Re: elisp macros problem

[Lowell Kirsh <lkirsh@cs.ubc.ca>]

Hmmm, I was only trying to use macros because I thought what I was 
trying wasn't possible with functions. Would this be a more appropriate 
approach?

(defun my-add-hook (hook &rest body)
   (add-hook (intern (concat (symbol-name hook) "-mode-hook"))
             `(lambda () ,@body)))

and then call it like:

(my-add-hook 'lisp-interaction
              '(my-translate-paren-types)
              '(imenu-add-to-menubar "Symbols")
              )

This seems a little more verbose with all the quotes, but I guess it 
could be the 'better' approach since it avoids using macros.

Perhaps my macro approach was a crock. The only reason I defended it was 
becuase I thought you meant that creating the my-add-hook functionality 
itself was the crock.

Well, I'm going with functions now, and I'm also going to get back to 
reading Paul Graham's 'On Lisp', the only comprehensive lisp macros book 
I know of (are there others?)

Lowell


David Kastrup wrote:

> Lowell Kirsh <lkirsh@cs.ubc.ca> writes:
> 
> 
>>This still doesn't seem to work. With the following defun and call:
>>
>>(defmacro my-add-hooks (hooks &rest body)
>>   `(dolist (hook ',hooks)
>>      (my-add-hook hook ,@body)))
>>
>>(my-add-hooks (inferior-lisp lisp emacs-lisp lisp-interaction)
>>               (imenu-add-to-menubar "Symbols"))
>>
>>I get the following macroexpansion, which looks correct to me, but
>>doesn't actually do anything:
>>
>>(cl-block-wrapper
>>  (catch (quote --cl-block-nil--)
>>    (let ((--dolist-temp--20870 (quote (inferior-lisp lisp emacs-lisp
>>    lisp-interaction)))
>>          hook)
>>      (while --dolist-temp--20870
>>        (setq hook (car --dolist-temp--20870))
>>        (my-add-hook hook
>>                     (imenu-add-to-menubar "Symbols"))
>>        (setq --dolist-temp--20870 (cdr --dolist-temp--20870)))
>>      nil)))
> 
> 
> That's because my-add-hook is a macro, too, and so you just add stuff
> to hook-mode-hook three times.
> 
> 
>>>Apart from that, I consider this sort of thing a crock.  What are
>>>you hoping to achieve that you would not be better off doing by a
>>>proper function instead of a macro?
> 
> 
> In short, I still consider this sort of thing a crock, since you'd be
> better off using a function instead of a macro.  You are unable to
> comprehend what your macros do, and it shows.  Macros are just not
> sensible for this sort of thing.  Use functions instead.  You'll need
> to use some quotes at the outer level, but you'll understand what
> happens.
> 
> To fix the above, you'd need to write something like
> 
> (defmacro my-add-hooks (hooks &rest body)
>    (dolist (hook hooks)
>       `(my-add-hook ,hook ,@body)))
> 
>