Using new PHP7 operator "..." to provide variable number of arguments into constructor we can easier manage child classes constructor interfaces.

constructor-arguments.php

<?php

class ParentClass
{
    public $a;
    public $b;

    public function __construct($a, $b)
    {
        $this->a = $a;
        $this->b = $b;
    }
}

class ChildClass extends ParentClass
{
    public $c;

    /**
     * Using ... we can add any amount of arguments in ParentClass constructor
     * w/o breaking ChildClass constructor interface.
     */
    public function __construct($c, ...$parentArgs)
    {
        parent::__construct(...$parentArgs);
        $this->c = $c;
    }
}

list($a, $b, $c) = ['a', 'b', 'c'];
$obj = new ChildClass($a, $b, $c);

var_dump($obj);