[转]PHP5.3_延迟静态绑定_static

From : http://my.oschina.net/liuhui1990/blog/38611

基于PHP版本: 5.3.5

PHP5.3 以后引入了延迟静态绑定:

static(关键字) 类似于 self(关键字) , 但它指向的是被调用的类(Document) 而不是包含类(DomainObject), static 和 self 的区别:

<?php
class DomainObject{
    public static function createStatic(){
        return new static();        
    }
    public static function createSelf(){
        return new self();
    }
}

class User extends DomainObject{
    
}

class Document extends DomainObject{
    
}

echo '<pre>';
var_dump( Document::createStatic());
var_dump( Document::createSelf());

Result :

object(Document)[1]
object(DomainObject)[1]

以前你这么写:

abstract class DomainObject{

}

class User extends DomainObject{
    public static function create(){
        return new User();
    }
}

class Document extends DomainObject{
    public static function create(){
        return new Document();
    }
}

现在, 你可以这么写: 

abstract class DomainObject{
    public static function create(){
        return new static();
    }
}

class User extends DomainObject{

}

class Document extends DomainObject{

}

好处: 可以节省大量重复代码~