class - Limitation with classes derived from generic classes in swift

Question

I'm trying to derive my class from generic class:

class foo<T> {}
class bar : foo<Int> {}

But this code fails to compile with en error:

Classes derived from generic classes must also be generic

How to avoid this limitation? Is it possible?

question from:https://stackoverflow.com/questions/24138359/limitation-with-classes-derived-from-generic-classes-in-swift

Answer 1

Ssreg,

Unfortunately this is official:

You can subclass a generic class, but the subclass must also be a generic class.

Let us hope Apple fixes this in a future version.

Meanwhile, let us see this as an opportunity to exploit aggregation instead of subclassing.

NOTE:

As a poor man's version of a solution, one could use typealias:

class foo<T> {}
class bar<Int> : foo<Int> {}
typealias Bar = bar<Int>

This way, the rest of the code can be written just as if Apple already fixed the matter.