anchor.diff:    Learn about them in the [Structural Directives](structural-directives.html) guide.
   
     *结构型*指令修改视图的结构。例如，[NgFor](template-syntax.html#ngFor) 和 [NgIf](template-syntax.html#ngIf)。
  +  要了解更多，参见[结构型指令](structural-directives.html) guide。
   
     *Attribute directives* are used as attributes of elements.
     The built-in [NgStyle](template-syntax.html#ngStyle) directive in the 
  
positive.code: +makeExcerpt('src/app/app.component.ts', 'class', '')
  
  :marked
    Here are the harness and directive in action.下面是测试程序和指令的动图。
  figure.image-display
    img(src="/resources/images/devguide/attribute-directives/highlight-directive-v2-anim.gif" alt="Highlight v.2")
  
  
negative.code:   They are _private_ from an Angular binding perspective.
    When adorned with the `@Input` decorator, the property becomes _public_ from an Angular binding perspective.
    Only then can it be bound by some other component or directive.
    
    但组件或指令不应该盲目的信任其它组件或指令。
    因此组件或指令的属性默认是不能被绑定的。
    从Angular绑定机制的角度来看，它们是*私有*的，而当添加了`@Input`时，它们变成了*公共*的
    只有这样，它们才能被其它组件或属性绑定。
    
    You can tell if `@Input` is needed by the position of the property name in a binding.
    
    你可以根据属性名在绑定中出现的位置来判定是否要加`@Input`。
  