PHP之依赖注入容器pimple

原文地址：http://blog.csdn.net/wzllai/article/details/24485245

依赖注入（Dependency Injection）又叫控制反转（Inversion of Control）是一个重要的面向对象编程的法则来削减计算机程序的耦合问题，它能消除组件间的直接依赖关系，让组件的开发更独立，使用更灵活，在java框架中应用非常广泛。在php中由于语言特性不能完全照搬java的那一套，但简单的功能还是可以实现的。pimple就是php社区中比较流行的一种ioc容器。

可以用composer添加 require  "pimple/pimple": "1.*"

pimple的优势是简单，就一个文件

/*  * This file is part of Pimple.  *  * Copyright (c) 2009 Fabien Potencier  *  * Permission is hereby granted, free of charge, to any person obtaining a copy  * of this software and associated documentation files (the "Software"), to deal  * in the Software without restriction, including without limitation the rights  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell  * copies of the Software, and to permit persons to whom the Software is furnished  * to do so, subject to the following conditions:  *  * The above copyright notice and this permission notice shall be included in all  * copies or substantial portions of the Software.  *  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN  * THE SOFTWARE.  */    /**  * Pimple main class.  *  * @package pimple  * @author  Fabien Potencier  */  class Pimple implements \ArrayAccess  {      private $values = array();      private $factories;      private $protected;      private $frozen = array();      private $raw = array();      private $keys = array();        /**      * Instantiate the container.      *      * Objects and parameters can be passed as argument to the constructor.      *      * @param array $values The parameters or objects.      */      public function __construct(array $values = array())      {          $this->factories = new \SplObjectStorage();          $this->protected = new \SplObjectStorage();            foreach ($values as $key => $value) {              $this->offsetSet($key, $value);          }      }        /**      * Sets a parameter or an object.      *      * Objects must be defined as Closures.      *      * Allowing any PHP callable leads to difficult to debug problems      * as function names (strings) are callable (creating a function with      * the same name as an existing parameter would break your container).      *      * @param  string           $id    The unique identifier for the parameter or object      * @param  mixed            $value The value of the parameter or a closure to define an object      * @throws RuntimeException Prevent override of a frozen service      */      public function offsetSet($id, $value)      {          if (isset($this->frozen[$id])) {              throw new \RuntimeException(sprintf('Cannot override frozen service "%s".', $id));          }            $this->values[$id] = $value;          $this->keys[$id] = true;      }        /**      * Gets a parameter or an object.      *      * @param string $id The unique identifier for the parameter or object      *      * @return mixed The value of the parameter or an object      *      * @throws InvalidArgumentException if the identifier is not defined      */      public function offsetGet($id)      {          if (!isset($this->keys[$id])) {              throw new \InvalidArgumentException(sprintf('Identifier "%s" is not defined.', $id));          }            if (              isset($this->raw[$id])              || !is_object($this->values[$id])              || isset($this->protected[$this->values[$id]])              || !method_exists($this->values[$id], '__invoke')          ) {              return $this->values[$id];          }            if (isset($this->factories[$this->values[$id]])) {              return $this->values[$id]($this);          }            $this->frozen[$id] = true;          $this->raw[$id] = $this->values[$id];            return $this->values[$id] = $this->values[$id]($this);      }        /**      * Checks if a parameter or an object is set.      *      * @param string $id The unique identifier for the parameter or object      *      * @return Boolean      */      public function offsetExists($id)      {          return isset($this->keys[$id]);      }        /**      * Unsets a parameter or an object.      *      * @param string $id The unique identifier for the parameter or object      */      public function offsetUnset($id)      {          if (isset($this->keys[$id])) {              if (is_object($this->values[$id])) {                  unset($this->factories[$this->values[$id]], $this->protected[$this->values[$id]]);              }                unset($this->values[$id], $this->frozen[$id], $this->raw[$id], $this->keys[$id]);          }      }        /**      * Marks a callable as being a factory service.      *      * @param callable $callable A service definition to be used as a factory      *      * @return callable The passed callable      *      * @throws InvalidArgumentException Service definition has to be a closure of an invokable object      */      public function factory($callable)      {          if (!is_object($callable) || !method_exists($callable, '__invoke')) {              throw new \InvalidArgumentException('Service definition is not a Closure or invokable object.');          }            $this->factories->attach($callable);            return $callable;      }        /**      * Protects a callable from being interpreted as a service.      *      * This is useful when you want to store a callable as a parameter.      *      * @param callable $callable A callable to protect from being evaluated      *      * @return callable The passed callable      *      * @throws InvalidArgumentException Service definition has to be a closure of an invokable object      */      public function protect($callable)      {          if (!is_object($callable) || !method_exists($callable, '__invoke')) {              throw new \InvalidArgumentException('Callable is not a Closure or invokable object.');          }            $this->protected->attach($callable);            return $callable;      }        /**      * Gets a parameter or the closure defining an object.      *      * @param string $id The unique identifier for the parameter or object      *      * @return mixed The value of the parameter or the closure defining an object      *      * @throws InvalidArgumentException if the identifier is not defined      */      public function raw($id)      {          if (!isset($this->keys[$id])) {              throw new \InvalidArgumentException(sprintf('Identifier "%s" is not defined.', $id));          }            if (isset($this->raw[$id])) {              return $this->raw[$id];          }            return $this->values[$id];      }        /**      * Extends an object definition.      *      * Useful when you want to extend an existing object definition,      * without necessarily loading that object.      *      * @param string   $id       The unique identifier for the object      * @param callable $callable A service definition to extend the original      *      * @return callable The wrapped callable      *      * @throws InvalidArgumentException if the identifier is not defined or not a service definition      */      public function extend($id, $callable)      {          if (!isset($this->keys[$id])) {              throw new \InvalidArgumentException(sprintf('Identifier "%s" is not defined.', $id));          }            if (!is_object($this->values[$id]) || !method_exists($this->values[$id], '__invoke')) {              throw new \InvalidArgumentException(sprintf('Identifier "%s" does not contain an object definition.', $id));          }            if (!is_object($callable) || !method_exists($callable, '__invoke')) {              throw new \InvalidArgumentException('Extension service definition is not a Closure or invokable object.');          }            $factory = $this->values[$id];            $extended = function ($c) use ($callable, $factory) {              return $callable($factory($c), $c);          };            if (isset($this->factories[$factory])) {              $this->factories->detach($factory);              $this->factories->attach($extended);          }            return $this[$id] = $extended;      }        /**      * Returns all defined value names.      *      * @return array An array of value names      */      public function keys()      {          return array_keys($this->values);      }  }  

pimple类就继承一个php数组对象接口，在程序整个生命周期中，各种属性、方法、对象、闭包都可以注册其中，得易于php的数组的hashtable实现，容器本身的查询效率不算是太低。类似zf1中的Zend_Register或者Yii的委托代理形式，总体来说还是pimple直观些。

pimple只是实现了一个容器的概念，关于依赖注入自动创建关联对象的功能可以参照Laravel4和z2中的实现。一个例子代码:

class A{}class B{public function __construct(A a){}}class C{public function __construct(B b){}public function dosomething(){}}$container = new pimple;$container->a = function () {return new A();};$c->b = function ($c) {return new B($c->a);};$c->c = function ($c) {return new C($c->b);};// 从容器中取得Foo$foo = $c->foo;$foo->doSomething();// Bim::doSomething|Bar::doSomething|Foo::doSomething// 依赖注入的核心就是将对象和类的依赖关系注册到容器中。