Coupling and Cohesion

Let’s understand what coupling and cohesion are and how they factor in the maintainability of any system.

Coupling

Coupling is the measure of dependency between modules/components. In other words, it is the degree of interdependence between two modules/components. Two modules/components would be considered interdependent if a change in one requires a change in the other.

Measuring coupling

The degree of coupling between modules is determined by the following:

• The number of interfaces between modules (quantity)
• The complexity of each interface (determined by the type of communication) (quality)

Why is a high degree of coupling bad?

A high degree of coupling between two modules would mean strong interconnections between the modules. This means that the modules would have a high dependence on one another. This would result in a system where the modules are difficult to build, test, reuse, and understand. The system would therefore be difficult to ...