The Resumable trait is almost identical to the Stoppable trait that we covered in the previous example.
It adds one important feature which is the ability for the owner to resume a stopped contract.
The Stoppable trait by itself may be a little dangerous because the owner cannot change their mind. If you're not sure which trait to use, use this one.
This trait implicitly adds the Ownable and Stoppable traits. Note that the Ownable trait doesn't allow the owner to transfer ownership to a different owner. To allow changing ownership, also add the OwnableTransferable trait.
Define state variables named owner: Address and stopped: Bool and call self.requireNotStopped() on actions that should be stopped.
// this trait has to be imported
import "@stdlib/stoppable";
import "@stdlib/ownable";
import "@stdlib/deploy";
// the Stoppable trait allows the owner to stop the contract which can limit certain actions
contract Counter with Deployable, Stoppable {
owner: Address; // The Stoppable trait requires you to add this exact state variable
stopped: Bool; // The Stoppable trait requires you to add this exact state variable
val: Int as uint32;
init() {
self.owner = sender(); // we can initialize owner to any value we want, the deployer in this case
self.stopped = false;
self.val = 0;
}
// this message will only work until the contract was stopped
receive("increment") {
self.requireNotStopped();
self.val = self.val + 1;
}
get fun value(): Int {
return self.val;
}
// receive("Stop") is added automatically to allow owner to stop the contract
// get fun stopped(): Bool is added automatically to query if contract is stopped
// get fun owner(): Address is added automatically to query who the owner is
}