I am trying to implement two interfaces, using the same delegate for both. So if I want to implement these interfaces:

interface A {
    fun foo()
}

interface B {
    fun bar()
}

with a delegate from this class

class C: A, B {
    override fun foo() {
        println("foo!")
    }

    override fun bar() {
        println("bar!")
    }
}

to do it using the by keyword, I could try something like this

class D: A by C(), B by C()

but this requires creating two instances of C, which may not be desirable.

Or I could try

class D(c: C = C()): A by c, B by c

which requires changing the constructor. This may also not be desirable.

Is there some way to do this efficiently, or do I have to go with boilerplate and implement A and B in the class body?