1. Measurement - part 5 1 An Evaluation of the MOOD Set of Object-Oriented Software Metrics Harrison, Counsell and Nithi IEEE Trans on Soft Eng June 1998

2. Measurement - part 5 2 Criteria for Valid Metrics u 1. Must allow different entities to be distinguished u 2. Must obey representation condition u 3. Each unit of attribute contributing to a valid metric is equivalent u 4. Different entities can have the same attribute value

3. Measurement - part 5 3 types of measurement u direct –does not depend on other measures u indirect –involves one or more other measures –e.g. density

4. Measurement - part 5 4 Indirect metrics u 1. Explicitly defined model u 2. Model must be dimensionally consistent u 3. No unexpected discontinuities u 4. Units and scale types must be correct

5. Measurement - part 5 5 Encapsulation u MHF - Method Hiding Factor u AHF - Attribute Hiding Factor u Proposed as “measures of encapsulation” u Earlier as measures of “the use of information hiding concept”

6. Measurement - part 5 6 Terms u Data encapsulation - “power of the a language to hide implementation detail …, the separation of interface from implementation, the use of opaque types” u Information Hiding - “the visibility of methods and/or attributes to other code”

7. Measurement - part 5 7 Question u Why do the authors have the encapsulation vs information hiding vs visibility discussion?

8. Measurement - part 5 8 Visibility u Is_visible(M,C) –1 iff class C may call method M and M is in another class –0 otherwise u V(M) = sum of Is_visible for method M over all classes divided by number of other classes –percentage of other classes that can call this method

9. Measurement - part 5 9 MHF definition u Summation over all methods in all classes of 1 minus the V(M) divided by the total number of methods

10. Measurement - part 5 10 Theoretical Validation u According to the authors, is the MHF measure theoretically validated? u Would I agree? Why or why not?

11. Measurement - part 5 11 Model for MHF? u What would be a good model? u Empirical Relationship? u Scale Type?