From: matz@... (Yukihiro Matsumoto)
Date: 2003-11-20T04:05:07+09:00
Subject: Re: "stereotyping" (was: Re: Strong Typing (Re: Managing metadata about attribute types)

Hi,

In message "Re: "stereotyping" (was: Re: Strong Typing (Re: Managing metadata about attribute types)"
    on 03/11/20, "Sean O'Dell" <sean@celsoft.com> writes:

|A contract is any interface, and a Ruby class is an interface.  True, a Ruby 
|class isn't the definition of a contract, but any OO class serves the 
|function well enough.  Despite Ruby's flexibility, at any given point, a 
|class implements an interface.  It can be extended or changed, but it 
|definitely describes an interface.

A class has interface; a class can be used as interface (by set of its
methods); but it should not be checked by kind_of? or anything based
on inheritance, just because it hinders flexibility of dynamic typing
so much; remember StringIO or tempfile examples.

|It's just informational.  It's just for the purpose of speeding up development 
|and making the code a little more robust through a good report of what is 
|going wrong when someone passes in an object that can't be used by the 
|method.  It doesn't prove that an object correctly implements an interface, 
|and the object can definitely break the interface, but the facility would be 
|there for programmers who can make use of it.  For those that tend to break 
|interfaces when programming rather than use them properly, there are always 
|QA jobs.  =)

I admit type checking can gain you something, at the cost of
flexibility, which I don't want to pay in Ruby.  If you prefer static
typing to dynamic typing, it's OK, there so many statically typed
languages out there.  Go ahead.

							matz.