为什么属性不是接口中的声明

In Actionscript 3 I can't declare vars in Interfaces. I don't get it. I know i can work this around by defining getters and setters, but what if i just want a simple public property? I usually use getters and setters if there is something to do when i set or get a property, but what if i just want to store a value?In Actionscript 3 I can't declare vars in Inter