In Kodein, I have modules imported into a parent module, and sometimes the classes need an instance of Kodein so they can do injection themselves later. The problem is this code:
val parentModule = Kodein {
import(SomeService.module)
}
Where SomeService.module
needs the Kodein instance for later, but Kodein isn't yet created. Passing it later into the module seems like a bad idea.
In Kodein 3.x
I see there is the kodein-conf
module that has a global instance, but I want to avoid the global.
How do other modules or classes get the Kodein instance?
Note: this question is intentionally written and answered by the author (Self-Answered Questions), so that the idiomatic answers to commonly asked Kotlin/Kodein topics are present in SO.
In Kodein 3.x
(and maybe older versions) you have access to a property within the initialization of any module called kodein
that you can use in your bindings.
Within your module, the binding would look like:
bind<SomeService>() with singleton { SomeService(kodein) }
For a complete example and using a separation of interfaces vs. implementation, it might look something like this:
interface SomeService {
// ...
}
class DefaultSomeService(val kodein: Kodein): SomeService {
companion object {
val module = Kodein.Module {
bind<SomeService>() with singleton { DefaultSomeService(kodein) }
}
}
val mapper: ObjectMapper = kodein.instance()
// ...
}
You can import the module from the parent as you noted and it will receive its own reference to the current Kodein instance.
val kodein = Kodein {
import(DefaultSomeService.module)
}