When including an initialization function within both A and B classes, creating an instance of he extending B class resets the variable
value created by initialization function withing the A class

class A {
	var $var_a;
	function A() {
		$this->var_a = "a";
	}
}

class B extends A {
	var $var_b;
	function B() {
		$this->var_b = "b";
	}
}

$test = new B;
echo $test->var_a; //no output unless I comment out function B() in class B
echo $test->var_b;