从表达式树中提取方法名称

Question

我正在尝试实现以下模式函数：

MethodInfo GetMethod(      
  Expression<Func<TTarget, EventHandler<TEventArgs>>> method)

如果需要，我可以提供TTarget的实例

所需的用途是：

public static void Main(string[] args)
{
    var methodInfo = GetMethod<Program, EventArgs>(t => t.Method);
    Console.WriteLine("Hello, world!");
}
private void Method(object sender, EventArgs e)
{
}

以下是我迄今为止所尝试的：

private static MethodInfo GetMethod(TTarget target, Expression<Func<TTarget, EventHandler<TEventArgs>>> method)
{
  var lambda = method as LambdaExpression;
  var body = lambda.Body as UnaryExpression;
  var call = body.Operand as MethodCallExpression;
  var mInfo = call.Method as MethodInfo;
  Console.WriteLine(mInfo);
  throw new NotImplementedException();
}

打印出来：

System.Delegate CreateDelegate(System.Type, System.Object, System.Reflection.Met hodInfo)

Answer 1

您已经完成了一半。看看下面的代码

public static void Main(string[] args)
{
    var program = new Program();
    var methodInfo = GetMethod<Program, EventArgs>(()=> program.Method);
    Console.WriteLine(methodInfo.Name);
}

并使用以下代码获取方法名称。

static MethodInfo GetMethod<TTarget, TEventArgs>(Expression<Func<EventHandler<TEventArgs>>> method) where TEventArgs:EventArgs
{
    var convert = method.Body as UnaryExpression;
    var methodCall = (convert.Operand as MethodCallExpression);
    if (methodCall != null && methodCall.Arguments.Count>2 && methodCall.Arguments[2] is ConstantExpression)
    {
        var methodInfo = (methodCall.Arguments[2]as ConstantExpression).Value as MethodInfo;
        return methodInfo;
    }
    return null;
}

我希望这能回答你的问题。