this might be a more generic DI question but tryin...

# kotlin-inject

[Josh Feinberg]

this might be a more generic DI question but trying to find a way to handle this. i have a class that implements two interfaces, InterfaceA and InterfaceB. i have one object that needs a set of InterfaceA implementations and another that needs an implementation of InterfaceB. not sure the best way to handle this (code in 🧵 in case this makes no sense)

[Josh Feinberg]

@Component
abstract class AppComponent {
    
    @IntoSet
    @Provides
    fun provideInterfaceA(): ? {
        return MyObject()
    }
    
    @Provides
    fun provideStuff(interfaceAs: Set<InterfaceA>) {
        
    }
    
    @Provides
    fun provideOtherStuff(interfaceB: InterfaceB) {
        ...
    }
    
}

class MyObject : InterfaceA, InterfaceB {
    ...
}

[Josh Feinberg]

so far the options I can think of are to have 2 provides functions, or have provideOtherStuff accept a Set<InterfaceA> and then just do interfaceAs.filterInstanceOf { InterfaceB } or something

[Josh Feinberg]

i think the ideal solution would be to have IntoSet take a parameter for an object type so I could do

@IntoSet(InterfaceA::class)
@Provides
fun provideInterfaceB(): InterfaceB {
    return MyObject()
}

which would create the set binding for InterfaceA and the provides method for InterfaceB

[Asapha]

This should work:

@Component
abstract class AppComponent {
    // Provide the impl
    @Provides
    fun provideMyObject(): MyObject {
        return MyObject()
    }
    
    // Then bind it to whatever interfaces you need
    @IntoSet
    @Provides
    fun provideInterfaceA(myObject: MyObject): InterfaceA {
        return myObject
    }
    
    @Provides
    fun provideInterfaceB(myObject: MyObject): InterfaceB {
        return myObject
    }
    
    @Provides
    fun provideStuff(interfaceAs: Set<InterfaceA>) {
        
    }
    
    @Provides
    fun provideOtherStuff(interfaceB: InterfaceB) {
        ...
    }   
}

[Josh Feinberg]

that requires me to know that MyObject inherits from both InterfaceA and interfaceB though and hard code that. with your solution, i'm not sure how i'd do a test replacement other than making MyObject inherit from a third interface so that i can inject that so that i can inject a fake for my tests