isset 无法确定属性是否存在 [英] isset not able to determine if property exists

问题描述

我尝试使用 isset() 来确定此属性是否包含某些内容.我运行以下检查:

I tried to use isset() to determine if this property contains something. I run the following checks:

首先，我确定 $property->property_address 是否包含某些内容:

First, I determine if $property->property_address contains something:

var_dump($property->property_address);
// Outputs
// string(5) "hello"

现在，如果我在 isset() 中尝试:

Now if I try it in isset():

var_dump(isset($property->property_address));
// Outputs
// bool(false)

这是为什么?这就是为什么它不会在我的 if-else 上继续，因为 isset 返回 false.

Why is that? That is why it won'r proceed on my if-else, because isset returns false.

推荐答案

这是您重现这种确切行为的方式:

This is how you reproduce this exact behaviour:

<?php
class Shoop {
    public $actual = 'hello';
    public $mystery = array();

    public function __set($name, $value) {
        $this->mystery[$name] = $value;
    }
    public function __get($name) {
        if(isset($this->mystery[$name])) {
            return $this->mystery[$name];
        } else { return null; }
    }
}

$woop = new Shoop();
echo $woop->actual . "\n";

$woop->fake = 'da' . "\n";
echo $woop->fake;

var_dump(isset($woop->fake));

输出:

hello
da
bool(false)

然后你用:

public function __isset($name) {
    return isset($this->mystery[$name]);
}

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