Re: Example use of macro to minimize and generalize the code

[Jean Louis <bugs@gnu.support>]

* Michael Heerdegen <michael_heerdegen@web.de> [2021-06-01 03:35]:
> Jean Louis <bugs@gnu.support> writes:
> 
> > [...]
> > That is why `ignore' is there. Ignore is there to suppress the byte
> > compiler warning just as you guessed it.
> >
> > Otherwise:
> >
> > In when-tabulated-id:
> > rcd-cf.el:165:45: Warning: Unused lexical argument `id'
> 
> Sure - but why do you add an argument to that macro that it (or its
> expansion) doesn't use at all?  That's very confusing, it would be
> better to remove the argument.  Or - could the macro be rewritten to not
> ignore that argument?

I would like to improve but I have to understand what you mean. This
is the macro, arguments are table, id and body. I need all of them.

- table is there as I don't want my functions invoked in other tables,
  it could cause havoc;

- ID is necessary;

- functions can be then invoked programmatically and interactively
  with less arguments:

So help me understand...

(defmacro when-tabulated-id (table id &rest body)
  (declare (indent 2) (debug t))
  (ignore id)
  `(if id
       (progn
	 ,@body)
     (if (or (eq ,table 'any)
	     (string-equal ,table rcd-current-table))
	 (let ((id (tabulated-list-get-id)))
	   (if id
	       (progn ,@body)
	     (message "Did not get ID")))
       (message "This function is for table `%s' only" ,table))))

-- 
Jean

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