在WPF便携式类库ICommand的编译错误 - 不知道如何妥善解决这个？ [英] Portable Class Library ICommand compilation error in WPF -- Not sure how to resolve this appropriately?
问题描述
一些背景资料：
- 在我使用VS 2013
- 在我创建了一个可移植类库（目标：.NET 4.5 / Silverlight的5 /运电话8 /运店8）
- 在我实现了我的类名为
MyCommand的的ICommand接口。
MyCommand.cs：
公共类MyCommand：ICommand的
{
公共BOOL CanExecute（对象参数）
{
抛出新的NotImplementedException（）;
}
公共无效执行（对象参数）
{
抛出新的NotImplementedException（）;
}
公共事件的EventHandler CanExecuteChanged;
}
我发现，当我试图引用使用 MyCommand 类在WPF 4.5应用程序时，我收到以下错误：
类型System.Windows.Input.ICommand在装配定义 未引用。您必须添加一个引用组件 'System.Windows，版本= 2.0.5.0，文化=中立， 公钥= 7cec85d7bea7798e，重定目标=是。
我真的不知道为什么的这种情况正在发生，或者我能做些什么，以妥善解决它。冲刷互联网后，我发现答案在谈论我的WPF应用程序添加一个引用 System.Windows.dll中4.0.0.0 。这样做可以让我来编译和运行应用程序，但我的IDE抱怨说：
接口成员无效 System.Windows.Markup.IComponentConnector.Connect（在，对象）'不是 实现。
这会发生我MainWindow.cs类。有没有比一个更好的修正，只是处理这个错误，所以我不添加引用 System.Windows.dll中在一个WPF应用程序，它真的不需要它？我说，它并没有真正需要它，因为如果我复制/粘贴 MyCommand 类到WPF应用程序，它工作正常。它只有一个问题，因为我试图把它作为一个便携式类库。
更新：
似乎有更多的这种比满足眼睛。我创建了一个新的WPF应用程序和使用的NuGet引用MvvmCross解决方案（因为它有一个 MvxCommand ）对象。当我这样做，我得到了同样的错误。
大卫基恩的回答以一个类似的问题，表明，这应通过VS2012 / VS2013是固定的并且如果没有，只是重新安装/修复。我完全打消了我的VS安装，从头开始（VS2013），重新安装它，仍然有这个问题。所以，这是一个真正的错误还是我做错什么了吗？
更新2：
我尝试看看我是否能分配 MyCommand 类的一个实例的ICommand ：的ICommand CMD =新MyCommand（）; 并收到以下错误：
无法隐式转换类型'PortableClassLibrary1.MyCommand来 System.Windows.Input.ICommand。一个显式转换存在（是 缺少强制转换？）
由于某种原因，PCL似乎并不键入推进 System.Windows.dll中[2.0.5.0] 的ICommand到 System.dll中[ 4.0.0.0] 的ICommand我的桌面应用程序...唉！
更新3：
我上传我的解决方案，使其以更加醒目什么问题是，
更新4：
我已经开了一个<一个href="https://connect.microsoft.com/VisualStudio/feedback/details/811512/portable-class-library-forces-me-to-add-system-windows-dll-to-my-wpf-project"相对=nofollow>微软连票这个问题。
更新5：
这是心烦这不工作...和其他人告诉我，他们没有得到相同的接口的错误平静下来之后。我认识到，加入 System.Windows.dll中的副作用是一个ReSharper的8.1错误。我想是时候抱怨ReSharper的，而不是微软。 叹息的
您必须添加一个引用程序集System.Windows，版本= 2.0.5.0
的建议是优秀的，该消息并没有很大的。显然，你有莫名其妙的版本号。右键单击您的WPF项目，添加引用，并勾选 System.Windows 。解决了你的问题。
缺少神奇的是这条线在System.Windows.dll中引用程序集：
[总成：TypeForwardedTo（typeof运算（ICommand的））]
它得到了ICommand向前System.Windows.dll中到System.dll中
请记住，System.Windows.dll中从C：\ Program Files文件（x86）的\引用程序集子目录的只是的参考组装。它不包含任何code或类型的所有，只是[TypeForwardedTo]属性。它作为一个调节器，弥合不同的.NET架构平台之间的差距。最终的可执行文件实际上并没有一个依赖于System.Windows.dll中的。
Some background information:
- I am using VS 2013
- I created a Portable Class Library (Targets: .NET 4.5/Silverlight 5/Win Phone 8/Win Store 8)
- I implemented the
ICommandinterface in my class namedMyCommand.
