SOLID Principles Examples in PHP

Single Responsibility Principle

A class should have one, and only one, reason to change. Example

Open Closed Principle

A class should be open for extension, but closed for modification. Example

Liskov Substitution Principle

Derived classes must be substitutable for their base classes. Example

Interface Segregation Principle

Many client-specific interfaces are better than one general-purpose interface. Example

Dependency Inversion Principle

Depend upon abstractions. Do not depend upon concretions. Example

For more information about Object Oriented Design Principles, you can refer this slide