Inheritance: Interface vs Implementation (was: Questions on inheritance) 
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 Inheritance: Interface vs Implementation (was: Questions on inheritance)

Quote:




> >>   Er...  What's the difference between "subtype" and "subclass"?

> >A subclass is built to inherit code and to describe objects in terms
> >of (from the code reuse point of view) similar objects.
> >Types describe compatibility and interfaces.

>   That's interesting.  So really, the class heirarchy is an implementation
> issue, while the type heirarchy is an interface issue?

> >Most languages having both static types and classes use classes for
> >both subtyping and subclassing as both need similar mechanisms.
> >There are languages which allow to distinguish this aspect, and even
> >in C++ you may derive a subclass from a class which is not a subtype.
> >In other words, it inherits code, but its instances are not type
> >compatible with instances of the superclass.

>   Are you referring to C++'s private inheritance?  There's another
> question I have: how is this feature useful?  I've never used it.  Maybe
> I'm missing out on something.

>   To me it seems like it's in the "wrong direction".  In other words, it
> allows you to create a subclass that is not a subtype, while it is far
> more useful to create a subtype that is not a subclass.  That is, is
> it not more useful to be able to pass two unrelated classes to the
> same function and make use of their similarities, than it is to simply
> declare that a subclass (which would otherwise be a subtype) is not
> a subtype?

>  -PD

This whole "dialog" is such an obviously manufactured desperate last
breath attempt by the Smalltalk community...but...there's not much to
argue with.
....Mike

- Show quoted text -

Quote:
> Patrick Doyle




Thu, 14 Oct 1999 03:00:00 GMT  
 Inheritance: Interface vs Implementation (was: Questions on inheritance)

Quote:

> This whole "dialog" is such an obviously manufactured desperate last
> breath attempt by the Smalltalk community

Huh? Why would it need to do that? The "Smalltalk community" is doing
just fine.

o IBM's Smalltalk sales grew 225% last year (and it looks like they will
do *much* better this year). I have been told that they sold over 5000
copies of VA for Smalltalk in January alone!

o IBM is about to release VA 4.0 - the most advanced Smalltalk
development environment ever (and one of the most advanced software
development environments available anywhere).

o Gemstone's Smalltalk sales grew 250% last year.

o Tens of thousands of people have downloaded Smalltalk Express and have
started learning Smalltalk.

o Traffic is considerably higher in comp.lang.smalltalk than it was a
year ago.

o Last year several excellent new Smalltalk-related books were released.

o There are several new Windows 95/NT Smalltalk compilers on the market
(or soon to be released).

My conclusion is that Smalltalk will survive just fine as it always has.

-Eric Clayberg

Smalltalk Systems (StS)         http://www.smalltalksystems.com
An Instantiations Company       http://www.instantiations.com



Thu, 14 Oct 1999 03:00:00 GMT  
 Inheritance: Interface vs Implementation (was: Questions on inheritance)

Quote:


> > This whole "dialog" is such an obviously manufactured desperate last
> > breath attempt by the Smalltalk community

> Huh? Why would it need to do that? The "Smalltalk community" is doing
> just fine.

I was trying to be sarcastic but can see that it's not very appearent.
Sorry for the confusuion.
....Mike


Thu, 14 Oct 1999 03:00:00 GMT  
 Inheritance: Interface vs Implementation (was: Questions on inheritance)

:
: My conclusion is that Smalltalk will survive just fine as it always has.

I sure hope so.  Smalltalk and CLOS are among the most powerfully fun
languages I've had the great pleasure to become acquainted with.

Elliott



Fri, 15 Oct 1999 03:00:00 GMT  
 Inheritance: Interface vs Implementation (was: Questions on inheritance)



Quote:

>This whole "dialog" is such an obviously manufactured desperate last
>breath attempt by the Smalltalk community...but...there's not much to
>argue with.

  Huh?  First of all, I've never used Smalltalk in my life.  Second, what
exactly were you trying to say in that incoherent sentence?  I can't make
any sense of it.

 -PD
--
--
Patrick Doyle



Sat, 16 Oct 1999 03:00:00 GMT  
 
 [ 5 post ] 

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