In TypeScript, is there a way for a class to refer to its constructor in a way that works when it is subclassed?
abstract class Base<T> {
constructor(readonly value: T) {}
abstract getName(): string;
clone() {
const Cls = this.constructor;
return new Cls(this.value);
}
}
In this snippet, Cls is given the type Function and so the compiler complains that: "Cannot use 'new' with an expression whose type lacks a call or construct signature."
Typescript does not use a strict type for the constructor (it just uses Function) and since this is not a constructor, it is not callable with new.
The simple solution is to use a type assertion:
abstract class Base<T> {
constructor(readonly value: T) { }
abstract getName(): string;
clone() {
// Using polymorphic this ensures the return type is correct in derived types
const Cls = this.constructor as new (value: T) => this;
return new Cls(this.value);
}
}
