Type alias Like<T, L>

Associates a type T with a loosely typed representation L. Loose type representations are modeled as a phantom method likeType?(like: L): void whose argument type is the loosely typed representation of T. Because the likeType method is optional, values of type T are assignable to type Like<T, L>, and vice versa.

The preferred way to associate loose type representations with a custom class is to declare a likeType?(like: L): void method on the class itself. The Like type is used to inject a phantom likeType method into an existing type. This enables ad hoc loose types to be declared without needing to change the declaration of the strict type.

Example

Ad hoc number coercion

const NumberLike: FromLike<Like<number, string | boolean>> = {
  fromLike(value: number | string | boolean): number {
    return Number(value);
  },
};

NumberLike.fromLike("42") // yields 42
NumberLike.fromLike(true) // yields 1
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Example

Using an ad hoc conversion with a @Property fastener

class Person {
  @Property({valueType: NumberLike})
  readonly age!: Property<Like<number, string | boolean>>;
}

const person = new Person();
person.age.setValue("42");
person.age.value // yields 42
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