From: Sean O'Dell <sean@...>
Date: 2004-06-07T01:05:14+09:00
Subject: Re: How to ducktype a Hash?

On Sunday 06 June 2004 00:53, George Ogata wrote:
> "Sean O'Dell" <sean@celsoft.com> writes:
> > That's just a confidence issue.  I don't care if the object coming in is
> > broken.  I'm not concerned about catching objects which are implemented
> > improperly; that's actually very rare.  If an object had a signature that
> > said "I am a hash-like object" that would be fine for me.
>
> So if throughout the standard library, all "Hash-like" objects would
> implement a #hashlike? method, that would be fine?  It seems
> unreasonable to me to expect that everything in the standard library
> have a "X_like?" query method (or any other mechanism) for all
> possible behaviours X.  No matter what, you'll probably at some point
> run into a situation where you want just one more method-or-something
> that says that this object has some other behaviour.

Whatever the "interface" description is, that's the rule.  If an object said 
"I am hash-like," that would be a good start.  Everyone wants more, but 
that's not the issue.  I would just like if objects in Ruby could somehow 
describe what they do by simply declaring themselves as being of a certain 
type, or declaring that they implement certain interfaces.

> > Duck typing and checking respond_to? are completely inadequate, and
> > it seems like people argue those points because Ruby offers nothing
> > else and so what are you going to advocate?  It's those two or
> > rolling your own interface identification system, which I think is
> > cheesy; that sort of functionality should come from the framework.
>
> Sorry for being slow, but I have no idea what you're after.  Could you
> give an example of what you'd like to be able to write to achieve what
> you want?

object.implements(:hash_interface)

	Sean O'Dell