``` class Bar<T> protected constructor(type:...

# announcements

[christopher]

class Bar<T> protected constructor(type: Class<T>) {
    companion object {
        inline operator fun <reified T> invoke(): Bar<T> {
            return Bar(T::class.java)
        }
    }
}

val bar = Bar<String>()

[diesieben07]

Not sure I follow how I would use this.

[christopher]

Not sure where the disconnect is. This lets you use Bar<Type>() instead of Bar(Type::class.java). Not what you wanted?

[diesieben07]

Yes, that is what I wanted. However I want this to be a companion object.

[christopher]

it is?

[christopher]

the val bar at the end is just a demonstration.

[diesieben07]

In your case Bar has the class parameter. The companion object should have it.

[christopher]

It does…

[christopher]

Oh, you don’t want the type parameter on the class?

[diesieben07]

Yes.

[christopher]

well, it doesn’t have to be there. but then your parent class won’t know what type of class it’s getting, just that it’s a class

[diesieben07]

data class Person should have a companion object of type Model<Person>, and Model needs the Person class.

[diesieben07]

Model then has methods like findAll, which would return all Person instances.

[christopher]

Type it out as you want it to look, if reified were possible where you want it.

[diesieben07]

class Model<reified T>

[diesieben07]

I know I can emulate that using factory method. However then I can no longer use it as companion object...

[christopher]

oh I see

[diesieben07]

I think delegation using by is the best I can do...

[christopher]

yup, I think so

[christopher]

I’ve been working on an annotation processor to auto generate interfaces for that purpose actually 😆

[diesieben07]

I am trying to move away from annotation processing 🙂 Otherwise I'd being using querydsl or something. But I am trying to be "kotlin idiomatic" in a way 🙂

[christopher]

👍