c# - 如何从 Expression> 获取接口(interface)成员名称

Question

我正在寻找一种方法来获取传递给 Client.SendMessage 的表达式的接口(interface)成员名称。下面是我尝试过的，但我得到了一个无效的转换异常。

public interface IFoo
{
    void Operation1(object data);
    void Operation2(object data);
}

public class FooClient<T>
{
    public void SendMessage(Expression<Action<T>> expr)
    {
        // InvalidCastException:
        // Cannot cast 'InstanceMethodCallExpressionN' to 'MemberExpression'
        var iMemberName = ((MemberExpression)expr.Body).Member.Name;

        Console.WriteLine(iMemberName);
    }
}

class Program
{
    static void Main()
    {
        var client = new FooClient<IFoo>();

        // Should write 'Operation1'
        client.SendMessage(x => x.Operation1("Hello, world!"));

        // Should write 'Operation2'
        client.SendMessage(x => x.Operation2("How are you?"));
    }
}

Answer 1

因为内部表达式是 MethodCallExpression (而不是代表属性或字段访问表达式的 MemberExpression)，您应该适本地转换它并获取 Method property 返回的 MethodInfo 对象的名称。 .

public class FooClient<T>
{
    public void SendMessage(Expression<Action<T>> expr)
    {
        var iMemberName = ((MethodCallExpression)expr.Body).Method.Name;

        Console.WriteLine(iMemberName);
    }
}