[eiffel31]

> class A(b: B) : B by b // IS_A via composition

I couldn't find the "B by b" syntax from the Kotlin docs, can you tell me that this does ?

[hota_mazi]

It's delegation.

Look at page 96 of this PDF file: https://kotlinlang.org/docs/kotlin-docs.pdf

[eiffel31]

Thank you, wish Java had this :'(