Sorry I couldn't get back sooner, been swamped all week. Okay here is what
i mean. I've attached the full CS file so you can verify
But here is the breakdown for reference
Here are the subjects and their dependencies:
public interface IA
{
IB B {get;}
}
public class A : IA
{
public IB B {get; private set; }
public A(IB b) { B = b; }
}
public interface IB
{
IEnumerable<IC> Cs { get; }
}
public class B : IB
{
public IEnumerable<IC> Cs {get; private set; }
public B(IEnumerable<IC> cs) { Cs = cs; }
}
public interface IC{}
public class C1 : IC
{
public C1() {}
}
public class C2 : IC
{
public IA A { get; private set; }
public C2(IA a) { A = a; }
}
Clearly C2 has a circular dependency but C1 does not.
Here is the test that represents the behaviour that I would like to see
[Test]
public void CastleCircularTest()
{
var container = new WindsorContainer();
container.AddFacility<TypedFactoryFacility>();
container.Kernel.Resolver.AddSubResolver(new
CollectionResolver(container.Kernel, true));
container.Register(AllTypes.FromThisAssembly().Pick().WithServiceAllInterfaces().WithServiceBase());
var resolvedA = container.Resolve<IA>();
Assert.That(resolvedA, Is.Not.Null);
Assert.That(resolvedA.B.Cs.Count(), Is.EqualTo(1));
Assert.That(resolvedA.B.Cs.Single().GetType(),
Is.EqualTo(typeof(C1)));
}
The test (obviously) does not pass. When trying to Resolv IA, I get the
following exception (to recreate this behaviuor, just flip the commented
out lines:
Dependency cycle has been detected when trying to resolve component
'CastleCoreTests.CastleCircularTestFixture+A'.
The resolution tree that resulted in the cycle is the following:
Component 'CastleCoreTests.CastleCircularTestFixture+A' resolved as
dependency of
component 'CastleCoreTests.CastleCircularTestFixture+C2' resolved as
dependency of
component 'CastleCoreTests.CastleCircularTestFixture+B' resolved as
dependency of
component 'CastleCoreTests.CastleCircularTestFixture+A' which is the root
component being resolved.
Okay, so to solve this, I introduce a CustomCollectionResolver, and
register it on the container instead of the CollectionResolver
Registration:
container.Kernel.Resolver.AddSubResolver(new
CustomCollectionResolver(container.Kernel));
The Resolver:
public class CustomCollectionResolver : CollectionResolver
{
private readonly IKernel _kernel;
public CustomCollectionResolver(IKernel kernel)
: base(kernel, true) { _kernel = kernel; }
public override object
Resolve(Castle.MicroKernel.Context.CreationContext context,
ISubDependencyResolver contextHandlerResolver, Castle.Core.ComponentModel
model, Castle.Core.DependencyModel dependency)
{
var resolved = new List<object>();
var handlers =
_kernel.GetHandlers(GetItemType(dependency.TargetItemType));
foreach (var handler in handlers)
{
try
{
resolved.Add(handler.Resolve(context));
}
catch (CircularDependencyException)
{
//Ignore circular dependencies
}
}
return resolved;
}
}
This just leads to {"ComponentActivator: could not instantiate
CastleCoreTests.CastleCircularTestFixture+B"}
{"Object of type 'System.Collections.Generic.List`1[System.Object]' cannot
be converted to type
'System.Collections.Generic.IEnumerable`1[CastleCoreTests.CastleCircularTestFixture+IC]'."}
On Thursday, 18 April 2013 17:17:09 UTC-7, Krzysztof Koźmic wrote:
>
> Nik,
>
> actually I think this should be working out of the box.
>
> Can you please build a simple test reproducing the behavior...
>
> I think I may be missing something here
>
>
> On 18 April 2013 16:15, Nik Pinski <npi...@gmail.com <javascript:>> wrote:
>
>> Creating a custom Collection Resolver sounds promising.
>>
>> So I see that the existing logic for detecting cycles is in
>> DefaultHandler. IsBeingResolvedInContext uses the CreationContext to find
>> out context.IsInResolutionContext(this); which tells it if the handler is
>> already being resolved in the context.
>>
>> Makes sense. But in the context of a SubDependencyResolver that I would
>> be writing (or overriding CollectionResolver), how do i get at the handler?
>> I think I don't understand enough about what step in the resolution
>> lifecycle the subdependencyresolver is invoked...
>>
>>
>> On Wednesday, 17 April 2013 22:21:51 UTC-7, Krzysztof Koźmic wrote:
>>
>>> so I think what you want is a custom Collection resolver that checks
>>> if a IHandler is already in the graph and then ignores it. There's a method
>>> on ResolutionContext or similar that does that
>>>
>>>
>>> HTH
>>> --
>>> Krzysztof Kozmic
>>>
>>> On Wednesday, 17 April 2013 at 3:26 PM, Nik Pinski wrote:
>>>
>>> I have a generic repository (the generic type parameter being the
>>> aggregate root type being serialized to the database [mongo]).
