何时在新类名后添加括号？ [英] When to add brackets after new class name?

问题描述

可能重复：

PHP类实例化。要使用还是不使用括号？

省略括号和无参数的对象构造函数

没有括号，新类似乎没有打扰。所以，我怀疑括号（）的用法是什么。我搜索php手册，没有得到它。

With or without the brackets, the new Class seems not bother. So, I doubt what's the usage of the brackets (). I searched php manual, didn't get it. Could anybody explain?

推荐答案

括号的目的是让你输入你的构造函数可以接受的任何参数。

The purpose of the brackets is for you to enter any arguments that your constructor may accept.

class Example{

    private $str;

    public function __construct($str){
        $this->str = $str;
    }

    public function output(){
        echo $this->str;
    }

}

$ex = new Example; // missing argument error
$ex = new Example('Something');
$ex->output(); // echos "Something"

如果你的类构造函数不接受任何参数，出来。为了好代码，我总是保持括号，无论构造函数是否接受任何参数。

If your class constructor does not accept any arguments, you may leave the brackets out. For good code sake, I always keep the brackets, whether or not the constructor accepts any argument.

大多数来自C＃或Java背景的编码人员都会保留括号，因为它们与他们更为相似。

Most coders coming from C# or Java background would keep the parenthesis as it is more familar to them.

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