How do I get type checking on a generic parameter of unrelated interfaces?

[stable vortex]

!pg

[minor oyster]

View in Playground

[rain axle]

You could do something like this:

type AbstractUnrelatedInterface<V extends Discriminator> = InterfaceA | InterfaceB | InterfaceC

interface InterfaceA {
  a: string;
}

interface InterfaceB {
  b: boolean;
}

interface InterfaceC {
  c: number;
}

[stable vortex]

interesting

yeah that works

[stable vortex]

My concern is forgetting to keep externalDiscriminatorTuple and the AbstractUnrelatedInterface in sync. Would that be an easy mistake to make?

I need the former for an unrelated purpose:

declare getNextDiscriminator(d: Discriminator): NextDiscriminator
//   getNextDiscriminator('a') = 'b'
//   getNextDiscriminator('b') = 'c'
//   getNextDiscriminator('c') = never

[rain axle]

Probably not

[stable vortex]

aw I misunderstood. You were saying that was a difficult mistake to make

Well okay, thank you for the help!