From: Paul Brannan <pbrannan@...>
Date: 2005-10-20T22:38:24+09:00
Subject: Re: Method annotation and anonymous functions

On Thu, Oct 20, 2005 at 09:40:21AM +0900, David A. Black wrote:
> I think I'm coming from a different perspective.  I haven't seen any
> examples of this that make me think it's worth either incompatibility
> or new punctuation.  I strongly dislike the idea of having a
> specification of the class of the return value (object) of a method,
> since that militates against duck typing.  But maybe that's just an
> example.

It's useful for documentation.

I like that ri Array#+ tells me that + returns an array.  If ri told me
that it returned an object that supports the [] and []= operations, I
would possibly convert the return value to an array before using it.

IMO what a method expects from the user should be as minimal as
possible, to make the method as reuseable as possible, but what the user
can expect from a method (both what the method does and what it returns)
should be very precisely specified.  If the type or meaning of the
return value of a method changes, there will often be an
incompatibility; such changes should be made with caution.

Paul