What about always having the null validator registered, and then overriding it as needed?
2012/1/6 Kenneth Siewers Møller <[email protected]> > Yeah, that was what I was thinking about, but how do I return the null > object, if what I'm looking for isn't registered? > > Kenneth > > > On Fri, Jan 6, 2012 at 01:41, Rory Plaire <[email protected]> wrote: > >> What about using http://en.wikipedia.org/wiki/Null_Object_pattern for a >> null validator? Then you don't need to customize the factory and you also >> don't have to test for null. >> >> -r >> >> 2012/1/5 Kenneth Siewers Møller <[email protected]> >> >>> That's exactly why i wrote in the first place :) >>> >>> I'm not really sure how to approach this then. The point is, that >>> validation is optional. If I should adhere to the open/closed principle, I >>> would think I need only to add a new class to implement the new behavior, >>> correct? >>> >>> So basically, this is what happens: >>> >>> When a new message is created, it is passed to the message validation >>> service. The service has a dependency on a IMessageValidatorFactory (typed). >>> The validation service is calling the factory, passing the message to >>> validate, which in turn is providing a validator for the specific message. >>> If no validator is registered for the message (null), the service should >>> just validate to true. >>> >>> Am I completely off here and is there a better approach? >>> >>> Is there a way to return a default for a service, if none is registered >>> that matches the concrete one, like a DefaultMessageValidator? >>> >>> >>> Kenneth >>> >>> >>> >>> 2012/1/5 Krzysztof Koźmic <[email protected]> >>> >>>> That's not something I would normally recommend but if that's what you >>>> want it should be fine :-) >>>> >>>> K >>>> >>>> >>>> On 05/01/2012 9:51 PM, Kenneth Siewers Møller wrote: >>>> >>>> Hi, >>>> >>>> I'm currently working on an alternative implementation of the >>>> TypedFactoryComponentResolver. >>>> My problem is, that I'd like to use typed factories, but I need to >>>> return null, in case the component isn't registered. >>>> The concrete usecase is, that I'm looking for a validator for a >>>> specific type, and if no validator is registered, it should just return >>>> null from the factory. >>>> As the default implementation always throws an exception, if no >>>> component is registered, I've created my own version. >>>> >>>> /// <summary> >>>> /// Resolves a component. If the component isn't registered, the >>>> resolver returns null instead of an exception. >>>> /// </summary> >>>> internal class NullSafeTypedFactoryComponentResolver : >>>> TypedFactoryComponentResolver >>>> { >>>> public NullSafeTypedFactoryComponentResolver(string componentName, >>>> Type componentType, IDictionary additionalArguments, bool >>>> fallbackToResolveByTypeIfNameNotFound, Type actualSelectorType) >>>> : base(componentName, componentType, additionalArguments, >>>> fallbackToResolveByTypeIfNameNotFound, actualSelectorType) { } >>>> >>>> public override object Resolve(IKernelInternal kernel, IReleasePolicy >>>> scope) >>>> { >>>> // Check to see if the component is registered >>>> var hasComponent = componentName != null >>>> ? kernel.HasComponent(componentName) >>>> : kernel.HasComponent(componentType); >>>> >>>> return hasComponent ? base.Resolve(kernel, scope) : null; >>>> } >>>> } >>>> >>>> I'm then overriding the BuildFactoryComponent method from the >>>> DefaultTypedFactoryComponentSelector, to return my own implementation. >>>> >>>> Since I'm doing something non-standard, I'd just wanted to make sure, >>>> I'm not misusing (or misunderstanding) the concept of a typed factory. >>>> Basically I'm changing the semantics of the container, so I'm just a bit >>>> uncertain about which implications it may bring. >>>> >>>> >>>> Thanks, >>>> Kenneth >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Castle Project Users" group. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msg/castle-project-users/-/GW3SaUL8FTEJ. >>>> To post to this group, send email to >>>> [email protected]. >>>> To unsubscribe from this group, send email to >>>> [email protected]. >>>> For more options, visit this group at >>>> http://groups.google.com/group/castle-project-users?hl=en. >>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Castle Project Users" group. >>>> To post to this group, send email to >>>> [email protected]. >>>> To unsubscribe from this group, send email to >>>> [email protected]. >>>> For more options, visit this group at >>>> http://groups.google.com/group/castle-project-users?hl=en. >>>> >>> >>> >>> >>> -- >>> Med venlig hilsen / Kind regards >>> Kenneth Siewers Møller >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Castle Project Users" group. >>> To post to this group, send email to >>> [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/castle-project-users?hl=en. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Castle Project Users" group. >> To post to this group, send email to >> [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/castle-project-users?hl=en. >> > > > > -- > Med venlig hilsen / Kind regards > Kenneth Siewers Møller > > -- > You received this message because you are subscribed to the Google Groups > "Castle Project Users" group. > To post to this group, send email to [email protected] > . > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/castle-project-users?hl=en. > -- You received this message because you are subscribed to the Google Groups "Castle Project Users" group. 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