actionscript-3 - 在 ActionScript 中，虚拟关键字有什么作用？

Question

我发现一些将virtual关键字用于函数的代码，例如:

package tryOut{
    public class Parent {

        public function Parent() {}

        public function foo():void{
            trace("Parent foo");
        }//foo

        public virtual function bar():void{
            trace("Parent virtual bar");
        }//bar      
    }//class
}//package

据我了解，使用virtual关键字应该修改覆盖方法的工作方式，或者使用子方法的工作方式，等等。但是似乎它什么也没做。具有扩展性:

package tryOut {
    public class Child extends Parent {
        public function Child() {}

        public override function foo():void {
            trace("Child foo");
        }//foo

        public override function bar():void {
            trace("Child virtual bar");
        }//bar

    }//class
}//package

打印以下代码:

var parent:Parent = new Parent();
var child:Child = new Child();

parent.foo(); //Parent foo
child.foo(); //Child foo
parent.bar(); //Parent virtual bar
child.bar(); //Child virtual bar

var childCast:Parent = child as Parent;

parent.foo(); //Parent foo
childCast.foo(); //Child foo
parent.bar(); //Parent virtual bar
childCast.bar(); //Child virtual bar

因此，这两种方法在覆盖方面的作用相同。 virtual关键字是否会更改我所缺少的内容？

Answer 1

从帮助文档中(如果您使用的是Flash，请搜索“虚拟”):

There are also several identifiers that are sometimes referred to as future reserved words. These identifiers are not reserved by ActionScript 3.0, though some of them may be treated as keywords by software that incorporates ActionScript 3.0. You might be able to use many of these identifiers in your code, but Adobe recommends that you do not use them because they may appear as keywords in a subsequent version of the language.

abstract boolean byte cast

char debugger double enum

export float goto intrinsic

long prototype short synchronized

throws to transient type

virtual volatile

因此，在AS3中，虚拟绝对不执行任何操作。