Solid PHP - solid principles in PHP

PHP code examples for the SOLID rules, referring to the blog post: Solid PHP - SOLID principles in PHP

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Single responsibility principle (SRP)

There should never be more than one reason for a class to change.

SRP - explanation

Examples:

• single-responsibility-principle BAD
• single-responsibility-principle GOOD

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Open/closed principle (OCP)

Software entities ... should be open for extension, but closed for modification.

OCP - explanation

Examples:

• open-closed-principle BAD
• open-closed-principle GOOD

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Liskov substitution principle (LSP)

Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it.

LSP - explanation

Examples:

• liskov-substitution-principle BAD
• liskov-substitution-principle GOOD

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Interface segregation principle (ISP)

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

ISP - explanation

Examples:

• interface-segregation-principle BAD
• interface-segregation-principle GOOD

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Dependency inversion principle (DIP)

Depend upon abstractions, NOT concretions.

DIP - explanation

Examples:

• dependency-inversion-principle BAD
• dependency-inversion-principle GOOD