Re: Arbitrary function: find the number(s) of expected arguments

[Michael Heerdegen <michael_heerdegen@web.de>]

Eli Zaretskii <eliz@gnu.org> writes:

> Thanks.  A few comments below.  Let's wait for a few days to give
> others a chance to comment.

That approach will reveal the (0 . many) problem as we discussed, e.g.


  (defun f (x y) x)

  (advice-add 'f :filter-return #'identity)

  (func-arity 'f)

  (0 . many)


So, to the question "can I call function X with that many args", the
answer can be "maybe".  In that case, the situation is not better than
now.  Since you know the answer not before run-time, this doesn't solve
the problem in the bug report, because you still have to write
alternative code for the "maybe" case - every time.

Don't take me wrong: this patch can be useful, e.g. for generating help
pages.  But IMO it isn't useful for coding.  On the contrary, I think
advertising `func-arity' to the user with this name will lead to a lot
of erroneous code.


Michael.