From: Sean O'Dell <sean@...>
Date: 2004-06-06T02:30:47+09:00
Subject: Re: How to ducktype a Hash?

On Saturday 05 June 2004 02:28, Robert Klemme wrote:
> Maybe I got something wrong here, but I thought the idea of duck typing was
> to just use the instance as a hash and get bitten if it's not.  After all,
> either way an exception will be thrown.  If you don't throw an exception
> you can still catch NoSuchMethodEx and treat it appropriately.

The problem isn't that the object doesn't respond to the methods I need, it's 
that it DOES respond to the methods I need, but the methods don't do what I 
expect them to do.  In this case, duck-typing simply doesn't work for me.  I 
found this error through duck-typing, but it existed for weeks before I 
realized that some objects were quietly trashing sections of data I was 
passing around, because strings, arrays and others all respond to [] and []=, 
but DON'T contain objects quite the same way hashes do.

I just don't like this duck-typing business.  I can handle dynamic typing, but 
I wish there were something more solid about the typing, at least a way to 
know when an object implements a certain interface or not, so I can tell an 
array-like object from a hash-like object.

	Sean O'Dell