考虑需要创建一些递归嵌套事物的情况，例如：
public interface IRecurrentTestNodeFactory
{
RecurrentTestNode Create(int num);
}
public class RecurrentTestNode
{
public int Num { get; set; }
public RecurrentTestNode Child { get; set; }
public RecurrentTestNode(int num, IRecurrentTestNodeFactory factory)
{
Num = num;
Child = num > 0 ? factory.Create(num - 1) : null;
}
}
明显的实现是这样的：
public class ManualRecurrentTestNodeFactory : IRecurrentTestNodeFactory
{
public RecurrentTestNode Create(int num)
{
return new RecurrentTestNode(num, this);
}
}
[Test]
public void ManualRecurrentTest()
{
var root = new ManualRecurrentTestNodeFactory().Create(1);
Assert.NotNull(root);
Assert.AreEqual(1, root.Num);
Assert.NotNull(root.Child);
Assert.AreEqual(0, root.Child.Num);
Assert.Null(root.Child.Child);
}
该测试通过。但是，如果您尝试对 Windsor 的 Typed Factory Facility 做同样的事情：
[Test]
public void RecurrentTest()
{
var windsor = new WindsorContainer();
windsor.Kernel.AddFacility<TypedFactoryFacility>();
windsor.Register(Component.For<IRecurrentTestNodeFactory>().AsFactory());
windsor.Register(Component.For<RecurrentTestNode>().LifeStyle.Transient);
var f = windsor.Resolve<IRecurrentTestNodeFactory>();
var root = f.Create(1);
Assert.NotNull(root);
Assert.AreEqual(1, root.Num);
Assert.NotNull(root.Child);
Assert.AreEqual(0, root.Child.Num);
Assert.Null(root.Child.Child);
}
它失败了，但有以下例外：
Castle.MicroKernel.ComponentActivator.ComponentActivatorException : ComponentActivator: could not instantiate Tests.RecurrentTestNode
----> System.Reflection.TargetInvocationException : Exception has been thrown by the target of an invocation.
----> Castle.MicroKernel.CircularDependencyException : Dependency cycle has been detected when trying to resolve component 'Tests.RecurrentTestNode'.
The resolution tree that resulted in the cycle is the following:
Component 'Tests.RecurrentTestNode' resolved as dependency of
component 'Tests.RecurrentTestNode' which is the root component being resolved.
很明显，为什么这样的代码在服务的情况下会失败，但对于工厂来说，这似乎是不必要的限制。我想留在工厂变体中，因为我在那里有一堆容器解析的依赖项，而不是普通的 int 。