eberard@ajpo.sei.cmu.edu (Edward Berard) (09/03/89)
A while ago, I posted the results of "the search for object-oriented
metrics." Since then, I have both had requests for more information,
and have become aware of new sources. What follows are some additional
references.
-- Ed Berard
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From my own personal (Edward V. Berard) experience:
At my former company (EVB Software Engineering, Inc.), when we began
to design a series of reusable, object-oriented components, we
wondered if there was a practical upper limit to the number of
operations in the interface to a class. Based on conversations with
Grady Booch, and on our own experience, we were able to say that:
- most classes should have 20, or fewer, operations in their
interfaces, with 24 operations being a practical upper
limit. This does not mean that you cannot have a class with
more than 24 operations in its interface. It just means that
classes this size, or larger, will be exceptional, i.e.,
typically much less than 10% of the total number of classes
in a class library.
- most methods are very small, e.g., very few methods had more
than 40 executable statements, and many involved only 1-3
executable statements.
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I have received some correspondence from Brian Nixon at the Department
of Computer Science, University of Toronto, Ontario, Canada M5S 1A4
(nixon@ai.toronto.edu). Nixon is doing some work with "performance
theory for semantic data model implementations." I have not yet
finished reading all of the technical reports he has sent me, bu they
look interesting.
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Here is an excerpt from a larger article ("Readings in Object-Oriented
Technology") I wrote:
Object-Oriented Metrics
As organizations begin shifting to object-oriented approaches, they
find that some of the ways in which they used to measure things are
less appropriate. People have already begun asking about
object-oriented metrics. Although most work in this area is relatively
new, there are a growing number of references, including:
[Duhl and Damon, 1988]. J. Duhl and C. Damon, "A Performance
Comparison of Object and Relational Databases Using the Sun
Benchmark," OOPSLA '88 Conference Proceedings, Special Issue of
SIGPLAN Notices, Vol. 23, No. 11, November 1988, pp. 153 - 163.
[Hufnagel and Brown, 1989]. S.P. Hufnagel and J.C. Brown, "Performance
Properties of Vertically Partitioned Object-Oriented Systems," IEEE
Transactions on Software Engineering, Vol. 15, No. 8, August 1989, pp.
935 - 946.
[Liberherr and Holland, 1989]. K.J. Liberherr and I.M. Holland,
"Assuring Good Style for Object-Oriented Programs," IEEE Software,
Vol. 6, No. 5, September 1989, pp. 38 - 48.
[Liberherr and Riel, 1988]. K.J. Liberherr and A.J. Riel, "Demeter: a
CASE Study of Software Growth Through Parameterized Classes, "Journal
of Object-Oriented Programming, Vol. 1, No. 3, August/September 1988,
pp. 8 - 22.
-- Edward V. Berard
Berard Software Engineering, Inc.
18620 Mateney Road
Germantown, Maryland 20874
Phone: (301) 353-9652
E-Mail: eberard@ajpo.sei.cmu.edu