Question

我使用了一些代码来创建一些对象（比如DependencyProperty），它使用了一个Expression，所以我可以使用单个lamda检索属性名称和属性的返回类型

public static class DependencyPropertyOf<TOwner>
{
    public static IDependencyPropertyBuilder<TOwner, TProp> From<TProp>(Expression<Func<TOwner, TProp>> propSelected)
    {
        if (propSelected.Body is MemberExpression propExp && propExp.Member is PropertyInfo propInfo)
        {
            return new DependencyPropertyBuilder<TOwner, TProp>(propInfo.Name);
        }
        throw new ArgumentException("Specify a property in the expression");
    }
}

// Usage
public static readonly DependencyProperty SomethingProperty 
    = DependencyPropertyOf<MyClass>.From(myClass => myClass.Something);

我想做同样的事情，但是使用指向C＃事件的lambda，使用代码将是

public static readonly RoutedEvent HoveredEvent =
    RoutedEventOf<MyClass>.RegisterRoutedEvent(x => x.Hovered);

public event RoutedEventHandler Hovered
{
    add => this.AddHandler(HoveredEvent, value);
    remove => this.RemoveHandler(HoveredEvent, value);
}


public static class RoutedEventOf<TOwner>
{
    public static IRoutedEventBuilder<TOwner, TProp> From<TProp>(Expression<Func<TOwner, TProp>> propSelected)
    {
        if (propSelected.Body is MemberExpression propExp && propExp.Member is PropertyInfo propInfo)
        {
            return new RoutedEventBuilder<TOwner, TProp>(propInfo.Name);
        }
        throw new ArgumentException("Specify an event in the expression");
    }

    public static RoutedEvent RegisterRoutedEvent<TProp>(Expression<Func<TOwner, TProp>> propSelected, Action<IRoutedEventBuilder<TOwner, TProp>> callback = null)
    {
        var builder = RoutedEventOf<TOwner>.From(propSelected);
        callback?.Invoke(builder);
        return builder.RegisterRoutedEvent();
    }
}

但编译器抱怨The event 'MyClass.Hovered' can only appear on the left hand side of += or -=似乎非常敏感，因为编译器为我认为的事件做了很多额外的隐形工作。

所以我的问题是：有没有办法使用Expression＆lt;＆gt;在C＃中指定事件？

相关：Is it possible to target an EventHandler in a lambda expression?

编辑：添加了RoutedEventOf代码，到目前为止它与DependencyPropertyOf＆lt;＆gt;基本相同因为我找不到与https://referencesource.microsoft.com/#System.Core/Microsoft/Scripting/Ast/LambdaExpression.cs,51d6d604b8c53dc8

中的事件相关的内容

使用表达式<func，tprop =“”>来指定事件而不是属性

0 个答案: