解决 Ninject（紧凑框架）中的循环依赖

Question

我正在尝试在我的 MVP 应用程序中使用 Ninject 进行依赖项注入。但是，我有一个问题，因为我有两种相互依赖的类型，从而创建了循环依赖。起初，我知道这是一个问题，因为我的两种类型在其构造函数中都需要彼此。因此，我将其中一个依赖项移至属性注入，但仍然收到错误消息。我做错了什么？

这是演示者：

public class LoginPresenter : Presenter<ILoginView>, ILoginPresenter
{
    private ISettings _settings;
    private IViewProvider _viewProvider;
    private IDataProvider _dataProvider;

    public LoginPresenter(
        ILoginView view,
        ISettings settings,
        IViewProvider viewProvider,
        IDataProvider dataProvider )
        : base( view )
    {
        _settings = settings;
        _viewProvider = viewProvider;
        _dataProvider = dataProvider;
    }
}

这是视图：

public partial class LoginForm : Form, ILoginView
{
    [Inject]
    public ILoginPresenter Presenter { private get; set; }

    public LoginForm()
    {
        InitializeComponent();
    }
}

这是导致异常的代码：

static class Program
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [MTAThread]
    static void Main()
    {
        // Show the login form
        Views.LoginForm loginForm = Kernel.Get<Views.Interfaces.ILoginView>() as Views.LoginForm;
        Application.Run( loginForm );
    }
}

异常发生在调用 Kernel.Get<>() 的行上。就是这样：

Error activating ILoginPresenter using binding from ILoginPresenter to LoginPresenter
A cyclical dependency was detected between the constructors of two services.

Activation path:
  4) Injection of dependency ILoginPresenter into property Presenter of type LoginForm
  3) Injection of dependency ILoginView into parameter view of constructor of type LoginPresenter
  2) Injection of dependency ILoginPresenter into property Presenter of type LoginForm
  1) Request for ILoginView

Suggestions:
  1) Ensure that you have not declared a dependency for ILoginPresenter on any implementations of the service.
  2) Consider combining the services into a single one to remove the cycle.
  3) Use property injection instead of constructor injection, and implement IInitializable
     if you need initialization logic to be run after property values have been injected.

为什么 Ninject 不明白，既然一个是构造函数注入，另一个是属性注入，那么这可以正常工作？我什至在某个地方读到寻找这个问题的解决方案，只要循环依赖不同时存在于构造函数中，Ninject 就可以解决这个问题。但显然不是。任何解决此问题的帮助将不胜感激。

根据维基百科，视图手动实例化其具体演示者是很常见的，但在我的例子中我不能这样做，因为如您所见，演示者还有其他依赖项也需要解决。

Answer 1

我通过创建“PresenterProvider”来“解决”这个问题：

public interface IPresenterProvider
{
    P Get<P, V>( V view )
        where V : IView
        where P : IPresenter<V>;
}

public class PresenterProvider : IPresenterProvider
{
    private IKernel _kernel;

    public PresenterProvider( IKernel kernel )
    {
        _kernel = kernel;
    }

    #region IPresenterProvider Members

    public P Get<P, V>( V view )
        where P : IPresenter<V>
        where V : IView
    {
        return _kernel.Get<P>( new ConstructorArgument( "view", view ) );
    }

    #endregion
}

然后，在视图中我这样做：

public partial class LoginForm : Form, ILoginView
{
    private ILoginPresenter _presenter;

    public LoginForm( IPresenterProvider presenterProvider )
    {
        InitializeComponent();
        _presenter = presenterProvider.Get<ILoginPresenter, ILoginView>( this );
    }
}

演示者保持不变。这样，我就可以手动“解决”循环依赖关系。当然，更好的建议仍然受到欢迎。