我使用的是simpleinjector 2.3.0.0和.net 4.5。
我一直在尝试注册一个依赖于IEnumerable的工厂，一个Thing的实例，以及一个单元工作装饰器。 （除其他外）
这是我的工厂：
public class ThingFactory : IThingFactory
{
private readonly IEnumerable<IThing> things;
public ThingFactory (IEnumerable<IThing> things)
{
this.things= things;
}
public IThing GetThing(ThingType thingType)
{
return things.FirstOrDefault(t => t.IsApplicable(thingType));
}
}
这是我的IThing实现
public class ThingOne: IThing
{
private IThingFactory thingFactory;
public ThingOne(IThingFactory thingFactory)
{
this.thingFactory= thingFactory;
}
public void Execute(MyDto myDto)
{
//do stuff
//get the next approiate IThing out of the factory and execute
}
public bool IsApplicable(ThingType thingType)
{
return thingType == ThingType.ThingOne;
}
}
我的注册是
container.RegisterAll<IThing>(
from tp in typeof (IThing).Assembly.GetExportedTypes()
where !tp.IsAbstract
where typeof (IThing).IsAssignableFrom(tp)
select tp);
container.Register<IThingFactory , ThingFactory>();
这绝对没问题，我可以毫无例外地验证容器。 但是，当我还向容器添加以下注册时，我得到一个异常
container.RegisterDecorator(typeof(ICommandHandler<,>),
typeof(UnitOfWorkDecorator<,>));
装饰器是一个Nhibernate UnitOFWork，它管理一个Nhibernate事务（不重要）（遵循这种模式https://cuttingedge.it/blogs/steven/pivot/entry.php?id=91）
public class UnitOfWorkDecorator<TCommand, TResult>
: ICommandHandler<TCommand, TResult>
where TCommand : ICommand
{
public UnitOfWorkDecorator(
ICommandHandler<TCommand, TResult> decoratedCommandHandler)
{
this.currentSessionContextService = currentSessionContextService;
this.decoratedCommandHandler = decoratedCommandHandler;
}
public void Handle(TCommand command)
{
//start my nhibernate transaction
decoratedCommandHandler.Handle(command);
//commit the transaction
}
所以无论如何，当我添加装饰器时，我得到以下异常。当我打电话
container.Verify();
然而，当我删除装饰者注册时，一切都很好。
Topshelf v3.1.107.0, .NET Framework v4.0.30319.18052
Topshelf.Hosts.ConsoleRunHost Error: 0 : An exception occurred, System.Reflectio
n.TargetInvocationException: Exception has been thrown by the target of an invoc
ation. ---> System.InvalidOperationException: The configuration is invalid. Crea
ting the instance for type IThingManager failed. The registered delegate for t
ype IThingManager threw an exception. The registered delegate for type IThingFa
ctory threw an exception. The registered delegate for type IEnumerable<IThing> th
rew an exception. No registration for type ThingOne could be found a
nd an implicit registration could not be made. ---> SimpleInjector.ActivationEx
ception: The registered delegate for type IThingManager threw an exception. Th
e registered delegate for type IThingFactory threw an exception. The registered d
elegate for type IEnumerable<IThing> threw an exception. No registration for type
ThingOne could be found and an implicit registration could not be m
ade. ---> SimpleInjector.ActivationException: The registered delegate for type
IThingFactory threw an exception. The registered delegate for type IEnumerable<IThing>
threw an exception. No registration for type ThingOne could be
found and an implicit registration could not be made. ---> SimpleInjector.Activ
ationException: The registered delegate for type IEnumerable<IThing> threw an exc
eption. No registration for type ThingOne could be found and an impl
icit registration could not be made. ---> SimpleInjector.ActivationException: N
o registration for type ThingOne could be found and an implicit regi
stration could not be made.
堆栈跟踪：
at SimpleInjector.Container.ThrowNotConstructableException(Type concreteType)
at SimpleInjector.Container.ThrowMissingInstanceProducerException(Type servic
eType)at SimpleInjector.Container.GetRegistration(Type serviceType, Boolean throwOn
Failure) at SimpleInjector.Advanced.ContainerControlledCollection`1.
