2

I'm testing the following contract using Truffle framework and deploying on TestRPC network.

contract MetaCoin {
  mapping (address => uint) balances;

  function MetaCoin() {
    balances[tx.origin] = 10000;
  }

  function sendCoin(address receiver, uint amount) returns(bool sufficient) {
    if (balances[msg.sender] < amount) return false;
    balances[msg.sender] -= amount;
    balances[receiver] += amount;
    return true;
  }

  function getBalanceInEth(address addr) returns(uint){
    return ConvertLib.convert(getBalance(addr),2);
  }

  function getBalance(address addr) returns(uint) {
    return balances[addr];
  }
}

I load it up in the browser and it seems to work. What I wonder is if it is possible to change the coinbase dynamically.

For example, after I've send some MetaCoins from user1 to user2 then I want to change the coinbase to user2 and reload the app to show me the MetaCoins balance of user2.

How can I achieve that?

  • Can you define "coinbase"? It has a specific definition in a mining context that I think you may be misuing – Aakil Fernandes Apr 20 '16 at 22:15
  • getBalance and getBalanceInEth might be declared constant. Then you can call them for free, fast and with any address from your Dapp. – jbaylina Apr 21 '16 at 3:12
  • 1
    @jbaylina you don't have to declare it constant, you can use getBalance.call() to achieve the same result. It would be better style to make it constant, though – Tjaden Hess Apr 21 '16 at 13:32
3

With coinbase I guess you mean default address your web-application uses? Testrpc initialized by default 10 accounts. If you want to switch account in the javascript frontend, you can change the default account using the web3 api: https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethdefaultaccount

Alternatively, if you have an separate authentication mechanism in our web-application (for example a social login), you could associatie an ethereum address with a user. How and if depends on how your dapp/application is set up.

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