Question

请允许我指出,我拥有像现在这样一位家长:

class A {

    private $property;

    public static function factory($arg) {
        $object = new A();
        $object->property = $arg;
        return $object;
    }

}

我愿以这种方式延长:

class B extends A {

    public static function factory() {
        return parent::factory( constant );
    }

}

当I do B:因果() 我收到了<代码>A的物体。如果我想要的是哪一种类型的标的? B。 <<>tong>I 不能改动A。

Answer 1

1st version

That s because you hardcoded the A class in the factory method.
In class A, instead of $object = new A() try (require Php 5.3):

$class_name = get_called_class();
$object = new $class_name;

get_called_class() "Gets the name of the class the static method is called in."

较短版本:

$object = new static();

2nd version (hardcoded parent class):

人工授精:

$parent = parent::factory($args);
$obj = new static();
$obj->setTimestamp($parent->getTimestamp());
$obj->setTimezone($parent->getTimezone());
return $obj;

或者使用黑板自动进行:

如何对待PHP中的 Cast

Answer 2

例如:

You have two classes (unleast)
both classes can be instantiated (concrete, not pure or abstract)
one class is a superclass of another
both classes are instantiated with a "factory" method
the "factory" method of a subclass can invoke the the "factory" method of the superclass
each "factory" method can have several type or count of parameters

<><>Problem>

我现在要注意:

class B extends A {

    public static function factory() {
        return parent::factory( constant );
    }

}

www.un.org/spanish/ecosoc 简讯和快速回答:

修改如下:

class B extends A {

    public static function factory() {
        return A::factory( constant );
    }

}

http://www.un.org。

你们试图压倒(和超载,有不同的参数)固定功能。

其共同错误假定固定方法是虚拟的,可以推翻。有些方案语言允许(Object Pascal, Delphi),其他非专利(C#, Java),PHP取决于版本,我想。

为了诚实起见,“法定职能”的工作类似于具有名称空间的全球职能,可公开接触某类成员,而不是使用方法。我建议将这些职能视为全球职能,始终如此。

Cheers.

1st version

2nd version (hardcoded parent class):

友情链接