From: Alan Mackenzie <acm@muc.de>
To: "Lennart Borgman \(gmail\)" <lennart.borgman@gmail.com>
Cc: "help-gnu-emacs@gnu.org" <help-gnu-emacs@gnu.org>
Subject: Re: defmacro is worse than my neighbours cat
Date: Fri, 12 Sep 2008 23:10:49 +0000 [thread overview]
Message-ID: <20080912231049.GB1075@muc.de> (raw)
In-Reply-To: <48CADB66.3030807@gmail.com>
'Morning, Lennart!
On Fri, Sep 12, 2008 at 11:13:10PM +0200, Lennart Borgman (gmail) wrote:
> defmacro is worse than my neighbour's cat.
Miaow!!!
> When I think I everything is fine and I calm down they bite.
> I have a defmacro where I define a function and I want to build the doc
> string for this function in a certain way. This works fine - until I
> byte compile it. Can someone please try to explain to me how I can do
> what I want?
> Below is the defmacro. Look for "fix-me".
> (defmacro define-mumamo-multi-major-mode (fun-sym spec-doc chunks)
> "Define a function that turn on support for multiple major modes."
> (let* ((mumamo-describe-chunks (make-symbol "mumamo-describe-chunks"))
OK, here's a problem. You have _two_ symbols called
"mumamo-describe-chunks" here. One (uninterned) is the value of the
other. Why do this? Why not just declare the symbol directly inside the
let* form and use it?
You really don't need to use make-symbol at all, unless you deliberately
want it uninterned, or you're making up the name as you go along. You
can simply write
(let* mumamo-describe-chunks
> (turn-on-fun (if (symbolp fun-sym)
> (symbol-value
> (intern
> (symbol-name (quote fun-sym))))
This bit seems crazy.
(symbol-name (quote fun-sym))
is easier to read as
(symbol-name 'fun-sym)
which is "fun-sym". You then "intern" it (i.e. get the (existing)
'fun-sym) and then take the value of 'fun-sym with `symbol-value'.
You don't need this. You know that (the value of) fun-sym is a symbol,
so these three lines are entirely equivalent to
fun-sym
. ;-)
> (error "Parameter FUN-SYM must be a symbol")))
> (turn-on-fun-alias (intern
> (concat "mumamo-alias-"
> (symbol-name
> (symbol-value
> (intern
> (symbol-name (quote fun-sym))))))))
Here you've got one sensible use of intern, and one silly one. This
should just say:
(turn-on-fun-alias (intern (concat "mumamo-alias-" fun-sym)))
. At least I think it should - it's a bit early at the moment. ;-)
I've got to get to bed, so I can't look at the rest right now.
> (turn-on-hook (intern (concat (symbol-name turn-on-fun) "-hook")))
> (turn-on-map (intern (concat (symbol-name turn-on-fun) "-map")))
> (turn-on-hook-doc (concat "Hook run at the very end of `"
> (symbol-name turn-on-fun) "'."))
> (chunks2 (if (symbolp chunks)
> (symbol-value chunks)
> chunks))
> (docstring
> (concat
> spec-doc
> "
> This function is called a multi major mode. The main use for it
> is in `auto-mode-alist' to have Emacs do this setup whenever you
> open a file named in a certain way. \(You can of course call
> this function directly yourself too.)
> It sets up for multiple mode in the following way:
> "
> ;; Fix-me: During byte compilation the next line is not
> ;; expanded as I thought because the functions in CHUNK is
> ;; not defined. How do I fix this?
> (funcall 'mumamo-describe-chunks chunks2)
> "
> At the very end this multi major mode function runs first the hook
> `mumamo-turn-on-hook' and then `" (symbol-name turn-on-hook) "'.
> There is a keymap specific to this multi major mode, but it is
> not returned by `current-local-map' which returns the chunk's
> major mode's local keymap.
> The keymap is named `" (symbol-name turn-on-map) "'.
> This major mode has an alias `mumamo-alias-"
> (symbol-name turn-on-fun) "'.
> For more information see `define-mumamo-multi-major-mode'."
> )))
> `(progn
> (add-to-list 'mumamo-defined-turn-on-functions (cons (car
> ',chunks2) ',turn-on-fun))
> (defvar ,turn-on-hook nil ,turn-on-hook-doc)
> (defvar ,turn-on-map (make-sparse-keymap)
> ,(concat "Keymap for multi major mode function `"
> (symbol-name turn-on-fun) "'"))
> (defvar ,turn-on-fun nil)
> (make-variable-buffer-local ',turn-on-fun)
> (put ',turn-on-fun 'permanent-local t)
> (defun ,turn-on-fun nil ,docstring
> (interactive)
> (let ((old-major-mode (or mumamo-major-mode
> major-mode)))
> (kill-all-local-variables)
> (run-hooks 'change-major-mode-hook)
> (setq mumamo-multi-major-mode ',turn-on-fun)
> (setq ,turn-on-fun t)
> (mumamo-add-multi-keymap ',turn-on-fun ,turn-on-map)
> (setq mumamo-current-chunk-family (copy-tree ',chunks2))
> (mumamo-turn-on-actions old-major-mode)
> (run-hooks ',turn-on-hook)))
> (defalias ',turn-on-fun-alias ',turn-on-fun)
> )))
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2008-09-12 23:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-12 21:13 defmacro is worse than my neighbours cat Lennart Borgman (gmail)
2008-09-12 23:10 ` Alan Mackenzie [this message]
2008-09-12 23:33 ` Lennart Borgman (gmail)
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