PHP 可以用 static:: 替换 self:: 吗？
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PHP Can static:: replace self::?
提问by elite5472
I am a little confused with this matter. I am designing an ORM class that tries to behave very similarly to ActiveRecord in ruby on rails, but that's beside the point.
我对这个问题有点困惑。我正在设计一个 ORM 类，该类的行为与 ruby on rails 中的 ActiveRecord 非常相似，但这不是重点。
What I'm trying to say is that my class makes extensive use of static attribute inheritance, specially for database and table handling. My question is, should I use self:: at all?
我想说的是，我的类广泛使用了静态属性继承，特别是用于数据库和表处理。我的问题是，我应该使用 self:: 吗？
回答by DarkThrone
You have to ask yourself: "Am I targeting the problem with the adequated approach?"
您必须问自己：“我是否使用适当的方法针对问题？”
self::and static::do two different things. For instance self::or __CLASS__are references to the current class, so defined in certain scope it will NOT suffice the need of static calling on forward.
self::并static::做两件不同的事情。例如self::or__CLASS__是对当前类的引用，因此在某些范围内定义它不足以满足静态调用转发的需要。
What will happen on inheritance?
继承会发生什么？
class A {
public static function className(){
echo __CLASS__;
}
public static function test(){
self::className();
}
}
class B extends A{
public static function className(){
echo __CLASS__;
}
}
B::test();
This will print
这将打印
A
In the other hand with static::It has the expected behaviour
另一方面，static::它具有预期的行为
class A {
public static function className(){
echo __CLASS__;
}
public static function test(){
static::className();
}
}
class B extends A{
public static function className(){
echo __CLASS__;
}
}
B::test();
This will print
这将打印
B
That is called late static bindingin PHP 5.3.0. It solves the limitation of calling the class that was referenced at runtime.
这在 PHP 5.3.0 中称为后期静态绑定。它解决了在运行时调用被引用的类的限制。
With that in mind I think you can now see and solve the problem adequately. If you are inheriting several static members and need access to the parent and child members self::will not suffice.
考虑到这一点，我认为您现在可以充分了解并解决问题。如果您继承了多个静态成员并且需要访问父成员和子成员是self::不够的。
回答by Radouane FADEL
try to use the code bellow to see the difference between selfand static:
尝试使用下面的代码来查看self和static之间的区别：
<?php
class Parent_{
protected static $x = "parent";
public static function makeTest(){
echo "self => ".self::$x."<br>";
echo "static => ".static::$x;
}
}
class Child_ extends Parent_{
protected static $x = "child";
}
echo "<h4>using the Parent_ class</h4>";
Parent_::makeTest();
echo "<br><h4>using the Child_ class</h4>";
Child_::makeTest();
?>
and you get this result:
你会得到这个结果：
using the Parent_ class
- self => parent
- static => parent
using the Child_ class
- self => parent
- static => child
使用 Parent_ 类
- 自己 => 父母
- 静态 => 父
使用 Child_ 类
- 自己 => 父母
- 静态 => 孩子
