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The command display-buffer flexibly chooses a window for
display, and displays a specified buffer in that window. It can be
called interactively, via the key binding C-x 4 C-o. It is also
used as a subroutine by many functions and commands, including
switch-to-buffer and pop-to-buffer (see Switching Buffers).
This command performs several complex steps to find a window to
display in. These steps are described by means of display
actions, which have the form (function . alist).
Here, function is either a function or a list of functions,
which we refer to as action functions; alist is an
association list, which we refer to as action alists.
An action function accepts two arguments: the buffer to display and
an action alist. It attempts to display the buffer in some window,
picking or creating a window according to its own criteria. If
successful, it returns the window; otherwise, it returns nil.
See Display Action Functions, for a list of predefined action
functions.
display-buffer works by combining display actions from
several sources, and calling the action functions in turn, until one
of them manages to display the buffer and returns a non-nil
value.
This command makes buffer-or-name appear in some window, without selecting the window or making the buffer current. The argument buffer-or-name must be a buffer or the name of an existing buffer. The return value is the window chosen to display the buffer.
The optional argument action, if non-
nil, should normally be a display action (described above).display-bufferbuilds a list of action functions and an action alist, by consolidating display actions from the following sources (in order):
- The variable
display-buffer-overriding-action.- The user option
display-buffer-alist.- The action argument.
- The user option
display-buffer-base-action.- The constant
display-buffer-fallback-action.Each action function is called in turn, passing the buffer as the first argument and the combined action alist as the second argument, until one of the functions returns non-
nil. The caller can pass(allow-no-window . t)as an element of the action alist to indicate its readiness to handle the case of not displaying the buffer in a window.The argument action can also have a non-
nil, non-list value. This has the special meaning that the buffer should be displayed in a window other than the selected one, even if the selected window is already displaying it. If called interactively with a prefix argument, action ist.The optional argument frame, if non-
nil, specifies which frames to check when deciding whether the buffer is already displayed. It is equivalent to adding an element(reusable-frames .frame)to the action alist of action. See Display Action Functions.
The value of this variable should be a display action, which is treated with the highest priority by
display-buffer. The default value is empty, i.e.,(nil . nil).
The value of this option is an alist mapping conditions to display actions. Each condition may be either a regular expression matching a buffer name or a function that takes two arguments: a buffer name and the action argument passed to
display-buffer. If the name of the buffer passed todisplay-buffereither matches a regular expression in this alist or the function specified by a condition returns non-nil, thendisplay-bufferuses the corresponding display action to display the buffer.