Re: defining many similar functions using macros

[Daniel Pittman]

On 3 Oct 2004, Joe Corneli wrote:
> I have a lot of functions that are very similar:
>
> (defun tex-alpha ()
>   (interactive)
>   (insert "\\alpha"))
>
> (defun tex-beta ()
>   (interactive)
>   (insert "\\beta"))
>
> ...
>
> I would like to define them all in one go:

[...]

> This seems like a good chance to use a macro.  My first experiment
> along these lines fails however, and I could use some help
> re-designing it.
>
> This macro works on single elements:

[...]

> triggers an error:

[... when run from `dolist' ...]

> Debugger entered--Lisp error: (wrong-type-argument sequencep elt)
> concat("tex-" elt)
> (intern (concat "tex-" name))
> (list (quote defun) (intern (concat "tex-" name)) nil (quote (interactive))
>       (list (quote insert) "\\" name))
> ...
>
> There seem to be some subtleties associated with macro expansion
> that I'm missing here.  Help would be appreciated.

Indeed.  The solution suggested elsewhere in the thread makes the macro
expansion work as expected, but why bother with that hoop - just write
the code directly:

(dolist (name '("alpha" "beta"))
  (fset (intern (concat "tex-" name))
        `(lambda () (interactive) (insert "\\" ,name))))

Note the backquote is needed to use the value of name, rather than the
symbol, but that cuts out the macro expansion middle-man nicely.

        Daniel
-- 
We live in a hallucination of our own devising.
        -- Alan Kay