I found success in deploying Crowdsale.sol on ropsten testnet but I am finding trouble with TimedCrowdsale.sol
I am using OpenZeppelin contracts of TimedCrowdsale.sol, SafeMath.sol, Crowdsale.sol, ERC20.sol and ERC20Basic.sol
I am able to compile TimedCrowdsale.sol.
The error message is "This contract does not implement all functions and thus cannot be created."
Am I doing something wrong? Any help would be greatly appreciated.
My code:
browser/TimedCrowdsale.sol
pragma solidity ^0.4.23;
import './SafeMath.sol';
import './Crowdsale.sol';
/**
* @title TimedCrowdsale
* @dev Crowdsale accepting contributions only within a time frame.
*/
contract TimedCrowdsale is Crowdsale {
using SafeMath for uint256;
uint256 public openingTime;
uint256 public closingTime;
/**
* @dev Reverts if not in crowdsale time range.
*/
modifier onlyWhileOpen {
// solium-disable-next-line security/no-block-members
require(block.timestamp >= openingTime && block.timestamp <= closingTime);
_;
}
/**
* @dev Constructor, takes crowdsale opening and closing times.
* @param _openingTime Crowdsale opening time
* @param _closingTime Crowdsale closing time
*/
constructor(uint256 _openingTime, uint256 _closingTime) public {
// solium-disable-next-line security/no-block-members
require(_openingTime >= block.timestamp);
require(_closingTime >= _openingTime);
openingTime = _openingTime;
closingTime = _closingTime;
}
/**
* @dev Checks whether the period in which the crowdsale is open has already elapsed.
* @return Whether crowdsale period has elapsed
*/
function hasClosed() public view returns (bool) {
// solium-disable-next-line security/no-block-members
return block.timestamp > closingTime;
}
/**
* @dev Extend parent behavior requiring to be within contributing period
* @param _beneficiary Token purchaser
* @param _weiAmount Amount of wei contributed
*/
function _preValidatePurchase(
address _beneficiary,
uint256 _weiAmount
)
internal
onlyWhileOpen
{
super._preValidatePurchase(_beneficiary, _weiAmount);
}
}
browser/SafeMath.sol
pragma solidity ^0.4.23;
/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
/**
* @dev Multiplies two numbers, throws on overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
if (a == 0) {
return 0;
}
c = a * b;
assert(c / a == b);
return c;
}
/**
* @dev Integer division of two numbers, truncating the quotient.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
// assert(b > 0); // Solidity automatically throws when dividing by 0
// uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return a / b;
}
/**
* @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
assert(b <= a);
return a - b;
}
/**
* @dev Adds two numbers, throws on overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
c = a + b;
assert(c >= a);
return c;
}
}
browser/Crowdsale.sol
pragma solidity ^0.4.23;
import './ERC20.sol';
import './SafeMath.sol';
/**
* @title Crowdsale
* @dev Crowdsale is a base contract for managing a token crowdsale,
* allowing investors to purchase tokens with ether. This contract implements
* such functionality in its most fundamental form and can be extended to provide additional
* functionality and/or custom behavior.
* The external interface represents the basic interface for purchasing tokens, and conform
* the base architecture for crowdsales. They are *not* intended to be modified / overriden.
* The internal interface conforms the extensible and modifiable surface of crowdsales. Override
* the methods to add functionality. Consider using 'super' where appropiate to concatenate
* behavior.
