Make DateTime :: createFromFormat（）返回子类而不是父类 [英] Make DateTime::createFromFormat() return child class instead of parent

问题描述

我正在扩展 DateTime 添加一些有用的方法和常量。

I'm extending DateTime do add some useful methods and constants.

当使用新建创建新对象时，一切都很好，但使用静态方法 createFromFormat 它总是返回原始的 DateTime 对象，当然没有一个子方法可用。

When using new to create a new object everything is fine but when using the static method createFromFormat it always returns the original DateTime object and of course none of the child methods are available.

我正在使用以下代码来规避此问题。这是最好的方法吗？

I am using the following code to circumvent this issue. Is this the best approach?

namespace NoiseLabs\DateTime;

class DateTime extends \DateTime
{
    static public function createFromFormat($format, $time)
    {
        $ext_dt = new self();

        $ext_dt->setTimestamp(parent::createFromFormat($format, time)->getTimestamp());

        return $ext_dt;
    }
}

推荐答案

是要走的路然而，由于你想要做的是渲染DateTime类可扩展性，建议您使用 static 而不是 self ：

This is the way to go. However, since what seems you want to do is to render the DateTime class extensible, I'd suggest you use static instead of self:

namespace NoiseLabs\DateTime;

class DateTime extends \DateTime
{
    static public function createFromFormat($format, $time)
    {
        $ext_dt = new static();
        $ext_dt->setTimestamp(parent::createFromFormat($format, $time)->getTimestamp());
        return $ext_dt;
    }
}

如果您不打算延长该课程，但如果有人曾经做过，这将阻止他再次做同样的解决方法。

It's not necessary if you don't plan on extending the class, but if someone ever does, it will prevent him from having to do the same workaround again.

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