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Objectives

In this section a number of metrics are introduced that may be used to establish quantitative measures of object oriented design. Also formal evaluation criteria for these metrics are discussed, which give a guideline for the interpretation of the outcome of applying the metrics to actual designs.

Points to emphasize

  1. object definition -- WMC, DIN, LCO
  2. attributes -- RFC, LCO
  3. communication -- RFC, CBO

Possible difficulties

The formal definition of the metrics and the proofs concerning their behavior under the evaluation criteria given are in itself not very difficult, but may (with respect to the experience of your audience) be somewhat hard to swallow at first sight.

Hints

It needs to be stressed that the metrics discussed are not supported by any empirical validation. Clearly, this is needed to establish their usefulness in actual software development projects.

Questions

  1. What metrics can you think of for object oriented design? What is the intuition underlying these metrics?
  2. What evaluation criteria for metrics can you think of? Are these sufficient for applying such metrics in actual software projects? Explain.
  3. Give a formal definition of the following metric: WMC, DIN. NOC, CBO, RFC, and LCO. Explain their meaning from a software engineering viewpoint.

Comments

This section must be regarded as a starting point for further exploration and research. One can think of incorporating such metrics in a browsing tool. More importantly, however, are empirical results with regard to the validity of these metrics. }