使用 - >静态函数

Hi I'm a bit of a newbie to OOP, i just have a quick question: say I have a function in a class declared as

class House
{
    public static function hasAlcohol() 
    {
        // Do Something
    }
}

I know i can call this as

House::hasAlcohol()

However, i would also like to know if its okay with coding standards and PHP and if it would be error free to call hasAlcohol() from an instance of house (i tried it and got no errors), for example

$house = new House();
$house->hasAlcohol();

As this has caused several problems for me in the past: Yes, it is valid code. Should you do it? No. It gives the impression that the call is non-static and will most likely cause grief for people working on your code later on. There is no reason to make your code ambiguous.

This used to be possible, but the latest versions of PHP will throw an error, if I remember correctly. You should call static functions statically. You can do $house::hasAlcohol() though.

On a side note, should hasAlcohol really be static? From the name it appears it should be an instance method.

A more recommended pattern if you need constant access to a method is to use a static constructor and get an instance (even if it's a "blank" or "empty") instance to that class. So in the example you've shown, it might be better to have a method like this:

class House
{
    public function instance()
    {
        return new House; 
    }

    public function hasAlcohol() 
    {
        // Do Something
    }
}

Then if you ever needed to make a call to "hasAlcohol()" where you don't need an instance for any other purpose, you can do a one-off like so:

House::instance()->hasAlcohol();

or you can instantiate it like in your example:

$house = new House;
$house->hasAlcohol();

or, better yet, use your new factory method:

$house = House::instance();
$house->hasAlcohol();