Question

对于我使用Xamarin.Forms编写的应用程序，我使用Result对象，因此在查询服务器端代码时可以处理正面和负面结果：

namespace GenerationLondon
{
    public abstract class Result<E, S>
    {
        private Result() {}

        public abstract R fold<R>(Func<E, R> left, Func<S, R> right);

        public abstract void consume (Action<E> left, Action<S> right);

        public static Result<E, S> success(S value)
        {
            return new Success (value);
        }

        public static Result<E, S> error(E value)
        {
            return new Error (value);
        }

        public class Success : Result<E, S>
        {
            private S success;

            public Success(S success)
            {
                this.success = success;
            }

            public override R fold<R> (Func<E, R> left, Func<S, R> right)
            {
                return right.Invoke(success);
            }

            public override void consume (Action<E> left, Action<S> right)
            {
                right.Invoke (success);
            }
        }

        public class Error : Result<E, S>
        {
            private E error;

            public Error(E error)
            {
                this.error = error;
            }

            public override R fold<R> (Func<E, R> left, Func<S, R> right)
            {
                return left.Invoke (error);
            }

            public override void consume (Action<E> left, Action<S> right)
            {
                left.Invoke (error);
            }
        }
    }
}

用户成功登录后，我向服务器发出2个请求以收集一些信息，但我一直收到以下异常：

System.InvalidProgramException: Invalid IL code in GenerationLondon.LoginPage/<OnLogin>c__asyncD/<OnLogin>c__AnonStorey14:<>m__1 (System.Collections.Generic.List`1<GenerationLondon.UserEvent>): IL_0008: stfld     0x040000ef


  at GenerationLondon.Result`2+Success[System.String,System.Collections.Generic.List`1[GenerationLondon.UserEvent]].consume (System.Action`1 left, System.Action`1 right) [0x00008] in /Users/tom/Documents/workspace/GenerationLondon/GenerationLondon/Result.cs:39
  at GenerationLondon.LoginPage+<OnLogin>c__asyncD.MoveNext () [0x001df] in /Users/tom/Documents/workspace/GenerationLondon/GenerationLondon/Views/LoginPage.xaml.cs:30
  at --- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/2320/1f068b49/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (System.Object state) [0x00000] in /Users/builder/data/lanes/2320/1f068b49/source/maccore/_build/Library/Frameworks/Xamarin.iOS.framework/Versions/git/src/mono/external/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1006
  at UIKit.UIKitSynchronizationContext+<Post>c__AnonStorey0.<>m__0 () [0x00000] in /Users/builder/data/lanes/2320/1f068b49/source/maccore/src/UIKit/UIKitSynchronizationContext.cs:24
  at Foundation.NSAsyncActionDispatcher.Apply () [0x00000] in /Users/builder/data/lanes/2320/1f068b49/source/maccore/src/Foundation/NSAction.cs:163
  at at (wrapper managed-to-native) UIKit.UIApplication:UIApplicationMain (int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, IntPtr principal, IntPtr delegate) [0x00005] in /Users/builder/data/lanes/2320/1f068b49/source/maccore/src/UIKit/UIApplication.cs:77
  at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x00038] in /Users/builder/data/lanes/2320/1f068b49/source/maccore/src/UIKit/UIApplication.cs:61
  at GenerationLondon.iOS.Application.Main (System.String[] args) [0x00008] in enter code here/Users/tom/Documents/workspace/GenerationLondon/iOS/Main.cs:17
    enter code here

有问题的代码如下：

result.consume(async () => {
                Result<string, Details> detailsResult = await restService.getDetails ();
                Result<string, List<Event>> eventsResult = await restService.getEvents();
                eventsResult.consume(async error => await DisplayAlert("Problem communicating with the server", error, "Ok"), events => {
                    detailsResult.consume(async error => await DisplayAlert("Problem communicating with the server", error, "Ok"), details => {
                        loginManager.ShowMainPage (details, events);
                    });
                });
            }, async error => await DisplayAlert("Login Issue", error, "Ok"));

单独运行时代码可以正常运行，但在iOS模拟器上引入detailsResult后尝试处理eventsResult时会出现此异常。两个调用都成功返回，异常本身来自return right.Invoke(success);我唯一能想到的是Mono遇到了类型问题。

有什么想法吗？

Xamarin.Forms InvalidProgramException System.InvalidProgramException：无效的IL代码

0 个答案: