function versioned(version: string) { return function (constructor: Function) { // add a version on the prototype so instances can read it (constructor as any).prototype.version = version; const original = constructor as any; const newConstructor: any = function (...args: any[]) { console.log(`Creating instance of ${original.name} v${version}`); return new original(...args); }; newConstructor.prototype = original.prototype; return newConstructor; }; } @versioned('1.0.0') class ApiClient { fetchData() { console.log('Fetching data...'); } } const client = new (ApiClient as any)(); console.log((client as any).version); client.fetchData();