D - more power than (really) needed !

[Lars Ivar Igesund]

Don Clugston wrote:

> Hasan Aljudy wrote:
>> David Medlock wrote:
>> <snip>
>>> see:
>>> http://okmij.org/ftp/Computation/Subtyping/#Problem
>>>
>>> -DavidM
>> 
>> A nice example of not understanding OOP :)
>> 
>> WOW .. I think I'm beginning to understand what Schock means when he
>> says everyone out there thinks they are doing object oriented
>> programming, but only very few of them really are.
>> 
>> There's no "book" that you can follow literally to produce good code.
>> It's a matter of trial and error. You try to subclass CSet from CBag,
>> and disvocer that it doesn't work, or produce more problem than it
>> solves, then don't whine about it, just implement CSet differently. It's
>> not OOP's fault, nor is it inheritance's fault.
> 
> I disagree, I think this is absolutely OOP's fault. 'Trial and error'
> seems to be a fundamental feature of OOP. If you use OOP, you are
> committing yourself to continually restructuring your code. (OOP is the
> worst thing that ever happenned to code reuse!)
> 
>> If you try to open a door with a screw-driver and it doesn't work,
>> should you blame the screw-driver, or blame yourself for not
>> understanding how doors work?
>> 
>> Apparently subclassing CSet from CBag wasn't such a good idea. Don't
>> blame the object oriented paradigm for it. No where in the paradigm does
>> it say that you should sublcass CSet from CBag!
> 
> And this is the problem. It gives no guidance for when you should use
> subclassing. That turns out to be a fantastically difficult problem, and
> OOP just glossed over it.
> 
> Fundamentally, I think the fatal flaw in OOP is that "is-a"
> relationships do not exist. (Well, _maybe_ for abstract geometrical
> shapes, but definitely not for anything useful). The text book examples
> are wrong: a 'Manager' is NOT a type of 'Employee'. An 'Employee' is NOT
> a type of 'Person'. Actually, 'Object' works as a base class, because
> every object really IS-A block of bytes in RAM, some of which are
> organised into a virtual function table. But note that it's not some
> kind of abstract Platonic entity. It's a bunch of transistors.
> 
> In OOP, you spend your time trying to find Is-A relationships, but they
> don't exist. Unsurprisingly, hardly anyone is "really" doing OOP. It
> seems to be unimplementable.

It might have been this way, but newer OOP books actually prefers has-a
relationships before is-a.