>>>
>>> The repository takes a parameter which in an IEnumerable of ISync
>>> services. Low-level database actions may need to be synchronized to other
>>> data, and implementors of ISync will do that.
>>>
>>> Some psudeocode:
>>>
>>> class Repository<T>
>>> {
>>> public Repository(IEnumerable<ISync<**T>> synchronizers)
>>> {
>>> ...
>>> }
>>>
>>> public void Save(T data)
>>> {
>>> database.Save(data);
>>> foreach(synchronizer in _syncrhonizers)
>>> {
>>> synchronizer.Sync(data);
>>> }
>>> }
>>> }
>>>
>>> class SomeRandomSync : ISync<ObjectA>
>>> {
>>> public void Sync(ObjectAdata)
>>> {
>>> //do something with that object perhaps even use another
>>> repository
>>> new Repository<ObjectB>().Save(**objectB); //Obviously this is
>>> a constructor injection, I'm just keeping it simple
>>> }
>>> }
>>>
>>> Most objects don't have an ISync<T> implementation, so the synchronizers
>>> do nothing.
>>>
>>> However whenever dealing with such low level injected dependencies there
>>> can easily be a dependency cyle. What if there is an implementation of
>>> ISync<ObjectB> that, when syncing ObjectBdecides to Save ObjectA? Well, an
>>> infinite loop of saves and re-saves that LUCKILY, Castle Windsor would
>>> identify ahead of time and tell you "Hey, you've got a dependency cycle and
>>> you're doing something wrong."
>>>
>>> Luckily only 99% of the time, though, because in my case i don't WANT it
>>> to cause a cyclical dependency, I just want that particular ISync<T>
>>> service to be ignored. I want to allow the developers using this code to
>>> be able to create those dependency cycles (sometimes they are quite
>>> necessary because SOME implementors of ISync need to be called, and some
>>> should just be ignored if they can't be - they will surely not cause a
>>> cycle in another situation.
>>>
>>> I tried to do something like this but to no avail
>>> (StackOverflowException). Do I have any recourse?
>>>
>>> public Repository(IWindsorContainer windsorContainer)
>>> {
>>> var handlers = windsorContainer.Kernel.**
>>> GetHandlers(typeof(ISync<T>));
>>>
>>> var syncers = new List<object>();
>>> foreach (var handler in handlers)
>>> {
>>> try
>>> {
>>> object syncer= handler.TryResolve(**
>>> CreationContext.CreateEmpty())**;
>>> syncers.Add(syncer);
>>> }
>>> catch
>>> {
>>> }
>>> }
>>>
>>> _syncers = syncers;
>>> }
>>>
>>> --
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>>> .
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>>>
>>>
>>>
>>>
>>> --
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>
>
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?using System.Collections.Generic;
using Castle.Facilities.TypedFactory;
using Castle.MicroKernel;
using Castle.MicroKernel.Registration;
using Castle.MicroKernel.Resolvers.SpecializedResolvers;
using Castle.Windsor;
using NUnit.Framework;
using System.Linq;
namespace CastleCoreTests
{
[TestFixture]
public class CastleCircularTestFixture
{
public interface IA
{
IB B {get;}
}
public class A : IA
{
public IB B {get; private set; }
public A(IB b) { B = b; }
}
public interface IB
{
IEnumerable<IC> Cs { get; }
}
public class B : IB
{
public IEnumerable<IC> Cs {get; private set; }
public B(IEnumerable<IC> cs) { Cs = cs; }
}
public interface IC{}
public class C1 : IC
{
public C1() {}
}
public class C2 : IC
{
public IA A { get; private set; }
public C2(IA a) { A = a; }
}
[Test]
public void CastleCircularTest()
{
var container = new WindsorContainer();
container.AddFacility<TypedFactoryFacility>();
//The two sub-resolvers
// container.Kernel.Resolver.AddSubResolver(new CollectionResolver(container.Kernel, true));
container.Kernel.Resolver.AddSubResolver(new CustomCollectionResolver(container.Kernel));
container.Register(AllTypes.FromThisAssembly().Pick().WithServiceAllInterfaces().WithServiceBase());
var resolvedA = container.Resolve<IA>();
Assert.That(resolvedA, Is.Not.Null);
Assert.That(resolvedA.B.Cs.Count(), Is.EqualTo(1));
Assert.That(resolvedA.B.Cs.Single().GetType(), Is.EqualTo(typeof(C1)));
}
}
public class CustomCollectionResolver : CollectionResolver
{
private readonly IKernel _kernel;
public CustomCollectionResolver(IKernel kernel)
: base(kernel, true) { _kernel = kernel; }
public override object Resolve(Castle.MicroKernel.Context.CreationContext context, ISubDependencyResolver contextHandlerResolver, Castle.Core.ComponentModel model, Castle.Core.DependencyModel dependency)
{
var resolved = new List<object>();
var handlers = _kernel.GetHandlers(GetItemType(dependency.TargetItemType));
foreach (var handler in handlers)
{
try
{
resolved.Add(handler.Resolve(context));
}
catch (CircularDependencyException)
{
//Ignore circular dependencies
}
}
return resolved;
}
}
}
