策略模式-在php上返回一个未定义的变量 - strategy pattern - returning an undefined variable on php

strategy pattern - returning an undefined variable on php

下面的代码(取自以下葡萄牙语页面http://br.phptherightway.com/pages/Design-Patterns.html)展示了策略的使用。我的问题是如何从ArrayOutput加载()方法可以返回$arrayOfData，如果它没有定义?

interface OutputInterface{
    public function load();
}
class ArrayOutput implements OutputInterface{
    public function load()    {
        return $arrayOfData;
    }
}
class SomeClient{
    private $output;
    public function setOutput(OutputInterface $outputType){
        $this->output = $outputType;
    }
    public function loadOutput(){
        return $this->output->load();
    }
}
$client = new SomeClient();
// Array
$client->setOutput(new ArrayOutput());
$data = $client->loadOutput();

请看下面的代码

interface OutputInterface{
    public function load();
}
class ArrayOutput implements OutputInterface{
    public function load()    {
        if (empty ($arrayOfData))
        {
           return null;  //if the $arrayOfData is empty then it will return an empty response i.e null
        }
        return $arrayOfData;
    }
}
class SomeClient{
    private $output;
    public function setOutput(OutputInterface $outputType){
        $this->output = $outputType;
    }
    public function loadOutput(){
        return $this->output->load();
    }
}
$client = new SomeClient();
// Array
$client->setOutput(new ArrayOutput());
$data = $client->loadOutput();

不能。这里的代码看起来更像是让您了解如何实现该模式的东西。它应该是这样的:

interface OutputInterface {
    public function load();
}
class ArrayOutput implements OutputInterface {
    private $arrayOfData;
    function __construct($array) {
        $this->arrayOfData = $array;
    }
    public function load()    {
        return $this->arrayOfData;
    }
}