空对象模式

<?php

abstract class Person
{
    protected $_name;

    abstract public function getName();
}

class RealPerson extends Person
{
    function __construct($name)
    {
        $this->_name = $name;
    }

    public function getName()
    {
        echo "我的名字是：{$this->_name}";
    }
}

class NullPerson extends Person
{
    public function getName()
    {
        echo "<br/>我不是人类哦";
    }
}




class Factory
{
    private $_names = ['A', 'B', 'C'];

    public function produce($personName)
    {
        if (array_search($personName, $this->_names) !== false) {
            return new RealPerson($personName);
        }

        return new NullPerson();
    }
}



$f = new Factory();
$p1 = $f->produce('A');
$p1->getName();

$p2 = $f->produce('G');
$p2->getName();