Class Oriented Metrics - MOOD Metrics Suite

The MOOD metrics set refers to a basic structural mechanism of the OO paradigm as encapsulation (MHF and AHF), inheritance (MIF and AIF), polymorphisms (PF), message-passing (CF) and are expressed as quotients. The set includes the following metrics:

- Method Hiding Factor (MHF)
MHF is defined as the ratio of the sum of the invisibilities of all methods defined in all classes to the total number of methods defined in the system under consideration. The invisibility of a method is the percentage of the total classes from which this method is not visible. A low MHF indicates insufficiently abstracted implementation. A large proportion of methods are unprotected and the probability of errors is high. A high MHF indicates very little functionality. It may also indicate that the design includes a high proportion of specialized methods that are not available for reuse. An acceptable MHF range of 8% to 25% has been suggested but we neither endorse or criticize this view.
note : inherited methods not considered.
- Attribute Hiding Factor (AHF)
AHF is defined as the ratio of the sum of the invisibilities of all attributes defined in all classes to the total number of attributes defined in the system under consideration.
- Method Inheritance Factor (MIF)
MIF is defined as the ratio of the sum of the inherited methods in all classes of the system under consideration to the total number of available methods (locally defined plus inherited) for all classes.
- Attribute Inheritance Factor (AIF)
AIF is defined as the ratio of the sum of inherited attributes in all classes of the system under consideration to the total number of available attributes
(locally defined plus inherited) for all classes.
- Polymorphism Factor (PF)
It measures the degree of method overriding in the class inheritance tree. It equals the number of actual method overrides divided by the maximum number of possible method overrides.
PF = overrides / sum for each class(new methods * descendants)
PF varies between 0% and 100%. As mentioned above, when PF=100%, all methods are overridden in all derived classes. A PF value of 0% may indicate one of the following cases:
* project uses no classes or inheritance.
* project uses no polymorphism.
* full class hierarchies have not been analyzed.
- Coupling Factor (CF)
CF is defined as the ratio of the maximum possible number of couplings in the system to the actual number of couplings not imputable to inheritance.
CF = Actual couplings/Maximum possible couplings