e-strict.php

<?php

class A
{
    public function hello(B $b)
    {
        echo "Hello {$b->person}" . PHP_EOL;
    }
}

class B
{
    public $person = 'Till';
}

class C extends A
{
    public function hello($name)
    {
        echo "Hello {$name}" . PHP_EOL;
    }
}

$a = new A;
$b = new B;

$a->hello($b);

$c = new A;
$c->hello('Nils');

scalar-madness.php

<?php

class A
{
 public function sum(int $number, int $anotherNumber)
 {
  //
 }
}

class B extends A
{
 public function sum($number, int $anotherNumber)
 {
  //
 }
}