[Zope-dev] Re: ZMI / JavaScript brainstorm

Thu, 18 Apr 2002 20:39:07 +0200

>>>>> "Chris" == Chris Withers <chrisw@nipltd.com> writes:


    > Well, is there any way I can easily tell emacs:

    > - If a file starts with <html> or <!DOCTYPE, then go into
    > html-mode

    > - If a file starts with #, then go into python mode?

    Asking "is it possibile in Emacs..." ?
    You are joking!

    I did my last lisp programming 10 years ago, but thanks to the
    power of (e)lisp and the wonderful documentation of Emacs I came
    up with the following stuff, that you can put in your init file
    (.emacs)

;;; hook to change a buffer mode depending on the first buffer's chars.
(defun foo () "foo fun"
  (interactive "")		; so you can do M-x foo to test it
  (save-excursion	      	; come back to current point after execution
    (goto-char 0)			; go to buffer start
    (cond  ((looking-at "##")		; are we matching pattern ?
	    (python-mode))		; set mode!
	   ((looking-at "<html>")
	    (html-mode)))))

(remove-hook 'find-file-hooks 'foo)	; remove old hook (if any)
(add-hook 'find-file-hooks 'foo t)	; install this one (at the end)

   
    It works like this:

    1) whenever Emacs loads a file, it calls (at the end) the
       functions listed (registered) in find-file-hooks,

    2) we register (add-hook) our function (foo) at the end (last
       param) of that list,

    3) foo is defined with defun ..., it has no params (()), its doc
       string is "foo fun", and can be called interactively (not
       really needed), 

    4) foo is very simple, "cond" is the lisp version of a "case",
       looking-at returns true if text after point matches regular the
       given regexp adn in that case, "cond" evaluate the expression
       that follows. 


	That's all. It is really an hack, but it works for simple
	cases. If you need something "a little" more elaborate let me
	know. For a "real solution" aks the same question on some
	emacs newsgroups. 

	Regards, Luca.