From: nobu.nokada@...
Date: 2002-08-14T08:23:08+09:00
Subject: Re: Is There an Inverse of 'rb_define_method'?

Hi,

At Tue, 13 Aug 2002 02:08:14 +0900,
William Djaja Tjokroaminata wrote:
> Well, I have not digged too deep into the Ruby C source code; however, to
> me the answer for the dynamic arguments should be from C variable number
> of arguments.

It's done at compile time, but not run time.  Only you can be
sure that a method is callable in a particular form, when the
function signature is known exactly.

> I don't know the exact internal of Ruby, but to me, when parsing a Ruby
> script, I guess the "rb_define_method" is called with argc either equal to
> -1 or -2.  Therefore, if I know that all the C functions are derived like
> this, there is no problem for me to call the C functions directly: if all
> are -1, then the function is of the form "func (int argc, VALUE *argc,
> VALUE self)", and if all are -2, then the function is of the form "func
> (VALUE self, VALUE args)".

However, there are many other functions with non-negative
arity, "func(self, arg1)", "func(self, arg1, arg2)" and so on.
To invoke C function corresponding to ruby method, you must
distinguish them, and call_cfunc() does it.

And a user can redefine methods, then the methods don't have
corresponding C functions.

-- 
Nobu Nakada