Should a contract be able to specify when it is considered `completed`?

[jeromesimeon]

Currently, there is no way to execute logic at contract termination (or even to indicate what conditions should be met for termination).

While this could be encoded in the logic of the contract itself (with e.g., a state field indicating that the contract is in TERMINATED state), it might be useful to provide a first-class clause for this.

This could look as follows:

contract MyAgreement over MyVariables {
  clause init() { // initialization?
      set state MyState { ... }
  }

  clause purchase(request:Purchase) : PurchaseResponse {
    ...
  }
  clause payment(request:Payment) : PaymentResponse {
    ...
  }

  clause packageReceived(request:DeliveryRequest) : Response {
     terminate()
  } 

  clause terminate() : TerminatedResponse { // finalize? shutdown? completion?
     enforce state.status = "BREACHED" and isAfter(now(), "01/01/2020");
     return TerminatedResponse{}
  }

  clause terminate() : TerminatedResponse { // finalize? shutdown? completion?
     throw ("You can never");
  }

  clause terminate() : TerminatedResponse { // finalize? shutdown? completion?
     return TerminatedResponse{}
  }

 clause terminate(why:String) : TerminatedResponse { // finalize? shutdown? completion?
     return TerminatedResponse{ message: why }
  }
}

Note that after the terminate clause of the contract has been clause, the contract will not accept requests anymore.

[jeromesimeon]

From @mttrbrts Maybe completed is a better terminology than terminated