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2.2 Getting Buffers

The buffer-name function returns the name of the buffer; to get the buffer itself, a different function is needed: the current-buffer function. If you use this function in code, what you get is the buffer itself.

A name and the object or entity to which the name refers are different from each other. You are not your name. You are a person to whom others refer by name. If you ask to speak to George and someone hands you a card with the letters ‘G’, ‘e’, ‘o’, ‘r’, ‘g’, and ‘e’ written on it, you might be amused, but you would not be satisfied. You do not want to speak to the name, but to the person to whom the name refers. A buffer is similar: the name of the scratch buffer is *scratch*, but the name is not the buffer. To get a buffer itself, you need to use a function such as current-buffer.

However, there is a slight complication: if you evaluate current-buffer in an expression on its own, as we will do here, what you see is a printed representation of the name of the buffer without the contents of the buffer. Emacs works this way for two reasons: the buffer may be thousands of lines long—too long to be conveniently displayed; and, another buffer may have the same contents but a different name, and it is important to distinguish between them.

Here is an expression containing the function:

     (current-buffer)

If you evaluate this expression in Info in Emacs in the usual way, #<buffer *info*> will appear in the echo area. The special format indicates that the buffer itself is being returned, rather than just its name.

Incidentally, while you can type a number or symbol into a program, you cannot do that with the printed representation of a buffer: the only way to get a buffer itself is with a function such as current-buffer.

A related function is other-buffer. This returns the most recently selected buffer other than the one you are in currently, not a printed representation of its name. If you have recently switched back and forth from the *scratch* buffer, other-buffer will return that buffer.

You can see this by evaluating the expression:

     (other-buffer)

You should see #<buffer *scratch*> appear in the echo area, or the name of whatever other buffer you switched back from most recently1.


Footnotes

[1] Actually, by default, if the buffer from which you just switched is visible to you in another window, other-buffer will choose the most recent buffer that you cannot see; this is a subtlety that I often forget.