*/
contract Crowdsale {
using SafeMath for uint256;
// The token being sold
ERC20 public token;
// Address where funds are collected
address public wallet;
// How many token units a buyer gets per wei
uint256 public rate;
// Amount of wei raised
uint256 public weiRaised;
/**
* Event for token purchase logging
* @param purchaser who paid for the tokens
* @param beneficiary who got the tokens
* @param value weis paid for purchase
* @param amount amount of tokens purchased
*/
event TokenPurchase(
address indexed purchaser,
address indexed beneficiary,
uint256 value,
uint256 amount
);
/**
* @param _rate Number of token units a buyer gets per wei
* @param _wallet Address where collected funds will be forwarded to
* @param _token Address of the token being sold
*/
constructor(uint256 _rate, address _wallet, ERC20 _token) public {
require(_rate > 0);
require(_wallet != address(0));
require(_token != address(0));
rate = _rate;
wallet = _wallet;
token = _token;
}
// -----------------------------------------
// Crowdsale external interface
// -----------------------------------------
/**
* @dev fallback function ***DO NOT OVERRIDE***
*/
function () external payable {
buyTokens(msg.sender);
}
/**
* @dev low level token purchase ***DO NOT OVERRIDE***
* @param _beneficiary Address performing the token purchase
*/
function buyTokens(address _beneficiary) public payable {
uint256 weiAmount = msg.value;
_preValidatePurchase(_beneficiary, weiAmount);
// calculate token amount to be created
uint256 tokens = _getTokenAmount(weiAmount);
// update state
weiRaised = weiRaised.add(weiAmount);
_processPurchase(_beneficiary, tokens);
emit TokenPurchase(
msg.sender,
_beneficiary,
weiAmount,
tokens
);
_updatePurchasingState(_beneficiary, weiAmount);
_forwardFunds();
_postValidatePurchase(_beneficiary, weiAmount);
}
// -----------------------------------------
// Internal interface (extensible)
// -----------------------------------------
/**
* @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use super to concatenate validations.
* @param _beneficiary Address performing the token purchase
* @param _weiAmount Value in wei involved in the purchase
*/
function _preValidatePurchase(
address _beneficiary,
uint256 _weiAmount
)
internal
{
require(_beneficiary != address(0));
require(_weiAmount != 0);
}
/**
* @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
* @param _beneficiary Address performing the token purchase
* @param _weiAmount Value in wei involved in the purchase
*/
function _postValidatePurchase(
address _beneficiary,
uint256 _weiAmount
)
internal
{
// optional override
}
/**
* @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
* @param _beneficiary Address performing the token purchase
* @param _tokenAmount Number of tokens to be emitted
*/
function _deliverTokens(
address _beneficiary,
uint256 _tokenAmount
)
internal
{
token.transfer(_beneficiary, _tokenAmount);
}
/**
* @dev Executed when a purchase has been validated and is ready to be executed. Not necessarily emits/sends tokens.
* @param _beneficiary Address receiving the tokens
* @param _tokenAmount Number of tokens to be purchased
*/
function _processPurchase(
address _beneficiary,
uint256 _tokenAmount
)
internal
{
_deliverTokens(_beneficiary, _tokenAmount);
}
/**
* @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
* @param _beneficiary Address receiving the tokens
* @param _weiAmount Value in wei involved in the purchase
*/
function _updatePurchasingState(
address _beneficiary,
uint256 _weiAmount
)
internal
{
// optional override
}
/**
* @dev Override to extend the way in which ether is converted to tokens.
* @param _weiAmount Value in wei to be converted into tokens
* @return Number of tokens that can be purchased with the specified _weiAmount
*/
function _getTokenAmount(uint256 _weiAmount)
internal view returns (uint256)
{
return _weiAmount.mul(rate);
}
/**
* @dev Determines how ETH is stored/forwarded on purchases.
*/
function _forwardFunds() internal {
wallet.transfer(msg.value);
}
}
browser/ERC20.sol
pragma solidity ^0.4.23;
import "./ERC20Basic.sol";
/**
* @title ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/20
*/
contract ERC20 is ERC20Basic {
function allowance(address owner, address spender)
public view returns (uint256);
function transferFrom(address from, address to, uint256 value)
public returns (bool);
function approve(address spender, uint256 value) public returns (bool);
event Approval(
address indexed owner,
address indexed spender,
uint256 value
);
}
browser/ERC20Basic.sol
pragma solidity ^0.4.23;
/**
* @title ERC20Basic
* @dev Simpler version of ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/179
*/
contract ERC20Basic {
function totalSupply() public view returns (uint256);
function balanceOf(address who) public view returns (uint256);
function transfer(address to, uint256 value) public returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
}
