Re: defmacro is worse than my neighbours cat

["Lennart Borgman (gmail)" <lennart.borgman@gmail.com>]

Alan Mackenzie wrote:
> '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!!!

Help!

>> 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?

My cleaning ability. I have no idea now why I left it there. Maybe it is
just that I am scared of the byte compiler.

>>          (turn-on-fun (if (symbolp fun-sym)
> 
>>                           (symbol-value
>>                            (intern
>>                             (symbol-name (quote fun-sym))))
> 
> This bit seems crazy.  

Yes. Thanks. ;-)

> .  At least I think it should - it's a bit early at the moment.  ;-) 

Ok, I am looking forward for the rest ...

> 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)
>>        )))
>