MyCommand.cs:
public class MyCommand : ICommand
{
public bool CanExecute(object parameter)
{
throw new NotImplementedException();
}
public void Execute(object parameter)
{
throw new NotImplementedException();
}
public event EventHandler CanExecuteChanged;
}
I found that when I attempted to reference use the MyCommand class in a WPF 4.5 application, I get the following error:
The type 'System.Windows.Input.ICommand' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Windows, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, Retargetable=Yes'.
I'm not really sure why this is happening, or what I can do to resolve it appropriately. After scouring the internet, I found answers talking about adding a reference to System.Windows.dll 4.0.0.0 in my WPF application. Doing this allows me to compile and run the application, but my IDE complains that:
Interface member 'void System.Windows.Markup.IComponentConnector.Connect(in, object)' is not implemented.
This occurs for my MainWindow.cs class. Is there a better fix than to just deal with this bug so I'm not adding a reference to System.Windows.dll in a WPF application which really doesn't need it? And I say that it doesn't really need it because if I copy/paste the MyCommand class into the Wpf app it works fine. It only has an issue because I am attempting to use it as a portable class library.
UPDATE:
It seems that there is more to this than meets the eye. I created a new Wpf Application and used NuGet to reference the MvvmCross solution (since it has an MvxCommand object). When I do this, I get the same error.
David Kean's answer to a similar question suggests that this should be fixed via VS2012/VS2013 and if not, just reinstall/repair. I fully removed my VS installation and reinstalled it from scratch (VS2013) and still have this issue. So, is this truly a bug or did I do something wrong here?
UPDATE 2:
I attempted to see if I could assign an instance of the MyCommand class to ICommand: ICommand cmd = new MyCommand(); and received the following error:
Cannot implicitly convert type 'PortableClassLibrary1.MyCommand' to 'System.Windows.Input.ICommand'. An explicit conversion exists (are you missing a cast?)
For some reason the PCL does not seem to type forward the System.Windows.dll [2.0.5.0] ICommand to System.dll [4.0.0.0] ICommand for my desktop application... Ugh!
Update 3:
I uploaded my solution so that it is more visible as to what the problem is.
Update 4:
I've opened a Microsoft connect ticket on this issue.
Update 5:
After calming down from being upset about this not working... and others telling me that they don't get the same "interface" error. I realize that the "side-effect" of adding System.Windows.dll was a ReSharper 8.1 error. I guess it's time to complain to ReSharper instead of Microsoft. sigh
You must add a reference to assembly 'System.Windows, Version=2.0.5.0
The advice is excellent, the message is not that great. Clearly you got baffled by the version number. Right-click your WPF project, Add Reference and tick System.Windows. Which solves your problem.
The missing magic is this line in the System.Windows.dll reference assembly:
[assembly: TypeForwardedTo(typeof(ICommand))]
Which gets ICommand forward from System.Windows.dll to System.dll
Keep in mind that System.Windows.dll from the c:\program files (x86)\reference assemblies subdirectory is just a reference assembly. It doesn't contain any code or types at all, just [TypeForwardedTo] attributes. It acts as an "adapter", bridging the gap between different .NET framework platforms. The final executable doesn't actually have a dependency on System.Windows.dll at all.
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