php面对对象之延迟静态绑定：static关键字

先看一段代码：

abstract class domainObject{
static $name = 'domain';
public static function create(){
return self::$name;
}
}
class document extends domainObject{
static $name = 'document';
}
var_dump(document::create());

运行结果：string ‘domain’ (length=6)

self被解析为定义create()的domainObject，而不是解析为调用self的document类；

通过引入延迟静态绑定概念，将上述代码中父类的self:: 替换为static::，

abstract class domainObject{
static $name = 'domain';
public static function create(){
return static::$name;
}
}
class document extends domainObject{
static $name = 'document';
}
var_dump(document::create());

运行结果即为：string ‘document’ (length=8)

延迟静态绑定可使php在子类中查找所有的属性、值