If i do inheritance by delegation, is it possible ...

# announcements

[Teknight]

If i do inheritance by delegation, is it possible to interact with the parent, from within the delegated class?
Say we have:
class MyClass: IDelegate by MyDelegatedClass()
Can i access the MyClass instance from within MyDelegatedClass in any way?

[hudsonb]

I believe to do that you have to do something like

class MyClass(val delegate: MyDelegatedClass = MyDelegatedClass()) : IDelegate by delegate

Then you can access it via delegate if you'd like

[hudsonb]

Sorry re-read your question, I had this backwards

[Teknight]

Hi thank you,
This way i can access the delegated class instance from MyClass, then i could pass "this" to the delegated instance, but would prefer not to do this

[Alowaniak]

I think @Teknight wants the other way around?

[Alowaniak]

basically you want something like class MyClass: IDelegate by MyDelegatedClass(this) right?

[hudsonb]

MyDelegatedClass has no no knowledge of MyClass unless you provide it via something like class MyClass: IDelegate by MyDelegatedClass(this)

[Alowaniak]

but I don't think that this is valid there yet

[Teknight]

Yes, exactly, however i cannot pass this there

[Alowaniak]

so I guess you would have to go the val delegate and then set it in init route?

[hudsonb]

Ya

[Teknight]

No my problem exactly. I made a function to pass this in init, but I would like to not have to do this, since i will create a lot of classes with this delegate

[Teknight]

So a lot of classes will have this "attachObject" logic

[Teknight]

Oh well, if that is the only solution, then i will keep that.
Was hoping there would maybe be some reflection i could use, to get which instance was delegating the MyDelegatedClass instance.

[Teknight]

Thank you both 🙂

[Alowaniak]

Maybe you can change it so the MyDelegatedClass doesn't need the this but only a part of it and you can extract that so you get

interface A
class MyA(private val b: PartialB) : A
class FullB(private val partialB: PartialB = PartialB()) : A by MyA(partialB)
class PartialB

And quite possibly maybe there are even better solutions

[Dico]

https://github.com/Kotlin/KEEP/issues/155
Upvotes and/or feedback appreciated