Discriminated Types
TypeSpec allows for the expression of unions and inheritance. However, when transmitting types over the network, many languages require a mechanism to distinguish between different union variants or models within an inheritance hierarchy.
To facilitate this, TypeSpec offers the @discriminator
decorator.
Implementing Polymorphism
string
Discriminator
@discriminator("kind")
model Pet {
name: string;
weight?: float32;
}
model Cat extends Pet {
kind: "cat";
meow: int32;
}
model Dog extends Pet {
kind: "dog";
bark: string;
}
enum
Discriminator
enum PetKind {
cat,
dog,
}
@discriminator("kind")
model Pet {
kind: PetKind;
name: string;
weight?: float32;
}
model Cat extends Pet {
kind: PetKind.cat;
meow: int32;
}
model Dog extends Pet {
kind: PetKind.dog;
bark: string;
}
Nested Discriminator
@discriminator("kind")
model Pet {
kind: string;
name: string;
weight?: float32;
}
@discriminator("breed")
model Cat extends Pet {
kind: "cat";
breed: string;
meow: int32;
}
@discriminator("breed")
model Siamese extends Cat {
breed: "siamese";
}
@discriminator("breed")
model Bengal extends Cat {
breed: "bengal";
}
model Dog extends Pet {
kind: "dog";
bark: string;
}
Implementing Unions
@discriminator("kind")
union Pet {
cat: Cat,
dog: Dog,
}
model Cat {
kind: "cat";
meow: int32;
}
model Dog {
kind: "dog";
bark: string;
}