Re: Interactive specs of C functions.

[Stefan Monnier <monnier@iro.umontreal.ca>]

>     Indeed.  How 'bout the patch below?
>     -  if (SUBRP (fun))
>     -    {
>     -      string = (unsigned char *) XSUBR (fun)->prompt;
>     -      if (!string)
>     -	{
>     -	lose:
>     -	  wrong_type_argument (Qcommandp, function);
>     -	}

> That would be a slowdown in very important cases.

Finteractive_form takes an absolutely negligible amount of time.  So I have
no idea what you mean by "a slowdown".  The only "problem" I could imagine
is that Finteractive_form allocates a Lisp string whereas the above code
doesn't.  It's easy to work around it: make an `interactive_form' function
(used by Finteractive_form') which takes an additional char** argument into
which it can return the C string so as to avoid allocating the Lisp string
when called from Fcall_interactively.

> It would be better to keep that code, but have it fall through when it
> doesn't find an interactive string in the special way, into the
> general case.

That would prevent overriding a pre-existing interactive form.


        Stefan