From: Sean O'Dell <sean@...>
Date: 2003-11-20T03:06:18+09:00
Subject: Re: "stereotyping" (was: Re: Strong Typing (Re: Managing metadata about attribute types) )<Pine.LNX.4.44.0311171402340.1133-100000@ool-435 5dfae.dyn.optonline.net>

On Wednesday 19 November 2003 05:09 am, Jim Weirich wrote:
> > On Wed, 2003-11-19 at 10:30, Weirich, James wrote:
>
> [... redesign of Ruby class libraries to support abstract IO objects
> elided ...]
>
> An interesting suggestion, but I still feel it still over constrains the
> problem.  For example, what if I had an input only device.  If I include
> the IO module then I am lying about its capabilities, but if I don't
> include IO, then I can't use it in functions that read from IO objects.

Ruby definitely needs a solid, abstract IO interface.

But as to the issue of partially-implemented interfaces, I think they're fine.  
One IO interface is all you need.  If you have an object that is input-only 
and sequential, and the base IO interface allows for more, then your class is 
simply not going to implement them.

Interfaces don't need to be assumed fully-functional.  Just partially 
implement the interface.  Objects of that class simply cannot be passed to 
functions that do random-access IO or output.  Even in strong-typing 
environments like Java and C++, this happens all the time; as humans, we can 
deal with it.  =)

	Sean O'Dell