PHP[OOP] - How to call class constructor manually?

Question

Please see the code bellow:

01. class Test {
02.     public function __construct($param1, $param2, $param3) {
03.         echo $param1.$para         


        

Answer 1

If separating instantiation from initialization isn't strictly a requirement, there are two other possibilities: first, a static factory method.

class Test {
    public function __construct($param1, $param2, $param3) {
        echo $param1.$param2.$param3;
    }

    public static function CreateTest($param1, $param2, $param3) {
        return new Test($param1, $param2, $param3);
    }
}

$params = array('p1','p2','p3');

if(method_exists($ob,'__construct')) {
    call_user_func_array(array($ob,'CreateTest'),$params);
}

Or, if you're using php 5.3.0 or higher, you can use a lambda:

class Test {
    public function __construct($param1, $param2, $param3) {
        echo $param1.$param2.$param3;
    }
}

$params = array('p1','p2','p3');

$func = function ($arg1, $arg2, $arg3) {
    return new Test($arg1, $arg2, $arg3);
}

if(method_exists($ob,'__construct')) {
    call_user_func_array($func, $params);
}

The initialization method described by Asaph is great if for some reason you have a need to logically separate initialization from instantiation, but if supporting your use case above is a special case, not a regular requirement, it can be inconvenient to require users to instantiate and initialize your object in two separate steps.

The factory method is nice because it gives you a method to call to get an initialized instance. The object is initialized and instantiated in the same operation, though, so if you have a need to separate the two it won't work.

And lastly, I recommend the lambda if this initialization mechanism is uncommonly used, and you don't want to clutter your class definition with initialization or factory methods that will hardly ever be used.