Kodein is a very simple and yet very useful dependency retrieval container. it is very easy to use and configure.
Kodein allows you to:
- Lazily instantiate your dependencies when needed
- Stop caring about dependency initialization order
- Easily bind classes or interfaces to their instance or provider
- Easily debug your dependency bindings and recursions
Kodein does not allow you to:
- Automatically instantiate your dependencies via injected constructor and reflexivity. For that, you need Guice.
- Have dependency injection validated at compile time. For that, you need Dagger.
Kodein is a good choice because:
- It is small, fast and optimized (makes extensive use of
inline) - It proposes a very simple and readable declarative DSL
- It is not subject to type erasure (like Java)
- It integrates nicely with Android
- It proposes a very kotlin-esque idiomatic API
- It can be used in plain Java
An example is always better than a thousand words:
val kodein = Kodein {
bind<Dice>() with provider { RandomDice(0, 5) }
bind<DataSource>() with singleton { SqliteDS.open("path/to/file") }
}
class Controller(private kodein: Kodein) {
private val ds: DataSource = kodein.instance()
}Kodein version 3 is the current major version available:
If you are currently using a javax.inject compatible dependency injection library and whish to migrate to Kodein, there is a guide for that.
Well, I'd like to know!
If you are using Kodein, please let me know by mail.
A public list will be displayed here soon :)