动态实例化包含在数组中的PHP类

Question

I'm trying to instantiate some classes in an array. This is the scenario: I have many classes, e.g.:

class Class0 extends NumberedClasses{...}
class Class1 extends NumberedClasses{...}
class Class2 extends NumberedClasses{...}

They will increase over the time, so instead of instantiating them this way:

$instances0 = new Class0();
$instances1 = new Class1();
$instances2 = new Class2();

I want to have a getter method, like this one:

function getStrategies(){
   return array(Class0, Class1, Class2);
}

So I can just add classses in that array in the future, and call it this way:

$strategies = $this->getStrategies();
for ($strategies as $strategy) { 
    $instance = new $strategy();
}

I'm used to do something similar with js, where I have the window object, so I can instantiate classes even just with a string (new window["Class1"]). But I'm new with PHP and can't find the way to do that.

Thanks in advance,

Answer 1

It may be suggested that using an Intermediary Class to manage these instances will be much ideal. Consider this:

    <?php

        class NumberedClasses{}
        class Class0 extends NumberedClasses{}
        class Class1 extends NumberedClasses{}
        class Class2 extends NumberedClasses{}


        class InstanceHelper {

            /**
             * @var array
             */
            protected $instances = array();

            public function addInstance($instanceKey, $instance) {
                if(!array_key_exists($instanceKey, $this->instances)){
                    $this->instances[$instanceKey] = $instance ;
                }
            }

            public function addInstances(array $arrayOfInstances) {
                foreach($arrayOfInstances as $instanceKey=>$instance){
                    if(!array_key_exists($instanceKey, $this->instances)){
                        $this->instances[$instanceKey] = $instance ;
                    }
                }
            }

            public function removeInstance($instanceKey) {
                if(array_key_exists($instanceKey, $this->instances)){
                    unset($this->instances[$instanceKey]);
                }
                return $this->instances;
            }

            public function getAllInstances() {
                return $this->instances;
            }
        }

Now; with the Class InstanceHelper, You can easily manage your instances... even add Instances, remove Instance and so on.... Again consider this tests:

    <?php

        $insHelper          = new InstanceHelper();
        $instances          = array(
            'c0'    =>  new Class0(),
            'c1'    =>  new Class1(),
            'c2'    =>  new Class2(),
        );

        $insHelper->addInstances($instances);

        var_dump($insHelper->getAllInstances());
        var_dump($insHelper->removeInstance('c1'));

Here are the results of both var_dumps:

        ::VAR_DUMP 1::
        array (size=3)
          'c0' => 
            object(Class0)[2]
          'c1' => 
            object(Class1)[3]
          'c2' => 
            object(Class2)[4]



        ::VAR_DUMP 2::
        array (size=2)
          'c0' => 
            object(Class0)[2]
          'c2' => 
            object(Class2)[4]