Passing Parameters - Injected Parameters
In any definition, you can use injection parameters: parameters that will be injected and used by your definition.
Passing values to inject
Given a definition, you can pass parameters to that definition:
class Presenter(val a : A, val b : B)
val myModule = module {
single { params -> Presenter(a = params.get(), b = params.get()) }
}
Parameters are sent to your definition with the parametersOf()
function (each value separated by comma):
class MyComponent : View, KoinComponent {
val a : A ...
val b : B ...
// inject this as View value
val presenter : Presenter by inject { parametersOf(a, b) }
}
Defining an "injected parameter"
Below is an example of injection parameters. We established that we need a view
parameter to build of Presenter
class. We use the params
function argument to help retrieve our injected parameters:
class Presenter(val view : View)
val myModule = module {
single { params -> Presenter(view = params.get()) }
}
You can also write your injected parameters directly with the parameters object, as destructured declaration:
class Presenter(val view : View)
val myModule = module {
single { (view : View) -> Presenter(view) }
}
Even if the "destructured" declaration is more convenient and readable, it's not type safe. Kotlin won't detect that passed type are in good orders if you have several values
Resolving injected parameters
Koin graph resolution (main tree of resolution of all definitions) also let you find your injected parameter. Just use the usual get()
function:
class Presenter(val view : View)
val myModule = module {
single { Presenter(get()) }
}