yii2框架随笔26

继续来看Container.php

<?php
    /**
     * Registers a class definition with this container.
     * 用这个容器注册一个类定义。
     * If a class definition with the same name already exists, it will be overwritten with the new one.
     * 如果已存在具有相同名称的类的定义，它将被新的覆盖。
     * You may use [[has()]] to check if a class definition already exists.
     * 您可以使用[[has()]]检查一个类定义是否已经存在.
     * @param string $class class name, interface name or alias name
     * @param mixed $definition the definition associated with `$class`. It can be one of the followings:
     * @param array $params the list of constructor parameters. The parameters will be passed to the class
     * constructor when [[get()]] is called.
     * @return static the container itself
     */
    public function set($class, $definition = [], array $params = [])
    {
        // 处理definition，并存入到_definitions中
        $this->_definitions[$class] = $this->normalizeDefinition($class, $definition);
        // 将$params存入_params中
        $this->_params[$class] = $params;
        unset($this->_singletons[$class]);
        return $this;
    }

     /**
     * Registers a class definition with this container and marks the class as a singleton class.
     * 用这个容器注册一个类定义，并将该类定义为一个单独的类。
     * This method is similar to [[set()]] except that classes registered via this method will only have one
     * instance. Each time [[get()]] is called, the same instance of the specified class will be returned.
     * 这种方法类似于 [[set()]]除了类注册通过这种方法只有一个实例。每一次[[get()]]之称，指定类的同一实例将返回
     * @param string $class class name, interface name or alias name
     * @param mixed $definition the definition associated with `$class`. See [[set()]] for more details.
     * @param array $params the list of constructor parameters. The parameters will be passed to the class
     * constructor when [[get()]] is called.
     * @return static the container itself
     * @see set()
     */
    public function setSingleton($class, $definition = [], array $params = [])
    {
        // 同上
        $this->_definitions[$class] = $this->normalizeDefinition($class, $definition);
        $this->_params[$class] = $params;
        // 这里是单例，表示这个还会继续用到，所以不用unset，只需赋为空即可
        $this->_singletons[$class] = null;
        return $this;
    }
    /**
     * Returns a value indicating whether the container has the definition of the specified name.
     * 返回一个值，该值指示容器是否具有指定名称的定义。
     * @param string $class class name, interface name or alias name
     * @return boolean whether the container has the definition of the specified name..
     * @see set()
     */
    public function has($class)
    {
        // 判断是否已经定义了某个服务或组件
        return isset($this->_definitions[$class]);
    }
    /**
     * Returns a value indicating whether the given name corresponds to a registered singleton.
     * 返回一个值，该值指示给定的名称是否对应于已注册的单体.
     * @param string $class class name, interface name or alias name
     * @param boolean $checkInstance whether to check if the singleton has been instantiated.
     * @return boolean whether the given name corresponds to a registered singleton. If `$checkInstance` is true,
     * the method should return a value indicating whether the singleton has been instantiated.
     */
    public function hasSingleton($class, $checkInstance = false)
    {
        // 当 $checkInstance === false 时，用于判断是否已经定义了某个服务或组件
        // 当 $checkInstance === true 时，用于判断是否已经有了某人服务或组件的实例
        return $checkInstance ? isset($this->_singletons[$class]) : array_key_exists($class, $this->_singletons);
    }
    /**
     * Removes the definition for the specified name.
     * @param string $class class name, interface name or alias name
     */
    public function clear($class)
    {
        // 清空相应类的definition和singleton
        unset($this->_definitions[$class], $this->_singletons[$class]);
    }
    /**
     * Normalizes the class definition.
     * 将类定义.
     * @param string $class class name
     * @param string|array|callable $definition the class definition
     * @return array the normalized class definition
     * @throws InvalidConfigException if the definition is invalid.
     */
    protected function normalizeDefinition($class, $definition)
    {
        if (empty($definition)) {
            // 定义为空
            return ['class' => $class];
        } elseif (is_string($definition)) {
            // $definition是字符串，就表明它是类名，$class是简称
            return ['class' => $definition];
        } elseif (is_callable($definition, true) || is_object($definition)) {
            // 是个PHP callable或者是个对象，就直接返回
            return $definition;
        } elseif (is_array($definition)) {
            // 是个数组
            if (!isset($definition['class'])) {
                // 定义中不存在class键，$class必须是带namespace的类名
                if (strpos($class, '\\') !== false) {
                    $definition['class'] = $class;
                } else {
                    throw new InvalidConfigException("A class definition requires a \"class\" member.");
                }
            }
            return $definition;
        } else {
            throw new InvalidConfigException("Unsupported definition type for \"$class\": " . gettype($definition));
        }
    }
    /**
     * Returns the list of the object definitions or the loaded shared objects.
     * 返回对象定义或加载的共享对象的列表。
     * @return array the list of the object definitions or the loaded shared objects (type or ID => definition or instance).
     */
    public function getDefinitions()
    {
        return $this->_definitions;
    }