Alternative TypeScript-DCI money transfer example

TransferMoney.ts

/**
 * Transfer Money use case
 */
function TransferMoney(sourceAcct: Account, destinationAcct: Account, amount: number) {

    //bind the objects to their roles
    SourceAccount <- sourceAcct;
    DestinationAccount <- destinationAcct;
    Amount <- amount;
    
    //do the transfer
    SourceAccount.transferOut();
    
    role SourceAccount {
        transferOut() {
            if (self.getBalance() < Amount) {
                throw new Error('Insufficient funds');
            }
            DestinationAccount.transferIn();
        }
    }

    role DestinationAccount {
        transferIn() {
            self.increaseBalance(Amount);
        }
    }

    role Amount {}
}

/**
 * Bank account class
 */
class Account
{
    private balance: number = 0;

    increaseBalance(amount: number) {
        this.balance += amount;
    }

    decreaseBalance(amount: number) {
        this.balance -= amount;
    }

    getBalance(): number {
        return this.balance;
    }
}


//Run the use case

var sourceAccount = new Account();
sourceAccount.increaseBalance(20);

var destinationAccount = new Account();
destinationAccount.increaseBalance(10);

//Transfer 10 dollars (or whatever the currency is) from the source account to the destination account
TransferMoney(sourceAccount, destinationAccount, 10);