kotlinlang #kodein

I’m still figuring out how to create proper dependencies that are scoped on an Activity (or Context). There are quite a few moving parts. What, in your opinion, would be the best or most idiomatic way to do this, to provide dependencies for components that do not necessarily need a Context (they only need one for their creation)?

salomonbrys

03/09/2018, 3:21 PM

Well, do the components are different if the context is different ?

streetsofboston

03/09/2018, 3:23 PM

Yep. As an example, I’m looking at creating

ViewModel

in Android given an

Activity

. The code to create one is

ViewModelProviders.of(thisActivity).get(MyViewModel::class.java)

, which I want to put into a binding.

salomonbrys

03/09/2018, 3:24 PM

OK, so the binding itself do not change

streetsofboston

03/09/2018, 3:24 PM

No, they are fixed per Activity (Context), once created (singleton per Activity)

streetsofboston

03/09/2018, 3:25 PM

(I want to put them into a Kodein binding, so that i can provide different binding when creating unit-tests)

salomonbrys

03/09/2018, 3:33 PM

So, I believe you have to choices: 1. Use a multiton:

bind<ViewModel>() with multiton(ref = weakReference) { activity: Activity -> ViewModelProviders.of(activity).get(MyViewModel::class.java) }

, and retrieve with

val view: MyViewModel by instance<ViewModel>(arg = this) as MyViewModel

. 2. Use a context singleton :

bind<ViewModel>() with singleton(scope = androidScope<Activity>()) { ViewModelProviders.of(context).get(MyViewModel::class.java }

and, in the retriever, set the context:

override val kodeinContext = kcontext(this)

, and finally retrieve it with

val view: MyViewModel by instance<ViewModel>() as MyViewModel

Note that, as you can see, Kodein is not meant to be a sub-class factory. That's a popular demand, so I might look into that.

streetsofboston

03/09/2018, 3:34 PM

Thank you! I’ll look into these two solutions. I don’t need a sub-class factory for this, but yeah, such a factory would be nice 🙂

hamutarto

03/11/2018, 1:23 PM

hey hey! I'm using the 4.1.0 version and I found a strange behavior. I created two new modules (I had 2 before, they worked perfectly fine) but I started to get Binding bind<Object>() with ? { ? } must not override an existing binding. issue

hamutarto

03/11/2018, 5:27 PM

that stuff is tricky 😕

hamutarto

03/11/2018, 5:27 PM

can’t find anything

hamutarto

03/11/2018, 5:27 PM

that is broken

leosan

03/13/2018, 12:36 PM

Hey I’m new to kodein someone could help me I want to provide a

String

tag for a job and the instance of the job but not sure if this is a factory, a provider… what would be similar to this using Kodein

Copy code

@Singleton
class AppJobCreator
    @Inject constructor(
            private val jobs: @JvmSuppressWildcards Map<String, Provider<Job>>
    ): JobCreator {

    override fun create(tag: String): Job? {
        val jobProvider = jobs[tag]
        return jobProvider?.get()
    }
}

leosan

03/13/2018, 2:17 PM

I meant, a module like that

Copy code

@Provides @IntoMap
    @StringKey( SendBookRequestJob.JOB_TAG )
    Job provideSendBookRequestJob (BookApi api, Bus bus)
    {
        return new SendBookRequestJob( api, bus );
    }

streetsofboston

03/14/2018, 6:23 PM

Question about the `closestKodein(Context)`: Could the kodein ‘returned’ by this function cause a leak of the provided

Context

? E.g if I provide the returned Kodein/KodeinAware when creating a class instance that will live longer than that Context (eg a ViewModel lives longer than an Activity)

salomonbrys

03/16/2018, 3:10 PM

@streetsofboston No, it cannot. The provided

Context

is not retained by the returned Kodein object. It is only used to "walk up the context tree" to find the "closest" Kodein, or return the Application Kodein if it does not find one.

streetsofboston

03/16/2018, 3:18 PM

Cool! I like this! I actually just confirmed it last night. I created dependencies using

closestKodein

in various places and started rotating my Activity a bunch of times. Using the memory-monitor, I saw there was only one instance of my Activity after all that --> no leaks 🙂

apatrida

03/31/2018, 4:33 AM

@salomonbrys your docs for 5.0.0 reference a dependency for the generic version that does not exist: https://jcenter.bintray.com/org/kodein/di/ does not contain

kodein-di-generic-jvm

apatrida

03/31/2018, 4:44 AM

I think maybe some methods changed to upper case for first letter too? docs don't match

apatrida

03/31/2018, 4:49 AM

or maybe it is because the dependency isn't there and I just have core? something is wrong...

apatrida

04/01/2018, 1:21 AM

We can't use delegates in default constructor parameters.

anstaendig

04/04/2018, 10:17 AM

Hey there. I wanted to give Kodein a try but fail to import it into the project

anstaendig

04/04/2018, 10:17 AM

Failed to resolve: org.kodein.di:kodein-di-generic-jvm:5.0.0

Joe

04/04/2018, 3:06 PM

Has 5.0 been officially released? Did I miss the announcement somehow? 😮

gaetan

04/05/2018, 12:26 PM

@salomonbrys you should update https://kotlin.link/. It has the link on the previous version.