从基础开始深入学Flash AS3教程(7)(译文)

package {
    class MyClass {
        function MyClass() {
            var helper:MyHelper = new MyHelper();
        }
    }
}
class MyHelper {
    function MyHelper() {
        var helper:HelpersHelper = new HelpersHelper();
    }
}
class HelpersHelper {
    function HelpersHelper () {
    }
}

public
protected
private
internal (默认)

package {
    
    import flash.display.Sprite;
    
    // 应用类必须定义成public (默认是internal)
    public class AccessControl extends Sprite {
        
        // 构造器总是public的
        function AccessControl() {
            
            // 只有在这个文件中才能访问辅助类
            var helper:Helper = new Helper();
            
            trace(helper.pubNum); // OK
            // trace(helper.protNum); // Error - 错误，不能访问protected成员
            // trace(helper.privNum); // Error - 错误，不能访问private成员
            trace(helper.interNum); // OK
        }
    }
}
// 辅助类默认是internal
class Helper {
    
    // public声明允许在任何地方被访问
    // 变量通常被设置为private的，然后通过声明public的get set方法来访问
    public var pubNum:Number = 1;
    
    // protected声明只允许在子类中被访问
    protected var protNum:Number = 2;
    
    // private声明只能在类内部被访问
    private var privNum:Number = 3;
    
    // internal声明只允许在同一个包中被访问
    // 但是对于辅助类来说，只能在同一个文件类被访问
    internal var interNum:Number = 4;
        
    // 构造器永远都是public的
    function Helper() {
    }
}

package {
    
    import flash.display.Sprite;
    import containers.*;
    
    // Application class needs to be public (internal by default)
    public class AccessControl extends Sprite {
        
        // constructors are always public
        function AccessControl() {
            
            // can access classes in other packages
            // only if public
            var bowl:Bowl = new Bowl(); // OK
            // var basket:Basket = new Basket(); // Error - cannot access internal
            
            trace(bowl.pubNum); // OK
            // trace(bowl.protNum); // Error - cannot access protected
            // trace(bowl.privNum); // Error - cannot access private
            // trace(bowl.interNum); // Error - cannot access internal
        }
    }
}
ActionScript Code:
package containers {
    // public class accessible anywhere
    public class Bowl {
        
        // public access granted anywhere
        public var pubNum:Number = 1;
        
        // protected access granted only for
        // subclasses in that class
        protected var protNum:Number = 2;
        
        // private access granted only in this class
        private var privNum:Number = 3;
        
        // internal access granted only in the same package
        internal var interNum:Number = 4;
            
        // constructors are always public
        function Bowl() {
            
            // can access inteneral classes if in same package
            var basket:Basket = new Basket();
            
            trace(basket.pubNum); // OK
            // trace(basket.protNum); // Error - cannot access protected
            // trace(basket.privNum); // Error - cannot access private
            trace(basket.interNum); // OK - same package
            
            // clone using public method
            var basketCopy:Basket = basket.clone();
        }
    }
}
ActionScript Code:
package containers {
    
    // interal only accessible
    // from other classes in package
    internal class Basket {
        
        // public access granted anywhere
        public var pubNum:Number = 1;
        
        // protected access granted only for
        // subclasses in that class
        protected var protNum:Number = 2;
        
        // private access granted only in this class
        private var privNum:Number = 3;
        
        // internal access granted only in the same package
        internal var interNum:Number = 4;
        
        // constructors are always public
        function Basket() {
        }
        
        // accessible anywhere as long as
        // referencing a Basket instance
        public function clone():Basket {
            var basket:Basket = new Basket();
            basket.pubNum = pubNum; // OK
            basket.protNum = protNum; // OK - same class
            basket.privNum = privNum; // OK - same class
            basket.interNum = interNum; // OK
            return basket;
        }
    }
}

DisplayObject
InteractiveObject
DisplayObjectContainer

package {
    import flash.display.DisplayObject;
    public class MyDisplay extends DisplayObject{
        public function MyDisplay (){
            // ERROR
        }
    }
}