Node:Getting Buffers, Next:Switching Buffers, Previous:Buffer Names, Up:Practicing Evaluation
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 the expression in the usual way, #<buffer *info*>
appears 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. 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.
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.