Add abstract support to new

[LongTengDao]

Search Terms

abstract new

Suggestion

type X = { abstract new () :object };

Use Cases

To ensure an fn arg is an constructor but can't directly construct.

Examples

declare function fn (constructor :{ abstract new () :object }) :void;

fn(               {                             }); // error, must be class
fn(         class {                             }); // error, must be class and can't as new.target
fn(         class { protected constructor () {} }); // error, must be class and can't as new.target even in it self
fn(abstract class {                             }); // right
fn(abstract class { protected constructor () {} }); // right

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[DanielRosenwasser]

Seems like @rbuckton's #36392 fixes this. I don't know if I can technically mark this as a duplicate of #26829 or #35576 because it's not clear that either of them have suggested the specific feature.