The AnimalOnDemand app should build as an ordinary Android project.
All that should happen is that the MainActivity should show a screen with the word "Dog" on it
The IoC container should be initialized as soon as possible during app startup: in this case it's done in the custom AnimalOnDemand application class.
For the example I created an extension function for the container (in Ioc.kt) that registers the types
used in the sample:
fun Container.build(): Container {
this.register<INetwork, NetworkHandler>()
this.register<IAnalytics, AnalyticsHandler>()
this.register<IMainViewModel, MainViewModel>()
return this
}Types.kt contains the interfaces used in the examples and the concrete classes are in the handlers and
viewmodels packages.
All activity classes should inherit from a BaseActivity class which fetches a reference to the
singleton container created in the application class.
within the activity, the implementations can be fetched as follows:
lateinit var analytics: IAnalytics
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
analytics = container.resolve()
}The only methods exposed by the library to consumer applications are register<type, implementation>()
and resolve<type>().
I've separated out the Registry and Creator functionality into separate classes as a step towards making them more extensible.
The tests try to cover all the error conditions I could think of and hopefully are fairly comprehensive.
I've not written anything like this before so it's been an interesting exercise. Looking at the code there are a number of areas I can immediately see where the library could be improved:
- There is no concept of Scoping: at least providing support for a Singleton scope would be good.
- Improved validation. It should be possible to add a
checkGraph()function that could be called after all the types have been registered that would create the dependency graph and check it for cyclic dependencies and also to ensure that all the required dependencies were present.