@uzyn Smart contracts are computer protocols that facilitate, verify, or enforce the negotiation or performance of a contract, or that make a contractual clause unnecessary. @uzyn
@uzyn Smart contracts are computer protocols that facilitate, verify, or enforce the negotiation or performance of a contract, or that make a contractual clause unnecessary.
@uzyn are stored permanently on EVM. Data types Boolean bool Integer int / uint (unsigned) Ethereum address address Bytes and String bytes / string State variables
@uzyn mapping (address => uint) likes; function like(address _friend) public { likes[_friend]++; } Functions and Modifiers modifier onlyOwner { if (msg.sender != owner) throw; _; } function makeAdmin(_candidate) public onlyOwner { admin = _candidate; } The rest of the function goes here Looks pretty much like a JS function.
@uzyn Function Visibilities 1.public a. Visible externally and interally b. Automatically creates accessor. 2.private a. Only visible in current contract Remember, on blockchain, all data is publicly viewable! also internal and external.
@uzyn Roles 1. Issuer a. Able to issue SGDT, after putting up equivalent SGD collateral. b. SGDT <==> SGD exchanger & guarantor. 2. User a. Able to freely transact SGDT. 3.Authority a. Grant license to issuers. http://bit.ly/SGDT-sol
@uzyn pragma solidity ^0.4.2; contract SGDT { /* Public variables of the token */ uint8 public decimals = 2; uint public totalSupply = 0; address public authority; /* This creates an array with all balances */ mapping (address => uint) public balanceOf; mapping (address => uint) public issuedBy; mapping (address => bool) public isIssuer; } Define state variables http://bit.ly/SGDT-sol
@uzyn Issuer functions function issue(uint _value) public onlyIssuer { issuedBy[msg.sender] += _value; balanceOf[msg.sender] += _value; TokenIssued(msg.sender, _value); // Event } Can you work on the redeem() function? http://bit.ly/SGDT-sol
@uzyn User functions // Transfer SGDT function transfer(address _to, uint _value) public { if (balanceOf[msg.sender] < _value) { throw; // Check if the sender has enough } balanceOf[msg.sender] -= _value; // Subtract from the sender balanceOf[_to] += _value; // Add the same to the recipient // Notify anyone listening that this transfer took place Transfer(msg.sender, _to, _value); } http://bit.ly/SGDT-sol
@uzyn Authority functions function addIssuer(address _newIssuer) public onlyAuthority { isIssuer[_newIssuer] = true; } Can you add removeIssuer() function? http://bit.ly/SGDT-sol
uzyn
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