简单的小INotifyPropertyChanged实现 [英] Simple small INotifyPropertyChanged implementation

问题描述

说我有以下课程:

public MainFormViewModel
{
    public String StatusText {get; set;}
}

将对StatusText的更改反映到与其绑定的任何控件中，最简单的最小方法是什么?

What is the easiest smallest way to get my changes to StatusText to reflect to any controls that bind to it?

很明显，我需要使用INotifyPropertyChanged，但是有没有一种很酷的方法来使我的代码不混乱?需要大量文件?等等?

Obviously I need to use INotifyPropertyChanged, but is there a cool way to do it that does not clutter up my code? need lots of files? etc?

注意:如果这是骗子，那么我很抱歉.我进行了搜索，但没有找到任何东西，只是使用了 T4代码生成听起来不容易(至少要设置).

Note: If this is a dupe then I am sorry. I searched and could not find any thing but using T4 code Generation which does not sound easy (to setup at least).

推荐答案

不幸的是，C#没有提供一种简单的机制来自动执行此操作...它已经

Unfortunately C# doesn't offer an easy mechanism to do that automatically... It has been suggested to create a new syntax like this :

public observable int Foo { get; set; }

但我怀疑它是否会包含在该语言中...

But I doubt it will ever be included in the language...

一种可能的解决方案是使用AOP框架，例如 Postsharp ，那样，您只需要装饰自己的属性的属性:

A possible solution would to use an AOP framework like Postsharp, that way you just need to decorate your properties with an attribute:

public MainFormViewModel : INotifyPropertyChanged
{
    [NotifyPropertyChanged]
    public String StatusText {get; set;}
}

(还没有尝试过，但是我很确定Postsharp允许您做这种事情...)

(haven't tried, but I'm pretty sure Postsharp allows you to do that kind of thing...)

更新:好的，我设法使其工作.请注意，这是一个非常粗糙的实现，在私有字段上使用反射来检索委托...当然可以改进，但我将其留给您;)

UPDATE: OK, I managed to make it work. Note that it's a very crude implementation, using reflection on a private field to retrieve the delegate... It could certainly be improved, but I'll leave it to you ;)

[Serializable]
public class NotifyPropertyChangedAttribute : LocationInterceptionAspect
{
    public override void OnSetValue(LocationInterceptionArgs args)
    {
        object oldValue = args.GetCurrentValue();
        object newValue = args.Value;
        base.OnSetValue(args);
        if (args.Instance is INotifyPropertyChanged)
        {
            if (!Equals(oldValue, newValue))
            {
                RaisePropertyChanged(args.Instance, args.LocationName);
            }
        }
    }

    private void RaisePropertyChanged(object instance, string propertyName)
    {
        PropertyChangedEventHandler handler = GetPropertyChangedHandler(instance);
        if (handler != null)
            handler(instance, new PropertyChangedEventArgs(propertyName));
    }

    private PropertyChangedEventHandler GetPropertyChangedHandler(object instance)
    {
        Type type = instance.GetType().GetEvent("PropertyChanged").DeclaringType;
        FieldInfo propertyChanged = type.GetField("PropertyChanged",
                                                  BindingFlags.Instance | BindingFlags.NonPublic);
        if (propertyChanged != null)
            return propertyChanged.GetValue(instance) as PropertyChangedEventHandler;

        return null;
    }
}

请注意，您的类仍需要实现INotifyPropertyChanged接口.您只是不必在属性设置器中显式引发该事件.

Note that your class still need to implement the INotifyPropertyChanged interface. You just don't have to explicitly raise the event in your property setters.

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