From: matz@... (Yukihiro Matsumoto)
Date: 2003-11-20T06:38:21+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:

|> library is requiring Socket interface, but without that kind of
|> interface check, no flexibility is lost, it's little bit hard to find
|> out the semantics.
|
|When a method is written to use the methods of another object, and that code 
|is distributed as a library, the function of that method is fixed.  You must 
|pass it an object that has the methods it requires, and those methods must 
|take the exact parameters it expects.
|
|The flexibility to change the method of the object is lost.  You cannot change 
|the parameters to the "send" method of a Socket object and pass it to a 
|library that uses it.  You will get an error deep inside the library.

I don't understand "the flexibility to change the method of the
object".  What is that?  I think it has never existed before.
We cannot lose something that has never existed.

|> |Reconsider, Matz.
|>
|> Reconsider what?  I didn't tell you any decision yet.  I'm still
|> the level of seeking what you mean.
|
|You said the following:
|
|> I admit type checking can gain you something, at the cost of
|> flexibility, which I don't want to pay in Ruby. 
|
|You don't want to pay the price of type checking in Ruby.  My version of it is 
|really "interface checking," but either way what you said sounds like you've 
|decided you don't want to pay the price for any of this.

You've misunderstood me.  I don't want to pay "the cost of losing
flexibility", that means I don't want to make any change hindersc
"my" flexibility, which can be harmed by "type checking based on
inheritance".  Since your "interface checking" do not affect
"flexibility" in bad manner, I said nothing against it.

But still, there's no known effective way to define and check
"interface" in a language so dynamic as Ruby.  Long way to go.

							matz.