I had previously written a post related to coupling and cohesion here and that was more of a basic definition of both the terms.
In this post I would like to throw some light on the tight dependency on the type of the component in use. Generally we would aim to design classes such that they interact via the interfaces or more generally put via API. Suppose we use interfaces (more of a generic term where we dont have implementations, not specific to keyword interface in Java or C#), but this is not enough, we need to provide some kind of implementation for the interface which is actually consumed by the other client classes.
Cohesion and Coupling deal with the quality of an OO design. Generally, good OO design should be loosely coupled and highly cohesive. Lot of the design principles, design patterns which have been created are based on the idea of “Loose coupling and high cohesion”.
The aim of the design should be to make the application:
- easier to develop
- easier to maintain
- easier to add new features
- less Fragile.
Coupling is the degree to which one class knows about another class. Let us consider two classes class A and class B. If class A knows class B through its interface only i.e it interacts with class B through its API then class A and class B are said to be loosely coupled.