/** Type may not be undefined - instead will be null.  */
type NoVoid<T> = T extends undefined | void ? null : T;
 
namespace Model {
  namespace GetFactory {
    type Refresh = {
      /** Request a refresh for current component. */
      (): void;
      
      /**
      * Request a refresh and again after promise either resolves or rejects.
      * 
      * @returns Promise which resolves, after refresh, to same value as input.
      */
      <T = void>(passthru: Promise<T>): Promise<T>;
  
      /**
      * Request refresh before and after async function.
      * A refresh will occur both before and after the given function.
      * 
      * Any actions performed before first `await` will occur prior to refresh.
      * 
      * @returns Promise which resolves, after refresh, return value.
      */
      <T = void>(invoke: () => Promise<T>): Promise<T>;
    };
  }
 
  type GetFactory<T extends Model, R> = (this: T, current: T, refresh: GetFactory.Refresh) => R;
 
  /** Fetch instance of this class from context. */
  function get <T extends Model> (this: Model.Type<T>, ignore?: true): T;
 
  /** Fetch instance of this class optionally. May be undefined, but will never subscribe. */
  function get <T extends Model> (this: Model.Type<T>, required: boolean): T | undefined;
 
  function get <T extends Model, R> (this: Model.Type<T>, factory: GetFactory<T, Promise<R> | R>): NoVoid<R>;
 
  function get <T extends Model, R> (this: Model.Type<T>, factory: GetFactory<T, null>): NoVoid<R> | null;
}