From: Mathieu Bouchard <matju@...>
Date: 2002-01-28T05:04:28+09:00
Subject: Re: Subrange of String subclass => invalid object


On Mon, 28 Jan 2002, Dave Thomas wrote:
> So, I'm thinking that perhaps something to think about in Rite is
> having built-in frozen classes for primitive types, _String, and so
> on. These classes would be no more that value containers: they'd have
> almost no operators. The implementations of String could then be
> expressed in terms of operations on these _Strings (probably by
> delegating to them, rather than subclassing them).

You don't need delegation here. I'm thinking of two solutions:

	class SimpleString
	  # implemented in C
	end
	class String < SimpleString; include HollowString; end

and:

	class String; include HollowString
	  # equivalent of SimpleString in C goes here
	end

the second one is acceptable. you don't need to handle objects of a lesser
String class when you can mix in the whole functionality directly. There
only needs to be a clear semantics of which String class is used where,
and in the SimpleString protocol, the C-based one is the mandated one for
operations like "get substring" and "replace substring by other
substring"; in higher-level parts of the protocol it's different.

I don't know why you could need the first solution above instead of the
second one.

> We could rewrite the whole String class in Ruby just to experiment
> with new behaviors.

This is all very inspiring, but...

Are we in january 2002, or january 2001 ?

anyway, if "we" are going to start somewhere, "we" are better rewriting
the Regexp class and fixing Ruby's scoping of $1,etc., instead of redoing
what's been already done.

________________________________________________________________
Mathieu Bouchard                   http://hostname.2y.net/~matju