Re: Interesting but sensitive topic to discuss (HELP: - OOP and CASE tools)

[rmartin@oma.com (Robert C. Martin)]

In article <328109CD.6685@concentric.net>, Alan Lovejoy
<alovejoy@concentric.net> wrote:

> The architecture and design of a program is a function of what
**objects** it contains and 
> how they interact. 

I disagree.  The architecture of a program is a function of the way
it manages to decouple the source code while allowing the interactions
to remain unaffected.  

This is true irrespective of language.  It is as true in Smalltalk as
it is in Java or C++.  Whenever one neglects to manage the static relationships
between source code units, one winds up in trouble.

> Class inheritance is an abstraction mechanism for code sharing.  It has
nothing much to do 
> with architecture or design of a program.  Proof: any program using
class inheritance can
> easily be converted into a completely equivalent program where all the
leaf classes are root
> classes: 

This is truer for Smalltalk than it is for Java or C++.  But it isn't really
even true in Smalltalk.  Consider, that the way your two systems are affected
by a change in specifications is very different.  In the flattened model,
the classes can, and must, be changed independently.  
But in the hierarchical model a change in the middle of a hierarchy affects
all those classes that depend upon it.  Thus, the design of the heirarchy
must take into consideration the most likely changes that will occur; and
should strive to minimize the effort involved in making those changes.

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