From: dblack@...
Date: 2006-04-02T20:51:25+09:00
Subject: Re: Typed Parameters

Hi --

On Sun, 2 Apr 2006, Trans wrote:

>
> dblack@wobblini.net wrote:
>> Hi --
>>
>> On Sun, 2 Apr 2006, Trans wrote:
>>
>>> <blockquote>
>>> It's not actually that practical, and such things end up making your
>>> code very much like C++ and Java.
>>>
>>> Ruby is smarter than that. Ruby can do more than that.
>>>
>>> Think in terms of what your object's required capabilities are instead
>>> of pretending that a class indicator is sufficient for that.
>>> </blockquote>
>>>
>>> While I understand you pointr Austin --obviously where talking Duck
>>> Typing here. But I think it is interesting to condier that this is some
>>> respect antithetical to OOP in general --I mean the reciever _is_ a
>>> specific type. And that reacieve detemine the functionality of the
>>> method call. It is sort of as if you were progamming in a more
>>> traditional functional language and _had_ to specifiy the type of the
>>> first argument, but never the remaining.
>>>
>>>  foofunc(  FooClass foo, clever, smart, stupid )
>>>
>>> instead of
>>>
>>>  foo.foofunc( clever, smart, stupid )
>>
>> It's actually more like this:
>>
>>    foofunc(object_that_responds_to_foofunc, etc.)
>>
>> The fact that an object handles a message does not imply its class.
>> (I'm transliterating 'type' to 'class' as that seems to be what the
>> thread is actually about [as it usually is :-].)
>
> But the class of that object dictates the functionality of that
> message. That's my point --it's class based.  A double dispath makes
> this very clear:

No: the definition of the method dictates the functionality of the
method.  That can vary from one instance to another, even within a
class.  It often doesn't; but because it *can*, one can view the case
where two instances of a class behave the same way as a special case
of the case where they don't.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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