php中Closure::bind用法(手册记录)

　　手册中　Closure::bind — 复制一个闭包，绑定指定的$this对象和类作用域。

　　具体参数可以看手册，这里记录下这个方法的实际用处．

<?php

trait MetaTrait
{
    private $methods = [];

    public function addMethod($methodName,$methodCallable)
    {
        if (!is_callable($methodCallable))
            throw new InvalidArgumentException('Second param must be callable');

        //改变作用域到 get_called_class 的对象
        $this->methods[$methodName] = Closure::bind($methodCallable, $this, get_called_class());

    }

    public function __call($methodName, array $args)
    {
        if (isset($this->methods[$methodName])){
            return call_user_func_array($this->methods[$methodName],$args);
        }

        throw new RuntimeException('There is no method with the given name to call');

    }

}

class HackThursday
{
    use MetaTrait;

    private $dayOfWeek = 'Thursday';
}


$test = new HackThursday();
$test->addMethod('when',function(){
    return $this->dayOfWeek;
});

echo $test->when(); //Thursday

　　其实这个方法就是以前说过的 Closure::bindTo() 的静态版本, 和PHP 使用reflection时的问题,以及解决方案这篇一起看加深理解．