Schaum's Outline Series

192
class Md Mi Ad Ai
A x(),y() none a none
B w(),z(),y() A::x() b,bb A::a
C v() B::w(),z(),y c B::bb
12.3.3 COUPLING FACTOR
CHAPTER 12 Object-Oriented Metrics
A::x()
MIF ¼ 5=11 AIF ¼ 2=6
The coupling factor (CF) measures the coupling between classes excluding coupling
due to inheritance.
Let is_client(c i,c jÞ¼1 if class i has a relation with class j; otherwise, it is zero.
The relation might be that class i calls a method in class j or has a reference to class
j or to an attribute in class j. This relationship cannot be inheritance.
CF ¼
XTC XTC i¼1
j¼1
is_clientðc i; c jÞ
TC 2 TC
EXAMPLE 12.4
Calculate the coupling factor on the object model shown in Fig. 12-3 for the bedand-breakfast
problem (Problem 11.4). Onlyassume a relationship if it is required
bythe associations shown on the diagram.
1
1
B&B
1
1
1..n
1..n
0..n
0..n
calendar bedroom customer
transaction
1
0..n
1
0..n 0..n
reservation
1
Fig. 12-3
payment expense