How is data from instance variables in contracts actually stored in the blockchain? Say I have a simple contract like the example Token contract:
contract MyToken {
/* This creates an array with all balances */
mapping (address => uint256) public balanceOf;
/* Initializes contract with initial supply tokens to the creator of the contract */
function MyToken(
uint256 initialSupply
) {
balanceOf[msg.sender] = initialSupply; // Give the creator all initial tokens
}
/* Send coins */
function transfer(address _to, uint256 _value) {
if (balanceOf[msg.sender] < _value) throw; // Check if the sender has enough
if (balanceOf[_to] + _value < balanceOf[_to]) throw; // Check for overflows
balanceOf[msg.sender] -= _value; // Subtract from the sender
balanceOf[_to] += _value; // Add the same to the recipient
}
}
Where is the data in balanceOf stored? How might I be able to get this information without adding a function to the Contract just to return say the balance for an address?