The ReflectionMethod class

Note that the public member $class contains the name of the class in which the method has been defined:

<?php
class A {public function __construct() {}}
class B extends A {}

$method = new ReflectionMethod('B', '__construct');
echo $method->class; // prints 'A'
?>

We can make a "Automatic dependenci injector" in classes when her constructors depends other classes (with type hint).

<?php

class Dependence1 {
    function foo() {
        echo "foo";
    }
}

class Dependence2 {
    function foo2() {
        echo "foo2";
    }
}

final class myClass
{
    private $dep1;
    private $dep2;

    public function __construct(
        Dependence1 $dependence1, 
        Dependence2 $dependence2
    )
    {
        $this->dep1 = $dependence1;
        $this->dep2 = $dependence2;        
    }
    
}

// Automatic dependence injection (CLASSES)

$constructor = new ReflectionMethod(myClass::class, '__construct');
$parameters = $constructor->getParameters();

$dependences = [];
foreach ($parameters as $parameter) {
    $dependenceClass = (string) $parameter->getType();
    $dependences[] = new $dependenceClass();
}

$instance = new myClass(...$dependences);
var_dump($instance);

?>

Results in: 

object(myClass)#6 (2) {
  ["dep1":"myClass":private]=>
  object(Dependence1)#4 (0) {
  }
  ["dep2":"myClass":private]=>
  object(Dependence2)#5 (0) {
  }
}