Information Technology Reference
In-Depth Information
• Is the interface easy to navigate?
• How well does to architectural design accommodate the system's objectives,
reduce complexity, and enhance performance?
12.3.3 Object-Oriented Design Metrics
Object-oriented design can be assessed for its complexity, cohesion, and many
other attributes. While some may argue that OO design metrics are not formal
enough, metrics such as those described in this section can provide valuable,
objective insight into the effectiveness of an OO system and its components.
12.3.3.1 Complexity
The complexity of the design of a system most often measures the degree to which
components are related. Component dependence on other data and components by
looking at a top-down profile of the software design allows complexity to be
measured. Complexity in this regard can be measured by counting the number of
entry and exit points in components as well as fan-in and fan-out, which is dis-
cussed in
Sect. 12.3.3.4
.
12.3.3.2 Cohesion
The cohesion of a component measures the extent to which properties within the
component relates to one another. A components processes and properties should
relate to an individual purpose. If cohesion is high, then it is very likely the
component is maintainable and adaptable.
12.3.3.3 Coupling
In object-oriented design software, components may share information by passing
the item between them. This piece of information is then known as a couple.
Coupling measures the amount of these couples being passed between compo-
nents. Minimizing coupling increases component independence, simplifies design,
and enhances re-usability. Components that have a decreased dependence upon
each other are referred to as loosely couple components while highly interde-
pendent ones are called tightly coupled.
