Exploring TypeScript's Classes and Generics

Question

Exploring TypeScript's Classes and Generics

class Person {
  constructor(public name: string) {}
}

class Manager extends Person {}

class Admin extends Person {}

class School {
  constructor(public name: string) {}
}

function doOperation<T extends Person>(person: T): T {
  return person;
}

let person = doOperation(new Manager("tars"));
let school = doOperation(new School("Harper's"));

One interesting aspect of TypeScript to consider is why no error is thrown in the case where a School instance is passed to doOperation, even though School is not a subclass of Person. Perhaps this behavior can be attributed to both classes (Person and School) having properties with the same name.

typescript typescript-generics

Answer 1

Answer №1

Here's a simplified version of your example that works perfectly in TypeScript:

class Animal {
    constructor(public name: string) {}
}

class Zoo {
    constructor(public name: string) {}
}

const a: Animal = new Zoo("zoo123");

As demonstrated above, TypeScript follows the concept of 'duck typing', where an instance of Zoo can easily be treated as an Animal due to having similar properties.

This approach is advantageous as it promotes flexibility and reduces constraints on type-specific relationships. However, it can also lead to potential errors when calling functions with mismatched types.

The beauty of this feature lies in its ability to create highly generic functions by accepting objects with necessary properties, rather than exact type matches.

Answer 2

Here's a simplified version of your example that works perfectly in TypeScript:

class Animal {
    constructor(public name: string) {}
}

class Zoo {
    constructor(public name: string) {}
}

const a: Animal = new Zoo("zoo123");

As demonstrated above, TypeScript follows the concept of 'duck typing', where an instance of Zoo can easily be treated as an Animal due to having similar properties.

This approach is advantageous as it promotes flexibility and reduces constraints on type-specific relationships. However, it can also lead to potential errors when calling functions with mismatched types.

The beauty of this feature lies in its ability to create highly generic functions by accepting objects with necessary properties, rather than exact type matches.

Exploring TypeScript's Classes and Generics

Answer №1

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