AS3：类型为SimpleButton的全局变量更改为DisplayObject的未知原因，不会让我访问.upState.textColor！

问题描述

这是一个问题，最好在代码中解释。

This is a problem that's best explained in code.

我没有看到 active_button.upState ，我知道是一个TextField当我尝试访问 textColor 属性时，神奇地变成一个DisplayObject。

I don't see how active_button.upState, which I know is a TextField (see trace statements), mysteriously turns into a DisplayObject when I try to access the textColor property.

另外，为什么我有一个对象，我知道是一个SimpleButton（再次，看到跟踪）我需要把它转换到SimpleButton顺序把它存储在var？这对我没有任何意义。

Also, why is it that when I have an object that I know is a SimpleButton (again, see traces) I need to cast it to SimpleButton in order to store it in a var? That doesn't make any sense to me.

所有的帮助是非常感谢。感谢。

All help is much appreciated. Thanks.

public class Menu extends MovieClip
{
    private var active_button:SimpleButton;

    public function Menu() 
    {
        // menu_list is a collection of SimpleButtons, I make the first one the 'active_button' and give each a MOUSE_DOWN event listener.
        trace( menu_list.getChildAt( 0 )); // writes [object SimpleButton]
        active_button = SimpleButton( menu_list.getChildAt( 0 )); // Cast is required here. Otherwise throws Error 1118. Strange. Why is that?

        for( var i:Number = 0; i < menu_list.numChildren; i++ )
        {
            menu_list.getChildAt( i ).addEventListener( MouseEvent.MOUSE_DOWN, menuClick );
        }
    }

    private function menuClick( e:Event ) : void
    {
        trace( e.target ); // writes [object SimpleButton]
        active_button = SimpleButton( e.target ); // Cast is required here. Otherwise throws Error 1118. Still Strange.
        trace( active_button ); // writes [object SimpleButton]. Normal.
        trace( active_button.upState ); // writes [object TextField]. Normal.
        active_button.upState.textColor = 0xAAAAAA; // Throws Error 1119. WTF?! textColor is a perfectly valid property of active_button.upState. Why is it suddenly type DisplayObject?
    }
}

错误：

1118：静态类型的隐式强制值flash.display：DisplayObject到可能不相关的类型flash.display：SimpleButton。

1118: Implicit coercion of a value with static type flash.display:DisplayObject to a possibly unrelated type flash.display:SimpleButton.

1119：Access可能未定义的属性textColor通过静态类型的引用flash.display：DisplayObject

1119: Access of possibly undefined property textColor through a reference with static type flash.display:DisplayObject

编辑：我已经压缩了我的问题，并发布为

I've condensed my question a little bit and posted as AS3: Why does datatype automatically change from TextField to DisplayObject on its own?

推荐答案

从显示列表中提取的任何东西都被归类为最低可能的dinominator ，因为虽然SimpleButton是一个displayObject，不是所有的displayObjects都将是SimpleButtons。
这可能是你的第二个问题的原因，只是执行稍有不同。在SimpleButton中有一个直接引用，说明upState是一个TextField？

Anything that is pulled from the displaylist is classed as the lowest possible dinominator (eg. displayObject), as although SimpleButton is a displayObject, not all displayObjects will be SimpleButtons.This is probably the reason for your second problem too, just slightly different in execution. is there a direct reference in SimpleButton that states upState is a TextField?

尝试关闭严格的编译模式，看看它是否有帮助。
请参阅 for more information

try switching off Strict Mode of compilation and see if it helps.see Type Checking Livedocs for more information

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