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27.9 Creating Buffers

This section describes the two primitives for creating buffers. get-buffer-create creates a buffer if it finds no existing buffer with the specified name; generate-new-buffer always creates a new buffer and gives it a unique name.

Other functions you can use to create buffers include with-output-to-temp-buffer (see Temporary Displays) and create-file-buffer (see Visiting Files). Starting a subprocess can also create a buffer (see Processes).

— Function: get-buffer-create buffer-or-name

This function returns a buffer named buffer-or-name. The buffer returned does not become the current buffer—this function does not change which buffer is current.

buffer-or-name must be either a string or an existing buffer. If it is a string and a live buffer with that name already exists, get-buffer-create returns that buffer. If no such buffer exists, it creates a new buffer. If buffer-or-name is a buffer instead of a string, it is returned as given, even if it is dead. 

          (get-buffer-create "foo")
               ⇒ #<buffer foo>

The major mode for a newly created buffer is set to Fundamental mode. (The default value of the variable major-mode is handled at a higher level; see Auto Major Mode.) If the name begins with a space, the buffer initially disables undo information recording (see Undo).

— Function: generate-new-buffer name

This function returns a newly created, empty buffer, but does not make it current. The name of the buffer is generated by passing name to the function generate-new-buffer-name (see Buffer Names). Thus, if there is no buffer named name, then that is the name of the new buffer; if that name is in use, a suffix of the form ‘<n>’, where n is an integer, is appended to name.

An error is signaled if name is not a string. 

          (generate-new-buffer "bar")
               ⇒ #<buffer bar>
          (generate-new-buffer "bar")
               ⇒ #<buffer bar<2>>
          (generate-new-buffer "bar")
               ⇒ #<buffer bar<3>>

The major mode for the new buffer is set to Fundamental mode. The default value of the variable major-mode is handled at a higher level. See Auto Major Mode.