Coupling

Introduction

Coupling is the degree to which each module depends on other modules; a measure of how closely connected two modules are. We should strive to minimize coupling.

Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion and vice versa.

Tightly coupled modules have the following disadvantages:

• Change in one module might break another module.

• Change in one module usually forces a ripple effect of changes in other modules.

• Reusability decreases as dependency over other modules increases.

• Assembly of modules might require more effort and/or time.

Coupling can be reduced by:

• By hiding inner details and interacting through interfaces.

• Avoid interacting with classes that it can avoid directly dealing with.

Components in a loosely coupled system can be replaced with alternative implementations that provide the same services.