev-buffer (see Window History) to show another buffer in that window. If buffer-or-name is displayed in some other window, it remains displayed there.

To replace a buffer in all the windows that display it, use replace-buffer-in-windows, See Buffers and Windows.

command unbury-buffer​

This command switches to the last buffer in the local buffer list of the selected frame. More precisely, it calls the function switch-to-buffer (see Switching Buffers), to display the buffer returned by last-buffer (see above), in the selected window.

variable buffer-list-update-hook​

This is a normal hook run whenever the buffer list changes. Functions (implicitly) running this hook are get-buffer-create (see Creating Buffers), rename-buffer (see Buffer Names), kill-buffer (see Killing Buffers), bury-buffer (see above) and select-window (see Selecting Windows).

Functions run by this hook should avoid calling select-window with a nil norecord argument or with-temp-buffer since either may lead to infinite recursion.