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42. Design Patterns in PHP

Structuring larger applications.

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Common object-oriented patterns translate naturally to PHP: Singleton (a private constructor plus a static getInstance()), Factory (a method that returns different concrete implementations behind a shared interface), and Dependency Injection (passing collaborators into a constructor rather than hardcoding them). These patterns improve testability and decoupling.

Modern PHP frameworks like Laravel and Symfony rely heavily on DI containers to automatically resolve and inject class dependencies based on type hints, reducing manual wiring.

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Check your understanding

1. What is the core idea of Dependency Injection?
Classes create their own dependencies internallyDependencies are passed in from outside, e.g. via constructorAll classes must be staticDependencies are global variables
2. What does the Factory pattern typically provide?
A single global instanceA method that creates and returns objects behind a common interfaceA way to serialize objectsA caching layer

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