Ayende @ Rahien

Ayende Rahien commented on Dependency Injection in a Dynamic Environment

Thu, 23 Aug 2007 19:38:23 GMT

Tudor, > why would you create a Policy which is not valid? BuildPolicy builds a Policy instance from user's input, which is assume to be invalid by default. > I assume that the Repository should persist the whole UnitOfWork No, the repository just handles saving & querying, the UnitOfWork handles the UoW's life cycle. > UnitOfWork.Current, Repository, ValidatorRunner, are some sort of singletons. How did you unit-test the above code? UoW & Repository are static accessors to the container, they are mockable using the Auto Mocking Container. ValidatorRunner is a instance property on the controller. > - I observed that when ValidatorRunner.IsValid(..) returns false, you call ValidatorRunner.GetErrorSummary(...). I would express this as: bool ValidateRunner.Validate(policy, Action set_summary). ValidatorRunner comes from Castle.Component.Validation, and I peronally like this API approach. Yours is equally valid, so I guess it is a matter of taste.

Ayende Rahien commented on Dependency Injection in a Dynamic Environment

Thu, 23 Aug 2007 17:21:30 GMT

I don't like mocking my entities in general, although it is the case that entities may also be domain services. I had a long discussion about this with JP & Udi at DevTeach, and I don't think that taking mocking to the entities is necessary in most cases.

hammett commented on Dependency Injection in a Dynamic Environment

Thu, 23 Aug 2007 15:16:23 GMT

> you still need some sort of dependencies management, if only to provide a way to handle this as applications grow. Absolutely. I had ventured on that field myself, as I was disgusted with objects creating and configuring others. Ruby has Needle, Python has, well a lot of tools.

Tudor-Andrei Pamula commented on Dependency Injection in a Dynamic Environment

Thu, 23 Aug 2007 13:11:46 GMT

if the code is there for my "critique" ;) - why would you create a Policy which is not valid? - I assume that the Repository should persist the whole UnitOfWork (all/or nothing). In that case I would say that the Repository should flush the UnitOfWork. (or probably I misunderstood something) - I assume that UnitOfWork.Current, Repository, ValidatorRunner, are some sort of singletons (static instantiations) How did you unit-test the above code? From my experience, it is very hard to substitute such globals, usually I had to Singleton.ReplaceInstanceWithAnotherInstanceOnlyInTests(x), or to use a strange inheritance tree... - I observed that when ValidatorRunner.IsValid(..) returns false, you call ValidatorRunner.GetErrorSummary(...). I would express this as: bool ValidateRunner.Validate(policy, Action set_summary). With this, and given Scope has a method Scope.SetErrorSummary(string) I would call: if (! ValidatorRunner.Validate(policy, Scope.SetErrorSummary)) return false; - I would write the code like this: public virtual bool AddNewPolicy() { using (RhinoTransaction transaction = UnitOfWork.Current.BeginTransaction()) { Policy policy = BuildPolicy(); if (! ValidatorRunner.Validate(policy, Scope.SetErrorSummary)) { return false; } if (! ValidateThatUserIsAuthorizedToSavePolicy(policy)) { return false; } bool valid_policy_added = AddValidPolicy(policy); if (valid_policy_added) { transaction.Commit(); SetupRedirect(Policy); } return valid_policy_added; } } regards, tap.

Colin Jack commented on Dependency Injection in a Dynamic Environment

Thu, 23 Aug 2007 09:17:56 GMT

Superb post and yeah I think you are dead right, you have to be clear which layer you are working on in terms of DI. I also agree that DI into the domain is a bad idea, as you say the domain classes should be able to stand on their own. Now here is a question I have. Lets say I have an Application layer service that calls to a repository, then to an infrastructure service, then into a domain service/entity and then returns. In that case I can inject in the repository and infrastructure service to do interaction testing of the Application layer service, but would you also inject the domain service/entity? There are very varying opinions on this but I'm interested to hear which way you approach this.