yii2框架随笔18

<?php

        /**
     * Sets value of an object property.
     * 设置对象的属性值。
     * Do not call this method directly as it is a PHP magic method that
     * will be implicitly called when executing `$object->property = $value;`.
     *
     * 魔术方法，实现 setter
     *
     * @param string $name the property name or the event name
     * @param mixed $value the property value
     * @throws UnknownPropertyException if the property is not defined
     * @throws InvalidCallException if the property is read-only
     * @see __get()
     */
    public function __set($name, $value)
    {
        $setter = ‘set‘ . $name;
        if (method_exists($this, $setter)) {
            // 对象存在 $setter 方法，就直接调用
            $this->$setter($value);
        } elseif (method_exists($this, ‘get‘ . $name)) {
            // 如果存在 ‘get‘ . $name 方法，就认为该属性是只读的
            throw new InvalidCallException(‘Setting read-only property: ‘ . get_class($this) . ‘::‘ . $name);
        } else {
            // 否则认为该属性不存在
            throw new UnknownPropertyException(‘Setting unknown property: ‘ . get_class($this) . ‘::‘ . $name);
        }
    }

     /**
     * Checks if the named property is set (not null).
     * 检查属性是否被设置
     *
     * Do not call this method directly as it is a PHP magic method that
     * will be implicitly called when executing `isset($object->property)`.
     * 不要直接调用这个方法,因为它是一个PHP魔术方法呢，调用执行`isset($object->property)`。
     * Note that if the property is not defined, false will be returned.
     *
     * 魔术方法，实现 isset，基于 getter 实现，有 getter 方法的属性才算存在
     *
     * @param string $name the property name or the event name
     * @return boolean whether the named property is set (not null).
     */
    public function __isset($name)
        {
        $getter = ‘get‘ . $name;
        if (method_exists($this, $getter)) {
            // 有 $getter 方法且获取的值不为 null，才认为该属性存在
            return $this->$getter() !== null;
        } else {
            return false;
        }
    }
    /**
     * Sets an object property to null.
     *
     * Do not call this method directly as it is a PHP magic method that
     * will be implicitly called when executing `unset($object->property)`.
     * 不要直接调用这个方法,因为它是一个PHP魔术方法呢，调用执行`isset($object->property)`。
     * Note that if the property is not defined, this method will do nothing.
     * If the property is read-only, it will throw an exception.
     *
     * 魔术方法，实现 unset，基于 setter 实现，有 setter 方法的属性才能 unset 掉
     *
     * @param string $name the property name
     * @throws InvalidCallException if the property is read only.
     */
    public function __unset($name)
    {
        $setter = ‘set‘ . $name;
        if (method_exists($this, $setter)) {
            // 通过 $setter 方法，将它设置为 null
            $this->$setter(null);
        } elseif (method_exists($this, ‘get‘ . $name)) {
            // 如果存在 ‘get‘ . $name 方法，就认为该属性是只读的
            throw new InvalidCallException(‘Unsetting read-only property: ‘ . get_class($this) . ‘::‘ . $name);
        }
    }
    /**
     * Calls the named method which is not a class method.
     *
     * Do not call this method directly as it is a PHP magic method that
     * will be implicitly called when an unknown method is being invoked.
     * 重写了__call（）方法，在调用不存在的方法时会调用此方法，抛出异常
     * @param string $name the method name
     * @param array $params method parameters
     * @throws UnknownMethodException when calling unknown method
     * @return mixed the method return value
     */
    public function __call($name, $params)
    {
        throw new UnknownMethodException(‘Calling unknown method: ‘ . get_class($this) . 
    "::$name()");
    }
    /**
     * Returns a value indicating whether a property is defined.
     * 返回一个值指示是否定义属性。
     * A property is defined if:
     *
     * - the class has a getter or setter method associated with the specified name
     *   (in this case, property name is case-insensitive);
     * - the class has a member variable with the specified name (when `$checkVars` is true);
     *
     * 检查对象或类是否具有 $name 属性，如果 $checkVars 为 true，则不局限于是否有 getter/setter
     *
     * @param string $name the property name
     * @param boolean $checkVars whether to treat member variables as properties
     * @return boolean whether the property is defined
     * @see canGetProperty()
     * @see canSetProperty()
     */
    public function hasProperty($name, $checkVars = true)
    {
        return $this->canGetProperty($name, $checkVars) || $this->canSetProperty($name, false);
    }
    /**
     * Returns a value indicating whether a property can be read.
     * A property is readable if:
     *
     * - the class has a getter method associated with the specified name
     *   (in this case, property name is case-insensitive);
     * - the class has a member variable with the specified name (when `$checkVars` is true);
     *
     * 检查对象或类是否能够获取 $name 属性，如果 $checkVars 为 true，则不局限于是否有 getter
     *
     * @param string $name the property name
     * @param boolean $checkVars whether to treat member variables as properties
     * @return boolean whether the property can be read
     * @see canSetProperty()