<>c__DisplayClass1
0.<ToLazyInstanceProducer>b__f() at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue() at
SimpleInjector.Advanced.ContainerControlledCollection`1.<SimpleInjector.Ad
vanced.IContainerControlledCollection.GetRelationships>b__1(Lazy`1 p)
at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
at System.Linq.Enumerable.<SelectManyIterator>d__31`3.MoveNext()
at System.Linq.Enumerable.<DistinctIterator>d__81`1.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at SimpleInjector.Advanced.ContainerControlledCollection`1.SimpleInjector.Adv
anced.IContainerControlledCollection.GetRelationships()
at SimpleInjector.Extensions.Decorators.DecoratorHelpers.ContainerControlledC
ollectionRegistration.GetRelationshipsCore()
at SimpleInjector.Registration.GetRelationships()
at SimpleInjector.InstanceProducer.GetRelationships()
at SimpleInjector.Container.OnExpressionBuilt(ExpressionBuiltEventArgs e, Ins
tanceProducer instanceProducer)
at SimpleInjector.InstanceProducer.BuildExpressionInternal()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at SimpleInjector.InstanceProducer.BuildExpression()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.BuildExpression()
at SimpleInjector.Advanced.DefaultConstructorInjectionBehavior.BuildParameter
Expression(ParameterInfo parameter)
at SimpleInjector.Registration.BuildParameterExpressionFor(ParameterInfo para
meter)
at SimpleInjector.Registration.<BuildNewExpression>b__1a(<>f__AnonymousTypef`
2 <>h__TransparentIdentifier18)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at SimpleInjector.Registration.BuildNewExpression(Type serviceType, Type impl
ementationType)
at SimpleInjector.Registration.BuildTransientExpression[TService,TImplementat
ion]()
at SimpleInjector.Lifestyles.TransientLifestyle.TransientLifestyleRegistratio
n`2.BuildExpression()
at SimpleInjector.InstanceProducer.BuildExpressionInternal()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at SimpleInjector.InstanceProducer.BuildExpression()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.BuildExpression()
at SimpleInjector.Advanced.DefaultConstructorInjectionBehavior.BuildParameter
Expression(ParameterInfo parameter)
at SimpleInjector.Registration.BuildParameterExpressionFor(ParameterInfo para
meter)
at SimpleInjector.Registration.<BuildNewExpression>b__1a(<>f__AnonymousTypef`
2 <>h__TransparentIdentifier18)
at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at SimpleInjector.Registration.BuildNewExpression(Type serviceType, Type impl
ementationType)
at SimpleInjector.Registration.BuildTransientExpression[TService,TImplementat
ion]()
at SimpleInjector.Lifestyles.TransientLifestyle.TransientLifestyleRegistratio
n`2.BuildExpression()
at SimpleInjector.InstanceProducer.BuildExpressionInternal()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at SimpleInjector.InstanceProducer.BuildInstanceCreator(Object& createdInstan
ce)
at SimpleInjector.InstanceProducer.GetInstance()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.GetInstance()
at SimpleInjector.InstanceProducer.Verify()
--- End of inner exception stack trace ---
at SimpleInjector.InstanceProducer.Verify()
at SimpleInjector.Container.VerifyProducers(InstanceProducer[] producersToVer
ify)
at SimpleInjector.Container.ValidateRegistrations()
at SimpleInjector.Container.Verify()
感谢您的帮助
编辑 - ThingManager是入口点，如下所示：
public class ThingManager : IThingManager
{
private readonly IThingFactory thingFactory;
public ThingManager(IThingFactory thingFactory)
{
this.thingFactory = thingFactory;
}
public void Run(MyDto myDto)
{
var firstThing = thingFactory.GetThing(ThingType.ThingOne);
firstThing.Execute(myDto);
}
}
答案 0 :(得分：2)
问题是由代码中的循环引用引起的：ThingFactory取决于IEnumerable<IThing>，这取决于ThingOne，这取决于ThingFactory，这会关闭循环
不幸的是，由于Simple Injector 2.3中的a bug，隐藏了描述循环引用的真正错误，并且抛出了较少表达（在这种情况下甚至是不正确的）消息。此错误已在Simple Injector 2.3.5中修复。
尽管代码库中存在循环引用，但Verify方法仅在注册装饰器时注意到此错误。内部ContainerControlledCollection<T>导致已注册的元素被预编译，允许InstanceProducer实例注意循环。如果没有ContainerControlledCollection<T>，则会更加懒惰地评估集合，这会完全隐藏此错误，即使在解析类型时也是如此。然而，你设计中的这个怪癖可能会在以后引起各种各样的麻烦。
对于即将推出的Simple Injector 2.4，ContainerControlledCollection<T>实际上会更加懒惰，以便在未调用Verify()的情况下提高性能（这对于具有深层对象图和具有许多集合的应用程序有意义items），但这意味着即使使用装饰器，验证者也不会抛出异常。
Simple Injector 2.4不抛出异常的行为实际上是正确的（并且2.3和2.3.5引发异常的事实可以被认为是一个错误），因为Simple Injector的目标是在构建对象时防止stackoverflow异常图表（调用GetInstance时）。由于类型的创建被延迟，因为使用了IEnumerable<T>（解析IEnumerable<T>不解析实例;只迭代集合确实），没有堆栈溢出异常。
虽然在代码中使用循环引用可能是代码味道，但在代码中它可能只会导致代码中的递归（但没有堆栈溢出），这可能是预期的行为。
你仍然可能想重新考虑设计，因为递归深度为10（假设你有10件东西并且叫工厂去接下来的东西），这将触发创造55件事（10倍于第一件） element，9x second element，8x third，... 1x the tennth），这可能不是你所期望的。