Re: class society?

[progers@ajpo.sei.cmu.edu (Pat Rogers)]

In article <5556@gec-mrc.co.uk> paj@gec-mrc.co.uk (Paul Johnson) writes:
>
>
>The nearest thing to a standard across Ada, Eiffel and C++ would be
>the Booch libraries.  Implementations now exist for all three languages
>(although I have heard dire stories about the Ada implementation).

There is a world of difference in the design of the C++ and Ada Booch
components (Ada83, that is :).  The Ada version uses an approach in which
each data type (Bags, Queues, etc.) includes the representation code for
the type -- that is, each form of queue implements a queue, each form of
bag implements a bag, and so on.  Multiply the number of forms by the number
of abstractions and you're talking about a fair amount of code.  The C++ 
version is not designed the same way.  It uses aggregation to share
representations across forms, cutting the code size dramatically.  The hype
surrounding the code reduction from the use of inheritance is just that.  
There's nothing wrong with the approach used by the C++ version -- it is just 
different. There are no "dire problems" with the Ada version that result 
from the language.  I prefer the C++ *design* for various reasons, but it is
mostly not a function of the language.  The Ada83 version could have been 
designed in largely the same manner.   The Ada9X version should exhibit all the 
advantages of the newer (C++) design, as well as the advantages of a newer
language design. (several :) )


Pat Rogers
progers@ajpo.sei.cmu.edu
Team Ada
-- 
Pat Rogers, Team Ada
progers@ajpo.sei.cmu.edu