Question

1. What are the five SOLID principles of class design? Explain with examples how they inform our design choices. Are these related to each other in any way?

Answer 1

The five SOLID class design principle are as follows

1. Single responsibility: The class should be responsible for a single functionality. For eg. let us have a simulation class that should load the simulation data but should not perform any simulation calculation.

2. Open Closed principle: The class should allow extension but disallow modification. For eg. let us have a employee class which can be extended to create another class regular employee. But we should not change the employee class otherwise the regular employee class would also change

3. Liskov substitution principle: According to this principle, the class object should be replaceable with its subtype. For eg. let us have a class abc as parent and pqr as child class. we should be able to use the child class pqr object to reference abc class

4. Interface segregation: The classes should have general interface which can be easily used instead of specific interface. For eg. An interface should be designed in such a way that it can be used by classes without need to declare specific interfaces

5. Dependency inversion: The class should use abstraction instead of depending on concreate class. For eg. there are two classes A and B. A uses the high level module that directly uses the lower level module from B, SO if we change anything in class A, it would be necessary to make the corresponding changes in class B too.

Yes, these principles are closely related with each other and plays very important role in software development.