CODEWITHSUNDEEP
typescript
Ohgodwhy
Ohgodwhy

Reputation: 50777

Argument must extend class

I'm moving to Typescript for a variety of reasons, and so far I'm supremely happy with it.

One of the issues that I've ran into is verifying that an argument passed to a function extends another class.

For instance:

class Foo {
    public $xyz
}

class Bar {
    constructor(model: extends Foo)
}

class Baz extends Foo {}

Many classes can extend foo, besides Baz, but they all have the same properties. I need to ensure that the class being passed to the model argument of the constructor Bar correctly extends Foo.

How can I achieve this?

(please forgive the terrible psuedo-code above)

If my approach is wrong, I'd love to hear what I could do to solve that problem as well.

Upvotes: 1

Views: 471

Answers (1)

Igor
Igor

Reputation: 62213

constructor(model: Foo)

Is what you are looking for. This states that the passed instance model is of type Foo or inherits from Foo.

The keyword extends can only be used in type declarations to denote that the type extends (inherits from) another type.

See also Classes documentation.

Upvotes: 1

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