D
SOLID Principles for WordPress Development
Dependency Inversion Principle in WordPress
Depend on abstractions, not on concrete implementations
The Dependency Inversion Principle (DIP) states that high-level modules should not depend on low-level modules — both should depend on abstractions. This makes your code flexible, testable, and easy to swap out implementations.
Depend on Abstractions
Swappable Implementations
Easy to Test
Why DIP Matters for WordPress Developers
Depend on interfaces, inject implementations. Your business logic stays clean, tests become trivial, and swapping vendors never requires rewriting your core plugin.
Testability
Inject mocks in unit tests — no WordPress environment, no DB, no mail server needed
Flexibility
Swap Mailchimp for SendGrid, MySQL for Redis — without touching a single line of business logic
Clean Architecture
High-level domain logic stays pure — no infrastructure leaking into your business rules