SOLID

Question 1

What are the solid principles

Answer 1

Single responsibility 
Open/closed principle 
Liskov substitution 
Interface segregation 
Dependency inversion

Question 2

What is liskov substitution

Answer 2

If class A is a subtype of Class B then we should be able to replace Class B with A without disrupting the behavior of the program

Question 3

Interface segregation

Answer 3

Larger interfaces must be split into smaller ones , by this we can ensure that implementing classes are only concerned about methods that are of interest to them

Question 4

Dependency inversion

Answer 4

Refers to decoupling of software modules
High level modules must not depend on low level modules. they must be dependent only on abstractions

The idea is to compose a class with its dependent classes and inject the dependencies through a constructor instead of doing new