Kotlin generic class overload?

Question

I want to create some classes with variable number of type argument.

For example, a tuple class:

class Tuple<T1>{
    //blah 
}
class Tuple<T1,T2>{
    //blah blah 
}
class Tuple<T1,T2,T3>{
    //blah blah blah
}

but it shows "redeclaration" error, any suggestion?

Answer 1

You can't do that, because a Kotlin class must have a unique fully qualified name (ie its package name plus the simple name Tuple ).

Depending on what you prefer, you can name those classes following the TupleN pattern ( Tuple1 , Tuple2 etc.) and make a common interface Tuple , and also a set of factory functions sharing the name ( tuple(...) ) with different numbers of parameters for creating tuples of different arities:

fun <T1> tuple(t1: T1) = Tuple1(t1)

fun <T1, T2> tuple(t1: T1, t2: T2) = Tuple2(t1, t2)

fun <T1, T2, T3> tuple(t1: T1, t2: T2, t3: T3) = Tuple3(t1, t2, t3)

/* ... */

Having faced a similar problem, I personally resorted to generating the TupleN classes that I needed.