Venom In Action. Ways of code enhancing

Let's dive into some best practices and good tone coding.

First of all, if your contract deploys some other contracts, it's advisable to have a view method for returning the new contract address:

function getBallotAddress(address owner) 
    external
    view
    responsible
    returns (address)
{
    TvmCell ballotStateInit = tvm.buildStateInit({
        contr: Ballot,
        varInit: {
            _vote: address(this),
            _managerPublicKey: _managerPublicKey,
            _owner: owner
        },
        code: _ballotCode
    });
    return{value: 0, bounce: false, flag: 64} address(tvm.hash(ballotStateInit));
}

As you can see we used some keywords and syntax, that hasn't been discussed before. If the function is marked with responsible keyword, this function will generate an outbound message for the caller with the value, bounce and flag you set. It's preferable to use exactly {value: 0, bounce: false, flag: 64} for this function. Do you remember TIP-3 wallet deploying from our TIP-3 guide? Function deployEmptyWallet is responsible too. That's why we can set a callback parameter there.

The next important point is success/unsuccess callbacks or events. Enhancing your contract with event emitting wouldn't be amiss. Especially when you deploy something or end some case. For example, we can add NewBallot event (when the new ballot is deployed) and VoteAccepted event (after onBallotUsed callback)

Vote.sol

...
contract Vote {
    event NewBallot(address owner);
    event VoteAccepted(address ballot, bool accept);
    ...
    function deployBallot(address owner, address sendRemainingGasTo) external view {
        ...
        emit NewBallot(owner);
        sendRemainingGasTo.transfer({value: 0, flag: 128, bounce: false});
        ...
    }
    ...
    function onBallotUsed(address owner, address sendRemainingGasTo, bool accept) external {
        ...
        emit VoteAccepted(expectedAddress, accept);
        sendRemainingGasTo.transfer({value: 0, flag: 128, bounce: false});
        ...
    }
...
}

There is another small hack for helping frontend developers. You can transfer a small number of nanotons (1,2,3.., etc) to the owner's address. For example:

owner.transfer({value: 1, flag: 1, bounce: false))

Frontend developers can subscribe to incoming transactions to the user's wallet and use these small values to detect contract behavior. For example, we can send 1 nanovenom, if the vote has been accepted

Vote.sol

...
contract Vote {

    ...
    function onBallotUsed(address owner, address sendRemainingGasTo, bool accept) external {
        ...
        owner.transfer({value: 1, flag: 1, bounce: false})
        emit VoteAccepted(expectedAddress, accept);
        sendRemainingGasTo.transfer({value: 0, flag: 128, bounce: false});
    }
...
}l

Pay attention, that events and small value callbacks should be instantiated before any transfers with 128 flag.