Generics, almost...

[benbenbenbenbenben]

I don't know if this is of interest, but you can get marginally closer to generic mixins by using a swift inspired associated type kinda of trick:

abstract class Runable<T> {
    context?: T; // Later we can lookup typeof Foo["context"]
    protected abstract run(ctx: typeof this["context"]): Promise<void>
}

export class zip extends Mixin(Runable<{ baseDir: string }>) {
    paths: string[];
    constructor(...paths: string[]) {
        super();
        this.paths = paths;
        // FWIW if you can attached .run here it *IS* type inferred (but zip would be incomplete less you drop abstract)...
        // this.run = (ctx) => this.doRun(ctx);
    }

    // The Normal Way:
    // a type annotation is needed - but the LSP will infill with automatic fix!
    protected async run(ctx: typeof this["context"]): Promise<void> {
        console.log("Zipping", this.paths, "in", ctx.baseDir);
    }
}