Intro to Nebulas for Ethereum Smart Contract Developers

accountstate

curl -X POST \
  http://localhost:8685/v1/user/accountstate \
  -H 'content-type: application/json' \
  -d '{ "address": "n1Vg9Ngvi3vXo5f59diW4MK8XXger36weUm" }'

{"result":{"balance":"1000000000000000000","nonce":"0","type":87}}

bignumber.js

const BigNumber = require("bignumber.js");

Number.MAX_SAFE_INTEGER;     // 9007199254740991
Number.MAX_SAFE_INTEGER + 1; // 9007199254740992
Number.MAX_SAFE_INTEGER + 2; // 9007199254740992

const number = new BigNumber(Number.MAX_SAFE_INTEGER);
number.plus(2).toString();   // "9007199254740993"

call

curl -X POST \
  http://localhost:8685/v1/user/call \
  -H 'content-type: application/json' \
  -d '{
  "from": "n1QA4usgq7sJbcM5LEkJWpgyNBcKtVEULFf",
  "to": "n1mQoB6HneRuu7c15Sy79CPHv8rhkNQinJe",
  "value": "0",
  "gasPrice": "1000000",
  "gasLimit": "2000000",
  "contract": { "function": "myView", "args": "[100]" }
}
'

{
  "result": {
    "result": "{\"key\":\"value\"}",
    "execute_err": "",
    "estimate_gas": "20126"
  }
}

max.sol

uint max = 2**256 - 1; // 115792089237316195423570985008687907853269984665640564039457584007913129639935
max + 1; // 0

ownable.js

class Ownable {
  constructor() {
    LocalContractStorage.defineProperty(this, "storage");
  }

  init() {
    this.owner = Blockchain.transaction.from;
  }
}

ownable.sol

contract Ownable {
  address owner;

  constructor() public {
    owner = msg.owner;
  }
}

safe-max.sol

import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/math/SafeMath.sol";

using SafeMath for uint256;

uint max = 2**256 - 1;
max.add(1); // VM error

structure.js

class StandardToken {
  init() {
    // ...
  }
}

module.exports = StandardToken;

structure.sol

contract Crowdsale is MintedCrowdsale, CappedCrowdsale {
  constructor(uint256 _rate, address _wallet, ERC20 _token) public {
    // ...
  }

  function () public payable {
    buyTokens(msg.sender);
  }

  function buyTokens(address _beneficiary) public payable {
    // ...
  }
}

test.sol

pragma solidity 0.4.24;

import "truffle/Assert.sol";
import "../contracts/Ownable.sol";


contract OwnableTest {
    Ownable ownable;

    function beforeEach() public {
        ownable = new Ownable();
    }

    function testConstructor() public {
        Assert.equal(ownable.owner(), address(this), "owner address is invalid");
    }

    // ...
}

transaction

curl -X POST \
  http://localhost:8685/v1/admin/transactionWithPassphrase \
  -H 'content-type: application/json' \
  -d '{
  "transaction": {
    "from": "n1Vg9Ngvi3vXo5f59diW4MK8XXger36weUm",
    "to": "n1gQgDb72yL1vrRcUEP3219ytcZGxEmcc9u",
    "value": "0",
    "nonce": 59,
    "gasPrice": "1000000",
    "gasLimit": "2000000",
    "contract": { "function": "myMethod", "args": "" }
  },
  "passphrase": "passphrase"
}
'

{
    "result": {
        "txhash": "36a61c6413e71387f34b0b442e73d2a8b54646917c58338166b0473292c0b26d",
        "contract_address": ""
    }
}

transfer-value.js

Blockchain.transfer(address, value);

transfer-value.sol

address(address).transfer(value);

tx-props.js

Blockchain.transaction.from    // sender address (string)
Blockchain.transaction.value   // number of Wei sent (string)
Blockchain.block.timestamp     // current block timestamp (number)

tx-props.sol

msg.sender          // sender address (address)
msg.value           // number of Wei sent (uint256)
block.timestamp     // current block timestamp (uint256)

verify.js

Blockchain.verifyAddress(address);

visibility.js

class Visibility {
  function visible() {
   this._hidden();
  }

  function _hidden() {}
}

visibility.sol

contract Visibility {
    function visible() pure public {}

    function hiddenFromOthers() pure private {}

    function visibleOnlyForFunctions() pure external {}

    function visibleForChildContracts() pure internal {}
}