Assignment operator overloading in TypeScript

Question

I am writing a set of TypeScript classes that use inheritance to maintain a "Type" hierarchy (for want of a better phrase).

Say for example I have a base class...

class Parent {
}

and then I derive other classes from this...

class Child extends Parent {
}

So far so good...but lets say, now I want to be able to assign something to my Child class directly, like so:

private xyz: Child = "Foo Bar";

TypeScript currently throws up a compiler/syntax error...

Cannot convert string to Child

If I can assign strings to String (which is equally, just a prototype, as is my Child class), how do I go about overloading the assignment operator of my class to accept strings?

EDIT: I tried this...

class Child extends Parent implements String {
}

...still, it does not have the desired effect.

Speaking from a C# background, I guess I'm trying to achieve the equivalent of...

public static implicit operator Child(string value
{
    return new Child(value);
}

Fenton · Accepted Answer · 2013-02-06 11:21:33Z

2

In a class-based language you would normally accept parameters in the constructor, like this:

class Parent {
}

class Child extends Parent {
    constructor(private someProp: string) {
        super();
    }
}

var child = new Child("Foo Bar");

answered Feb 6, 2013 at 11:21

Fenton

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2 Comments

Matthew Layton Over a year ago

Speaking from a C# background, is there no way you can do the equivalent of public static implicit operator Child(string value) {} ?

Fenton Over a year ago

This feature doesn't exist in TypeScript at the moment - the implicit and explicit conversions are a neat feature in C#. You could suggest it to the TypeScript team: typescript.codeplex.com

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