gistfile1.php

<?php

class Foo1 {

    private $bar;

    public function getBar() {
        if(!$this->bar) {
            $this->bar = new Bar();
        }
        return $this->bar;
    }

}


class Foo2 {

    private $bar;

    public function __construct() {
        $this->setBar(new Bar());
    }

    public function setBar(Bar $bar) {
        $this->bar = $bar;
        return $this;
    }

    public function getBar() {
        return $this->bar;
    }

}


class Foo3 {

    private $bar;

    public function setBar(Bar $bar) {
        $this->bar = $bar;
        return $this;
    }

    public function getBar() {
        if(!$this->bar) {
            $this->setBar(new Bar());
        }
        return $this->bar;
    }

}