每个孩子课程一次执行方法

Question

我试图通过使用晚期静态绑定来执行每个类的initialize()方法：

class BaseClass 
{   
    protected static $initialized = false;
    public static function find()
    {
        static::initialize();
        //TODO search entries and return as instances...
    }
    protected static function initialize() 
    {
        if (static::$initialized) 
            return;
        echo 'Initializing ', static::class, '<br/>';
        //do important stuff
        static::$initialized = true;
    }
}
class Child1 extends BaseClass {}
class Child2 extends BaseClass {}

$initialized属性在扩展类中共享。

Child1::find(); //Outputs 'Initializing Child1', as expected
Child2::find(); //Doesn't execute 'initialize()' because 
                //$initialized property was set to true by Child1
                //Expected: 'Initializing Child2'

有什么简单的方法可以实现它吗？

Answer 1

您可以使用类名称为密钥来更改$初始化为数组(如注释中的建议(：

class BaseClass 
{   
    protected static $initialized = [];
    public static function find()
    {
        return static::initialize();
    }
    protected static function initialize() 
    {
        $class_name = static::class;
        if (!empty(static::$initialized[$class_name])) { 
            return static::$initialized[$class_name];
        }
        echo 'Initializing ', $class_name, '<br/>';
        //do important stuff
        static::$initialized[$class_name] = new static();
        // do another important stuff and return instance
        return static::$initialized[$class_name];
    }
}
class Child1 extends BaseClass {}
class Child2 extends BaseClass {}