Re: Need help with macros

[Cecil Westerhof <Cecil@decebal.nl>]

Cecil Westerhof <Cecil@decebal.nl> writes:

> I am trying to make some useful functionality for Gnus. I think that I
> should use a macro for that. I made the following macro (the two message
> statements are just for debugging):
>     (defmacro gnus-group-jump-bind (key-binding group-to-jump-to)
>       (message "#%s#%s#" key-binding      (type-of key-binding))
>       (message "#%s#%s#" group-to-jump-to (type-of group-to-jump-to))
>       (define-key gnus-group-mode-map key-binding
>         (lambda ()
>           (interactive)
>           (gnus-group-jump-to-group group-to-jump-to))))
>
> When calling this with:
>     (gnus-group-jump-bind "vjd" "nndraft:drafts")
>
> In the message buffer it gives:
>     #vjd#string#
>     #nndraft:drafts#string#
>
> And the return value is:
>     (lambda nil (interactive) (gnus-group-jump-to-group group-to-jump-to))
>
> This is the first problem. Outside the macro group-to-jump-to is not
> existing, I need the value of group-to-jump-to not the name itself. How
> do I do this? I tried eval, but that did not work.
>
> But of course I do not want to set the key bindings manually but data
> driven. So I wrote the following function:
>     (defun gnus-group-do-jump-bind ()
>        (dolist (this-jump gnus-group-jump-list)
>          (let ((this-group (second this-jump))
>                (this-key   (concat "vj" (first this-jump))))
>          (gnus-group-jump-bind this-key this-group))))
>
> I defined the used value:
>     (setq gnus-group-jump-list
>           (list
>            '("d" "nndraft:drafts")
>            ))
>
> And call the function:
>     (gnus-group-do-jump-bind)
>
> This gives in the message buffer:
>     #this-key#symbol#
>     #this-group#symbol#
>     Entering debugger...
>
> And the debug output starts with:
>     Debugger entered--Lisp error: (wrong-type-argument arrayp this-key)
>
> I tried to work with symbol-value, but that did not work.
>
> What do I need to do to get this working?

Found it:
    (setq gnus-group-jump-list
          (list
           '("d" "nndraft:drafts")
           ))

    (defmacro gnus-group-jump-bind (key-binding group-to-jump-to)
      `(define-key gnus-group-mode-map ,(symbol-value key-binding)
        (lambda ()
          (interactive)
          (gnus-group-jump-to-group ,(symbol-value group-to-jump-to)))))

    (defun gnus-group-do-jump-bind ()
       (dolist (this-jump gnus-group-jump-list)
         (let ((this-group (second this-jump))
               (this-key   (concat "vj" (first this-jump))))
         (gnus-group-jump-bind this-key this-group))))

    (gnus-group-do-jump-bind)

And this does what I want. A problem could be that:
     (gnus-group-jump-bind "vjd" "nndraft:drafts")

does not work anymore, but just always use variables solves that
'problem'.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof