Hello everyone. I want to share in an internal library a repository that I use in several projects. ...

# getting-started

[Francis Mariano]

Hello everyone. I want to share in an internal library a repository that I use in several projects. But I am with trouble with generics. More details in the thread.

[Francis Mariano]

interface HardwareType<T>

interface PeripheralType<T> {
    val peripheral: Peripheral
    val type: HardwareType<T>
}

interface PeripheralRepository<T> {
    val peripherals: StateFlow<Map<String, PeripheralType<T>>>
}

object PeripheralRepositoryImpl : PeripheralRepository <T> {
    override val peripherals: StateFlow<Map<String, PeripheralType<T>>>
        get() = TODO("Not yet implemented")
}

The repository is a object and one object can not has generics type. The HardwareType depends on client is consuming the library.

[Francis Mariano]

There are other approach can I use???

[Joffrey]

Why not just make the implementation a generic class instead of an object?

[Francis Mariano]

Because in first moment the repository is a singleton in my several projects. Implementing a generic class I will have to use a framework of injection or creating the repository in high level of the application and distributing to all the classes that use it.

I think the second approach is coherent.

[Joffrey]

Mmh you could always do this in the consumers:

val mySpecificRepo by lazy { PeripheralRepositoryImpl<SpecificT>() }

[Francis Mariano]

so using by lazy in the consumers (different classes) I get the same reference of object? I did not know about that.

[Francis Mariano]

I was wrong. by lazy do not guarantee the same reference of object

[Joffrey]

What do you mean? Lazy is synchronized by default and will compute the value the first time, and then reuse the same for every subsequent calls

[Francis Mariano]

https://play.kotlinlang.org/#eyJ2ZXJzaW9uIjoiMi4wLjAiLCJwbGF0Zm9ybSI6ImphdmEiLCJhcmdzIj[…]B2YWwgZm9vID0gRm9vKClcbiAgICB2YWwgYmFyID0gQmFyKClcbn0ifQ==

In the code above Repository is initialized for 3 times and is different instance for Foo and Bar

[Joffrey]

But you have created 3 different properties here, so yes. Why not create just one property? I am assuming you were using an object before, that you declared once and used in different places. Similarly, you could declare a top-level property initialized lazily once, and use it everywhere

[Joffrey]

https://pl.kotl.in/4zoxEEE2K

[Francis Mariano]

ahhh ok, I did not think in this way. works too.

[Francis Mariano]

thank you