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From: jhd@herold.franken.de (Joachim Durchholz)
Subject: Re: OO, C++, and something much better!
Date: 1997/01/24
Message-ID: <6PUKuJvV3RB@herold.franken.de>#1/1
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references: <JSA.97Jan16141937@alexandria>
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 comp.lang.eiffel,comp.lang.ada,comp.lang.c++,comp.lang.smalltalk,comp.object
Date: 1997-01-24T00:00:00+00:00
List-Id: <comp.lang.ada>


Tansel wrote:

> Contrary to what people say, type checking is against the nature of
> object oriented systems development. Remember, in OO, we only care about
> the interface of the other object. In fact it should be an OO sin to ask
> the type, because, in theory, we don�t want to get intimate with objects
> we are interacting apart from their interface. We only want to know the
> interface.

There's a misunderstanding here.

I agree checking should be done on the interface, but I was not aware of  
any difference between type and interface. After all, objects with  
identical interface have the same type for all practical purposes.

> ATD based languages because of language structure. In languages such as
> Smalltalk, on the other hand, even knowing the type of an object is not
> a guarantee that this object will answer a method that we use, because
> we can really delete any method for that object while the system is in
> operation, so even type checking is not a perfect solution.

A good type-checking Smalltalk system could work with versioning, so if  
you delete a routine, you actually define a new class with the routine  
deleted. Existing (typechecked) code would continue to work. Of course the  
system should convert as much as possible to the new version of the class  
structure, but if it finds code that uses the delete routine, the  
programmer has to correct it (or the code has to remain on the old version  
level).

> Disadvantages? Many.

Thanks for the info. This type of stuff is tremendous help in seeing  
beyond all the hype.

> For starters, most Smalltalks and their tools are ridiculously
> expensive. This is equivalent for the vendors to shooting themselves in
> the foot, at the same time hitting us with the richocet.

Seems to be a general problem. Obviously this is one of the worst market  
barriers for new languages: Market is small, so prices have to be high to  
make a living from them, so market remains small.
On the other hand, this has saved us from countless language wars, so  
maybe this vicious circle is a godsend...

> Why don't you come to Smalltalk Solutions 97? You may see many examples.
> It is in NY at Marriot Marquis between March 10-13.

Sorry, that's a bit far from Germany... (domain .de is short for  
"Deutschland").

> This is not true. Smalltalk base is growing very strongly especially in
> organizations such as banks.

I didn't want to downplay the growth of Smalltalk. It's just that the  
numbers presented were nearly content-free. I'd very much like to see some  
solid numbers, though.

Regards,
-Joachim

--
Joachim Durchholz, Hans-Herold-Str. 25, D-91074 Herzogenaurach, GERMANY