Slide of talk in [PHP 也有 Day]

1. Dependency Inversion
Dependency Injection
Contract
SOLID
Service Provider
Service Container
IoC
DI

2. Dependency Inversion
SOLID
High-level modules should not depend on
low-level modules. Both should depend
on abstractions.
http://en.wikipedia.org/wiki/Dependency_inversion_principle

3. ⾼高階模組不應該依賴低階模組。
兩者都應該要依賴於抽象
What the …

4. class UserModify {
public function __constructor() {
$this->storage = new MysqlStorage();
}
public function modify($data) {
$result = $this->storage->save($data);
return $result;
}
}
⾼高階直接依賴低階

6. class UserModify {
public function __constructor(DataStorageInterface $storage) {
$this->storage = $storage;
}
public function modify($data) {
$result = $this->storage->save($data);
return $result;
}
}
class MysqlStorage implements DataStorageInterface {
public function save($data){ // …. }
}
interface DataStorageInterface {
public function save(array $data);
}
Abstraction
Low Level Module
Hight Level Module

7. Why

8. #隱藏低階模組的細節
#容易抽換實作
#程式碼變多
#追蹤⽐比較困難
#讓測試變容易 #⽐比較不直覺

9. 隱藏低階模組的細節
class UserModify {
public function __constructor() {
$dbConfig = [….];
$this->storage = new MysqlStorage($dbConfig);
}
}

10. 容易抽換實作
class UserModify {
public function __constructor(DataStorageInterface $storage) {
$this->storage = $storage;
}
}
class SqliteStorage implements DataStorageInterface {
public function save($data){ // …. }
}
SqliteStorage Instance

11. 讓測試變容易
class DummyStorage implements DataStorageInterface {
public function save() { return ‘Success’; }
}
class UserModify {
public function modify($data) {
return $this->storage->save($data);
}
}
class UserModifyTest {
public function it_return_new_instance_after_modify($data) {
$instance = new UserModify(new DummyStorage);
$result = $instance->modify();
assert($result, ‘Success’);
}
}

12. How

13. Inverse of Control
http://zh.wikipedia.org/wiki/%E6%8E%A7%E5%88%B6%E5%8F%8D%E8%BD%AC

14. Dependency Injection
http://en.wikipedia.org/wiki/Dependency_injection
Dependency injection is a software design
pattern that implements inversion of control for
software libraries, where the caller delegates to
an external framework the control flow of
discovering and importing a service or software
module.

15. Service
Provider
Container

17. http://laravel.tw/docs/5.0/providers
Service Provider

18. .
├── AppServiceProvider.php
├── BusServiceProvider.php
├── ConfigServiceProvider.php
├── EventServiceProvider.php
├── FilterServiceProvider.php
├── RepoServiceProvider.php
└── RouteServiceProvider.php
app/Providers

19. <?php namespace BackendProviders;
use IlluminateSupportServiceProvider;
class AppServiceProvider extends ServiceProvider {
public function register() {
$this->app->bind(
‘Jaster/Interfaces/FooInterface’,
‘Jaster/Implements/FooImplementClass’
);
}
}
app/Providers/AppServiceProvider.php

20. 'providers' => [
/*
* Laravel Framework Service Providers...
*/
'IlluminateFoundationProvidersArtisanServiceProvider',
'IlluminateAuthAuthServiceProvider',
'IlluminateBusBusServiceProvider',
'IlluminateCacheCacheServiceProvider',
'IlluminateFoundationProvidersConsoleSupportServiceProvider',
'IlluminateRoutingControllerServiceProvider',
// ….
],
config/app.php

21. Service Container
The Laravel service container is a powerful tool
for managing class dependencies. Dependency
injection is a fancy word that essentially means
this: class dependencies are "injected" into the
class via the constructor or, in some cases,
"setter" methods.
http://laravel.com/docs/5.0/container

22. Trace initialize of service container ( IlluminateFoundationApplication )
IlluminateFoundationApplication::__construct
IlluminateFoundationApplication::registerBaseBindings
IlluminateFoundationApplication::registerBaseServiceProviders
IlluminateFoundationApplication::registerCoreContainerAliases

23. Trace register of IlluminateContractsHttpKernel
bootstrap/app.php
$app->singleton(‘IlluminateContractsHttpKernel', 'AppHttpKernel');
IlluminateFoundationApplication::singleton
IlluminateFoundationApplication::bind

24. Trace how to use IlluminateContractsHttpKernel
$kernel = $app->make('IlluminateContractsHttpKernel');
public/index.php
IlluminateFoundationApplication::make
IlluminateContainerContainer::make
IlluminateContainerContainer::build

25. Trace Facade autoloader
IlluminateFoundationHttpKernel::bootstrap
IlluminateFoundationApplication::bootstrapWith
IlluminateFoundationBootstrapRegisterFacades
IlluminateFoundationAliasLoader::register
IlluminateFoundationAliasLoader::prependToLoaderStack

26. PHP UK Conference 2014 - Stephan Hochdorfer -
The 7 Deadly Sins of Dependency Injection
https://www.youtube.com/watch?v=hMix8gfDy54

27. Thank you