38.7 Displaying Buffers in Windows

In this section we describe convenient functions that choose a window automatically and use it to display a specified buffer. These functions can also split an existing window in certain circumstances. We also describe variables that parameterize the heuristics used for choosing a window. low-level functions that give you more precise control.

Do not use the functions in this section in order to make a buffer current so that a Lisp program can access or modify it; they are too drastic for that purpose, since they change the display of buffers in windows, which is gratuitous and will surprise the user. Instead, use set-buffer (see Current Buffer) and save-excursion (see Excursions), which designate buffers as current for programmed access without affecting the display of buffers in windows.

Command: switch-to-buffer buffer-or-name &optional norecord

This function makes buffer-or-name the current buffer, and also displays the buffer in the selected window. This means that a human can see the buffer and subsequent keyboard commands will apply to it. Contrast this with set-buffer, which makes buffer-or-name the current buffer but does not display it in the selected window. See Current Buffer.

If buffer-or-name does not identify an existing buffer, then a new buffer by that name is created. The major mode for the new buffer is set according to the variable default-major-mode. See Auto Major Mode.

Normally the specified buffer is put at the front of the buffer list. This affects the operation of other-buffer. However, if norecord is non-nil, this is not done. See The Buffer List.

The switch-to-buffer function is often used interactively, as the binding of C-x b. It is also used frequently in programs. It always returns nil.

Command: switch-to-buffer-other-window buffer-or-name

This function makes buffer-or-name the current buffer and displays it in a window not currently selected. It then selects that window. The handling of the buffer is the same as in switch-to-buffer.

The currently selected window is absolutely never used to do the job. If it is the only window, then it is split to make a distinct window for this purpose. If the selected window is already displaying the buffer, then it continues to do so, but another window is nonetheless found to display it in as well.

Function: pop-to-buffer buffer-or-name &optional other-window on-frame

This function makes buffer-or-name the current buffer and switches to it in some window, preferably not the window previously selected. The “popped-to” window becomes the selected window within its frame.

If the variable pop-up-frames is non-nil, pop-to-buffer looks for a window in any visible frame already displaying the buffer; if there is one, it returns that window and makes it be selected within its frame. If there is none, it creates a new frame and displays the buffer in it.

If pop-up-frames is nil, then pop-to-buffer operates entirely within the selected frame. (If the selected frame has just a minibuffer, pop-to-buffer operates within the most recently selected frame that was not just a minibuffer.)

If the variable pop-up-windows is non-nil, windows may be split to create a new window that is different from the original window. For details, see Choosing Window.

If other-window is non-nil, pop-to-buffer finds or creates another window even if buffer-or-name is already visible in the selected window. Thus buffer-or-name could end up displayed in two windows. On the other hand, if buffer-or-name is already displayed in the selected window and other-window is nil, then the selected window is considered sufficient display for buffer-or-name, so that nothing needs to be done.

All the variables that affect display-buffer affect pop-to-buffer as well. See Choosing Window.

If buffer-or-name is a string that does not name an existing buffer, a buffer by that name is created. The major mode for the new buffer is set according to the variable default-major-mode. See Auto Major Mode.

If on-frame is non-nil, it is the frame to pop to this buffer on.

An example use of this function is found at the end of Filter Functions.

Command: replace-buffer-in-windows buffer &optional which-frames which-devices

This function replaces buffer with some other buffer in all windows displaying it. The other buffer used is chosen with other-buffer. In the usual applications of this function, you don’t care which other buffer is used; you just want to make sure that buffer is no longer displayed.

The optional arguments which-frames and which-devices have the same meaning as with delete-windows-on.

This function returns nil.