From: David Landrith <dlandrith@...>
Date: 2003-03-25T12:50:08+09:00
Subject: Re: Writing a new method in C for a subclass

> If you're trying to do something very deep, which involves fudging 
> with the
> implementation of Array itself, rather than just adding methods to 
> Array,
> then I'm out of my depth :-)
>
> It does seem to me that whatever you write is going to be heavily tied 
> to
> the particular implementation of Array which exists now, and therefore 
> may
> not be very portable. Without knowing what you're trying to achieve, 
> would
> be it be worth using 'has_a' instead of 'is_a'? That is, create a new 
> object
> which in turn contains an instance of an Array? You can then 
> mechanically
> delegate to it.

I'm not sure that what I am trying to do is very complicated, and I 
certainly don't want to tie it to any specific implementation of Array.

I know that I'm not doing a great job of explaining this, but I have 
not sensed that there is a specific lingo that I am supposed to be 
using to describe how the C extension API works with any real 
granularity.  If I am wrong about this, I'd like a few pointers on 
where to look to become more familiar with it.

At any rate, let my try to explain again:

If I want to make a new Array in c, I can type rb_ary_new2(long int) -- 
or rb_ary_new() which calls it -- in my c program/extension, and one 
may look at implementation of these methods in array.c.  So suppose I 
want to create a class that extends Array then instantiate it in c.  If 
I do this, then I must have a function -- say myArray_new() -- in C 
that wraps up a structure and returns a pointer to it much like 
rb_ary_new2(long int).   Are there any special requirements for 
myArray_new to make sure that it's values are accessible by the methods 
of its superclass?  Do I need to somehow include a pointer the the 
rb_cArray object or the RArray struct in the struct used by myArray?  
Or do I simply make a struct for myArray that is a superset of the 
values in the RArray struct and let the "define_class" method handle 
the details?

Does this make sense?

-------------------------------------------------------
David King Landrith
   (w) 617.227.4469x213
   (h) 617.696.7133

One useless man is a disgrace, two
are called a law firm, and three or more
become a congress   -- John Adams
-------------------------------------------------------
public key available upon request