Hi Jaime, On 12/3/07 4:29 PM, "Jaime Metcher" <[EMAIL PROTECTED]> wrote:
> "A DAO is just a strategy for storing and accessing a large collection, in > the same vein as e.g. using a struct and accessing it via a key, or using an > array and accessing it via a for loop. As such it is an implementation > detail that most certainly belongs within domain objects. I'm not sure that I agree with that completely. I happen to compose my DAOs within my business objects (so I'm arguing against myself here!), but I wouldn't say it is wrong for this to be handled by a service layer - especially when you consider remote object calls and the inability to send rich objects over the wire. I personally solve that by my UserService.save() instantiating a new() user and then User.save()ing, but I don't think there's anything wrong with the service layer approach. > One of the most natural ways to factor this functionality is via the use of > singletons. The fact that it is difficult to inject singletons into domain > objects is a design "accident" that has greatly distorted the design of the > domain model layer. If we could specify DI rules for transient objects and > be confident they would be applied no matter how the object was > instantiated, there would be no anemic domain models." I think you're going to get anemic domain models for as long as developers are having problems "getting" OO and for as long as you have anemic domains (some web apps are fundamentally anemic). However, there is nothing difficult at all about injecting into transients. ColdSpring has a Singleton="false" method, and I wrote LightWire specifically to handle the fact that people I respected suggested that while ColdSpring was capable of injecting into transients it wasn't really planned for that kind of use (I'm not saying you shouldn't use CS for DI into transients - just repeating what I was told at the time). I use LightWire and inject into ALL of my transients (they all have a metadata bean, a validation bean and a DAO) and it's been working great for me for over a year now on a wide range of projects. > During the life of this thread a truly voodoo AOP solution was developed > that intercepts the constructor and calls Spring to instantiate the > transient, with full DI. Sadly, I don't think this would fly in Cold > Fusion - but maybe one of the gurus out there will be inspired to prove me > wrong. Firstly try ColdSpring with singleton=false, and if you have any problems at all, there is always LightWire. It was designed for just this use case of injecting into all your transients and it takes such a lightweight approach to DI I've seen no performance issues at all. At only a few hundred lines of code, it's also a really good way to "get" how simple the concepts behind DI really is if (like me) you're not smart enough to follow all of Chris Scotts' Voodoo that allows ColdSpring to do so much more! Best Wishes, Peter --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "CFCDev" 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/cfcdev?hl=en -~----------~----~----~----~------~----~------~--~---
