From: Robert Dober <robert.dober@...>
Date: 2008-07-21T23:22:38+09:00
Subject: Re: protected members or explicit abstract classes?

On Mon, Jul 21, 2008 at 2:37 PM, David A. Black <dblack@rubypal.com> wrote:
> Hi --
> For true duck typing you would just do:
>
>  s.the_method
In the general case thats seems clumsy to me, I'd rather check if a
protocol is implemented. A very simple example is an IOArray I use to
capture output, it mocks two file methods #puts and #<<.
What would you prefer?

raise Whatever unless o.replies_to?( :puts ) && o.replies_to?( :<< )

raise Whatever unless o.implements_behavior? IOArray # but the name is bad

Now imagine the protocol has five or even 10 methods?

Maybe it might also be helpful to recall the definition of duck
typing: "If it walks like a duck and talks like a talk...", this is
about behavior and not about methods.
My journey - that was long and would not have been so productive were
it not for this list - has brought me to search out for new
expressiveness of behavior and I pretty much like traits most right
now. But I am still open to
walk on ;).


Cheers
Robert
-- 
http://ruby-smalltalk.blogspot.com/

There's no one thing that's true. It's all true.
--
Ernest Hemingway