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类成员对象的访问常量不起作用

[英]Access constant of a class member object doesn't work

if I try the following example (PHP 5.4) I get the following error: 如果我尝试以下示例(PHP 5.4),则会收到以下错误:

Parse error: syntax error, unexpected '::' (T_PAAMAYIM_NEKUDOTAYIM), expecting ',' or ';' 解析错误:语法错误,意外的'::'(T_PAAMAYIM_NEKUDOTAYIM),期望为','或';'

class a {
    public $p;
    public function __construct() {
        $this->p = new b;
    }
    public function giveout() {
        echo $this->p::c;
    }
}
class b {
    const c = '234';
}
$obj = new a;
$obj->giveout();

But why? 但为什么? Isn't it possible to use the double colon and arrow in one expression? 一个表达式中不能使用双冒号和箭头吗? I know I could also use a getter method in class b and then call $this->p->get() , but I'd rather like to use the above syntax. 我知道我也可以在类b中使用getter方法,然后调用$this->p->get() ,但是我想使用上面的语法。

Rewrite 改写

echo $this->p::c;

to

echo $this->p=b::c;

and.. 和..

$a->giveout();

to

$obj->giveout();


Putting it all together... 全部放在一起...

<?php
class a {
public $p;
public function __construct() {
$this->p = new b;
}
public function giveout() {
echo $this->p=b::c;
}
}
class b {
const c = '234';
}
$obj = new a;
$obj->giveout();

OUTPUT : 输出:

234

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