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From: stt@inmet.inmet.com
Newsgroups: comp.object
Subject: Examples of Multiple Inheritance?
Message-ID: <60700005@inmet>
Date: 3 Dec 90 20:05:00 GMT
Lines: 35
Nf-ID: #N:inmet:60700005:000:1281
Nf-From: inmet.inmet.com!stt    Dec  3 15:05:00 1990


We are looking for a few good examples of multiple inheritance
in the programming language (especially C++) arena (as opposed to OODB,
OOD, OOA arenas)

The examples in Meyer's Eiffel book tend to be used to represent the
equivalent of module interdependence (Modula's IMPORT,
Ada's WITH).  

The examples in SigPlan Notices and elsewhere seem weak
and relatively easily recast using single inheritance or
component structures.

We are looking for an example of a C++ class (or Eiffel, Objective C,
etc.) which is a "true" sub-class of two (or more) parent classes;
that is, it bears the "is-a" relationship to multiple parents.

Our hypothesis is that multiple inheritance can rarely be useful
unless planned for in advance, which seems to defeat the purpose.
If it does require advance planning, then we anticipate that those
situations would be amenable to other structures, perhaps, for example,
a component with a pointer to its enclosing object.

Multiple inheritance seems to add significant overhead to an OOPL even
when not being used in a system, so we are looking for convincing
examples that it's benefits outweigh the cost.

Thanks in advance.

S. Tucker Taft    
Intermetrics, Inc.
733 Concord Avenue
Cambridge, MA  02138

stt@inmet.inmet.com     ...!uunet!inmet!stt


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