使用私有静态方法

Question

I am trying to work out whether the private static method in the example below should be non-static. It is only concerned with the static properties of the class which leads me to believe it is okay as a static method. However, it is only invoked from a non-static method, which suggests it should be a non-static method too.

I understand when a public method should be static, but not when a private method should be static.

Thanks in advance for your advice!

<?php
class MyClass
{
    private static $initialized = false;
    private static $staticProperty1;
    private static $staticProperty2;
    private        $normalProperty1;

    public function __construct($normalProperty)
    {
        $this->normalProperty1 = $normalProperty;
    }

    public function doSomething()
    {
        self::initialize();
        // Now do some other stuff
    }

    private static function initialize()
    {
        if (!self::$initialized) {
            self::$staticProperty1 = 'Hello';
            self::$staticProperty2 = 'World';
            self::$initialized = true;
        }
    }
}

Answer 1

This is an interesting question. You want to know when a private function should be static. It has to be static if you want to call it from another static method. That is because you do not have access to $this.

My previous assumption was not correct. You can also call a non static method from a static function. But you have to consider that you do not have access to the object itself with the variable $this. Also it is not possible to access non static object properties.

In your example, in my opinion if you call the method from a non static context anyway, you can make it not static. There is no need for it to be static. But I cannot tell you if this is good practice. Just what I would do.