Dart中的重复类 [英] Duplicate Class in Dart

问题描述

我在写一个简单的应用程序来学习一些基本的Dart编程，但是我不能解决结构和包含 - 我得到一个复制类Point

all，我有我的主类我叫 MouseTrack 。它初始化列表，并有一个循环。

  import（'dart：html'）; 
 #import（'Eye.dart'）; 
 
 class MouseTrace {
 List< Eye>眼睛; 
 ... 
} 
  

其次， > Eye ，它应该将眼睛的信息保持为圆形。很简单：

  #library（'app：eye'）; 
 
 #import（'dart：html'）; //没有这个，我没有错误，但我想让它使用CanvasRenderingContext2D 
 
 #import（'Point.dart'）; 
 
 class Eye {
点位置; 
 num radius; 
 
 Eye（）：
 position = new Point（）{
} 
 
 void draw（CanvasRenderingContext2D context）{
 //一个圆
} 
} 
  

最后 >：

  #library（'app：point'）; 
 
 class Point {
 num x，y; 
 
 Point（this.x，this.y）; 
} 
  

我想要实现的是3个单独的类 - main ， ，因此我可以在 模型）和点中的点（用于存储位置）的实例。至少这是我习惯了。

PS我知道我可以跳过类型，但我想要它在那里，我想这是一个问题，包括而不是语言（并希望修复它，所以我知道如何做它正确）。
P.S.S.我已经切断了一些代码，所以你不必读取一切，但如果你想，我会发布所有。

解决方案

问题出在 app：eye 库（在 Eye.dart 文件中）。您导入 dart：html 和 app：point 库，但它们都定义了 类。此情况无效。你可以通过不导入 dart：html ，如果你不需要它，或者为这些导入之一加上前缀来解决它：

  #import（'dart：html'，prefix：'html'）; 
 #import（'Point.dart'）; 
  

在这种情况下，您必须引用 dart：html ，使用 html。前缀。在你的情况下，如果你想使用 CanvasRenderingContext2D 类，你将不得不写 html.CanvasRenderingContext2D 。 / p>

I am writing a simple application to learn some basic Dart programming but I can't work out the structure and inclusions - I get a Duplicate class Point

First of all, I have my main class I called MouseTrack. It initializes the list and will have a loop.

#import('dart:html');
#import('Eye.dart');

class MouseTrace {
List<Eye> eyes;
...
}

Secondly, I have a class called Eye, which is supposed to hold information of of an eye as a circle. It's quite simple:

#library('app:eye');

#import('dart:html'); // without this one, I get no error but I want to have it to use CanvasRenderingContext2D

#import('Point.dart');

class Eye {
  Point position;
  num radius;

  Eye() :
      position = new Point() {
  }

  void draw(CanvasRenderingContext2D context) {
    // draws a circle
  }
}

And finally Point:

#library('app:point');

class Point {
    num x, y;

    Point(this.x, this.y);
}

What I want to achieve is 3 separate classes - main, Eye and Point, so I can have instances of Eye in main (for simplicity & nice model) and instances of Point in Eye (for storing position). At least that's how I'm used to doing.

P.S I know I can skip types but I want it there and I guess it's a problem with inclusions rather than the language (and want to fix it so I know how to do it properly). P.S.S. I have cut off some code so that you don't have to read everything but, if you want, I will post it all.

解决方案

Problem lies in the app:eye library (in the Eye.dart file). You import dart:html and app:point libraries, but both of them define a Point class. This situation is invalid. You can solve it either by not importing dart:html at all, if you don't need it, or prefixing one of those imports:

#import('dart:html', prefix: 'html');
#import('Point.dart');

In this case, you will have to refer to names from dart:html by using a html. prefix. In your case, if you want to use the CanvasRenderingContext2D class, you will have to write html.CanvasRenderingContext2D instead.

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