Dependency Injection for Mere Humans
summary
Distinguishes service locator from dependency injection, proves DI by refactoring an order processor: extracts four concrete dependencies (repository, logger, time, mailer), converts static mailer to an injected instance, moves current time from constructor to method parameter and uses a null logger pattern; demonstrates Constructor injection, parameter injection and lazy wiring with a PSR-11 container (Pimple and a 140/280-character toy container), warns against using the container as a service locator.
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chapters (16)
- 0:00Dependency Injection intro
- 1:08Why DI matters
- 4:46Class-level dependencies
- 10:24Obscure dependencies
- 13:55Refactoring to dependency injection
- 15:21Constructor injection
- 18:57Setter injection options
- 25:24Optional dependencies
- 27:11Parameter injection
- 31:01Dependency inversion
- 38:06Refactoring step-by-step
- 42:47How DI containers work
- 49:29PSR-11 container
- 51:14FizzBuzz container example
- 53:45Pimple in Slim
- 56:18Summary
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