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Suppose I have a variable newName which is bearing some mode name, e.g. "python-mode". How do I make current buffer of the mode specified by newName?

(progn (let (newName) (setq newName "python-mode") (newName) ;; doesn't work! It doesn't set current buffer's mode to be a python mode. ) )

This also doesn't work:

(set-variable 'major-mode "python-mode")

This question is fundamental - since it is equal to "is it really possible to treat data as code in lisp?"

Edit

@phils

Your solution doesn't work for me. I copy a buffer - and I want the new one to have the same mode as the old one. So I store the mode of the original buffer in the variable. Then try to apply Your solution. It gives error (it's the essence - I omit here the buffer-copying stuff):

(let (sameMode) (setq sameMode major-mode) (funcall (intern sameMode)) )

sameMode stores here mode in the form of "python-mode" (example for python-mode).

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    phils has the answer for you, but as an aside, whatever would make you think you could use strings as functions, especially without funcall? I really recommend reading the documentation for things like this, since it's included with emacs and would have easily answered this question. Guessing how a language works without trying to understand it first is unlikely to give you much success! Commented Sep 24, 2011 at 15:08
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    Adobe: In Lisp, there is a difference of a variable has a string value or an atom value. The function intern converts a string to an atom. In Emacs, the value of major-mode is an atom an thus you should not use intern. Btw. This is exactly as @phils specified in his second example in his answer. Commented Sep 25, 2011 at 16:05
  • @ Lindydancer: You do make things clear! Commented Sep 25, 2011 at 16:29
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    I just got around to checking the elisp definition of an atom (as I would have called it a symbol myself), and I think that's incorrect terminology. intern returns a symbol. An atom is any object which is not a cons cell, and therefore a string is an atom (which you can confirm with the (atom) predicate function). Commented Sep 28, 2011 at 4:10

1 Answer 1

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(let ((mode "python-mode")) (funcall (intern mode)))

or

(let ((mode 'python-mode)) (funcall mode))
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3 Comments

The second is not good for me - for I don't know ahead which mode will be in a variable - so I have my mode in the form "python-mode" (that's just an example - could be some other mode instead). Your first answer solves the problem - thank You so much. So all in all it's true - lisp could treat data as code!
I've updated the question - Your solution doesn't work for me. Can You please improve it?
Nevermind - Lindydancer explained it for me. You were 100% right and made kind of an ideal answer!

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