In PHP, can you instantiate an object and call a method on the same line?

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没有蜡笔的小新
没有蜡笔的小新 2020-11-27 14:01

What I would like to do is something like this:

$method_result = new Obj()->method();

Instead of having to do:

$obj = ne         


        
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  •  时光取名叫无心
    2020-11-27 14:15

    You cannot do what you are asking ; but you can "cheat", using the fact that, in PHP, you can have a function that has the same name as a class ; those names won't conflict.

    So, if you declared a class like this :

    class Test {
        public function __construct($param) {
            $this->_var = $param;
        }
        public function myMethod() {
            return $this->_var * 2;
        }
        protected $_var;
    }
    

    You can then declare a function that returns an instance of that class -- and has exactly the same name as the class :

    function Test($param) {
        return new Test($param);
    }
    

    And now, it becomes possible to use a one-liner, like you asked -- only thing is you are calling the function, thus not using new :

    $a = Test(10)->myMethod();
    var_dump($a);
    

    And it works : here, I'm getting :

    int 20
    

    as output.


    And, better, you can put some phpdoc on your function :

    /**
     * @return Test
     */
    function Test($param) {
        return new Test($param);
    }
    

    This way, you'll even have hints in your IDE -- at least, with Eclipse PDT 2.x ; see the screeshot :



    Edit 2010-11-30 : Just for information, a new RFC has been submitted, a few days ago, that proposes to add this feature to one of the future versions of PHP.

    See : Request for Comments: Instance and method call/property access

    So, maybe doing things like these will be possible in PHP 5.4 or another future version :

    (new foo())->bar()
    (new $foo())->bar
    (new $bar->y)->x
    (new foo)[0]
    

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