属性 - 如何避免重复的代码 [英] Properties - how to avoid code repetition

问题描述

在创建将在视图模型被用于遵循MVVM模式的应用类，我要实现的属性是这样的：

When creating a class that will be used in a viewmodel for an application that follows the MVVM pattern, I have to implement properties this way:

private string _MyStringPropertyA;
public string MyStringPropertyA
{
    get {return _MyStringPropertyA;}
    set 
    {
        _MyStringPropertyA=value;
        OnPropertyChanged(()=>MyStringPropertyA);
    }
}


private string _MyStringPropertyB;
public string MyStringPropertyB
{
    get {return _MyStringPropertyB;}
    set 
    {
        _MyStringPropertyB=value;
        OnPropertyChanged(()=>MyStringPropertyB);
    }
}

而不是更简单

instead of the more simple

public string MyStringPropertyA {get;set;}
public string MyStringPropertyA {get;set;}

只是因为我必须提高对二传手的事件。除了使我的代码越长，我认为它有复制和粘贴程序的代码味道。我能做些什么来避免这种情况？是否有可能建立一个泛型类的样子，我不知道， MVVMEnabled< T> ，我可以实现为：

simply because I have to raise the event on the setter. Besides making my code longer, I think it has a code smell of copy-and-paste programming. What can I do to avoid this? Is it possible to construct a generic class like, I don't know, MVVMEnabled<T> which I can implement as:

public MVVMEnabled<string> MyStringPropertyA {get;set;}
public MVVMEnabled<string> MyStringPropertyB {get;set;}

，以便在通用类中的代码将确保OnPropertyChanged火灾当值设置？

so that the code in the generic class will ensure that the OnPropertyChanged fires when value is set?

推荐答案

我在哪里工作，我们做同样的东西你的 MVVMEnabled 建议，效果很好。

Where I work we do something similar to your MVVMEnabled suggestion and it works well.

要观看的唯一一件事是，在 MVVMEnabled 的属性的属性的值现在藏（值，例如），所以你最终获得一个稍微详细绑定表达式，如 {结合MyStringPropertyA.Value}

The only thing to watch for is that the value of the property is now tucked away in a property of MVVMEnabled (value, for example), so you end up with a slightly more verbose binding expression, such as {Binding MyStringPropertyA.Value}

要做到这一点有 MVVMEnabled 实现INotifyPropertyChanged。你需要的属性，比如值这是将（在您的示例字符串）进行管理的值：

To do this have MVVMEnabled implement INotifyPropertyChanged. You'll need a property, say Value which is the value that will be managed (a string in your example):

public T Value
{
  get{return m_Value;}
  set
  {
    if(m_Value != value)
    {
      m_Value = value;
      OnPropertyChanged(()=>Value);
    }
  }
}

在主类让你属性只读：

public MVVMEnabled<string> MyStringPropertyA {get;private set;}

和在构造函数初始化：

public SomeModel()
{
  this.MyStringPropertyA = new MVVMEnabled<string>();
}

它是只读的原因是因为你改变通过价值值属性，永不 MVVMEnabled 属性。

现在当你需要改变它做这样的事情：

Now, when you need to change it do something like this:

this.MyStringPropertyA.Value = "hello, world";

和只要你的绑定是这样的：

And as long as your binding is this:

{Binding MyStringPropertyA.Value}

您应该ok了。

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