Abstract methods

[RyanCavanaugh]

As a continuation of #6, which allows the abstract modifier on class declarations, we should extend this to class methods.

Relevant points:

• An abstract method may only be declared in an abstract class
• abstract methods may not have implementations
• abstract methods may not be private, but may be protected
• It is an error to invoke an abstract method via super in a derived clas
• Fields may not be abstract
• Property getters / setters may not be abstract
• A class must be marked abstract if it does not overwrite all of its abstract base class's abstract methods
• All overloads of a method must have, or not have, the abstract modifier
• Static methods may not be abstract
• abstract modifier must come after public or protected modifier

Secondary clarifications:

• abstract has no impact on assignability / subtype / supertype relations

[ddotlic]

I was just about to comment on asking for something like this, it's not yet reached a pain point in the project I'm working on (due to the size) but might soon.

I simply want to make sure I don't forget to override an abstract method in a base (base...) class and that's it. The feature can be implemented as rigidly as you want as long as it helps me code better - meaning I really don't care about other subtleties as mentioned in #6 though I'm aware some are important to clarify before implementation begins as it clashes with some of the JS oddities.

TypeScript is shaping up to be a really great language (seeing what you've started with - JavaScript - can't be considered great unless you're heavily drunk 😉 )

[CKGrafico]

Anything new about this?

[mhegazy]

@aozgaa is looking into this

[aozgaa]

I've posted an updated proposal in #3578 and made a pull request in #3579. Take a look and let me know what you think!

[tinganho]

Static methods may not be abstract

@RyanCavanaugh Is there a way I can write a contract where on extending class's static methods has a certain signature?

export abstract class ComposerContent<Props, States, T> extends ReactComposerComponent<Props, States> {
   static abstract fetch(): string;
}

React seem to want to put a lot of stuff as static members(GrahpQL, Relay). And I want some autocompletion on those only by extending a class.

[RyanCavanaugh]

Is there a way I can write a contract where on extending class's static methods has a certain signature?

There isn't. Let us know if you see other cases where this would be useful - we generally didn't see a need for it.