Consuming Explicitly Managed Resources

EMR

import { main, type Operation, resource, until } from "@effection/effection";

class Thing {
  constructor(public num: number) {}
  async [Symbol.asyncDispose]() {
    console.log(`[${this.num}]`, 'Adieu!');
  }
}

export function using<T extends AsyncDisposable>(value: T): Operation<T> {
  return resource(function*(provide) {
    try {
      yield* provide(value);
    } finally {
      yield* until(value[Symbol.asyncDispose].call(value) as Promise<void>);
    }
  })
}

await main(function*() {
  let one = yield* using(new Thing(1));
  let two = yield* using(new Thing(2));

  console.log({ one, two });
});

//=> { one: Thing { num: 1 }, two: Thing { num: 2 } }
//=> [2] Adieu!
//=> [1] Adieu!