Post your code here for the openzeppelin templates assignment.
5 Likes
Here is my solution:
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract ERC20PresetMinterPauser is Context, AccessControl, ERC20Burnable, ERC20Pausable {
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAPPER_ROLE = keccak256("CAPPER_ROLE");
using SafeMath for uint256;
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAPPER_ROLE, _msgSender());
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
}
// Sets the new cap of the token
function setCap(uint256 newCap) public {
// Make sure the caller has the capper role
require(hasRole(CAPPER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have capper role to change the cap");
// Make sure that the total supply will not exceed the new cap
require(totalSupply() >= newCap, "ERC20Capped: cap exceeded");
// Set the new cap
_cap = newCap;
}
}
1 Like
I implemented an increaseCap function so that address with role CAPCHEF can only increase the cap, but not decrease, as I suspect, that if it is possible to decrease the cap when already lots of tokens are circulating, a too big of a decrease in max cap would lead to bigger problems. No?
Of course, we could check that the new cap is >= to the totalSupply(). Hm, anyway, the function is a bit funny. 
ERC20 with Mint, Pauser and Cap plus increaseCap function
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract TomsToken is Context, AccessControl, ERC20Burnable, ERC20Pausable {
//vars from ERC20Capped
using SafeMath for uint256;
uint256 private _cap;
//------------------------------------------
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
//New role capChef
bytes32 public constant CAPCHEF_ROLE = keccak256("CAPCHEF_ROLE");
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20("TomsToken", "TT") {
//from ERC20Capped
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
//---------------------------------------------
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAPCHEF_ROLE, _msgSender());
}
//New function to allow increase of Cap
function increaseCap(uint256 amount) public {
//Checks if role is CAPCHEF
require(hasRole(CAPCHEF_ROLE, _msgSender()), "Only CAPCHEF can increase Cap!");
//increases cap by given amount
_cap = _cap.add(amount);
}
//from ERC20Capped
function cap() public view virtual returns (uint256) {
return _cap;
}
//---------------------------------------------
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
//from ERC20Capped
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
//---------------------------
}
}
Update:
Right, just saw it in the solution video. We have to check that newCap is bigger or equal to 0.
Still I ask myself what would happen if cap gets set below totalSupply while Tokens are in user wallets?
1 Like
Here is my solution!
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import ".../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import ".../node_modules/@openzeppelin/contracts/utils/Context.sol";
import ".../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import ".../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import ".../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract ERC20PresetMinterPauserCapCap is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAP_CHANGER_ROLE = keccak256("CAP_CHANGER_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAP_CHANGER_ROLE, _msgSender());
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauserCap: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauserCap: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauserCap: must have pauser role to unpause");
_unpause();
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
function setCap(uint256 newCap) public virtual returns(uint256) {
require(hasRole(CAP_CHANGER_ROLE, _msgSender()), "ERC20PresetMinterPauserCap: must have cap changer role to set cap");
require(newCap > 0, "ERC20PresetMinterPauserCap: new cap is zero");
require(newCap >= _totalSupply, "ERC20PresetMinterPauserCap: new cap must be greater than or equal to current total supply");
_cap = newCap;
return _cap;
}
/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
}
}
1 Like
I had a similar thought working through this assignment. I think it makes sense to add the additional check you mentioned to make sure that the new cap is greater than or at least equal to the current total supply. Without it, we still wouldnāt be able to mint new tokens, but I would imagine it could lead to bugs if you end up referencing the cap and _totalSupply in other functions.
1 Like
Here is my code
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
* - a capper role that allows to change the cap on the token
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter, capper and pauser
* roles, as well as the default admin role, which will let it grant both minter, capper
* and pauser roles to other accounts.
*/
contract MyToken is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAPPER_ROLE = keccak256("CAPPER_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint cap) public ERC20(name, symbol) {
require(cap > 0, "ERC20Capped: cap is 0");
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAPPER_ROLE, _msgSender());
_cap = cap;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual{
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public virtual view returns (uint256) {
return _cap;
}
/**
* @dev Changes the cap on the token's total supply.
*/
function changecap(uint newcap) public virtual returns (uint256) {
require(newcap >= totalSupply(), "ERC20Capped: can't lower cap below current supply");
require(hasRole(CAPPER_ROLE, _msgSender()), "ERC20Capped: must have capper role to change cap");
_cap = newcap;
return _cap;
}
}
1 Like
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract ERC20CappedPresetMinterPauser is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAPPER_ROLE = keccak256("CAPPER_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
require(cap_ > 0, "ERC20Capped: cap is 0");
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAPPER_ROLE, _msgSender());
_cap = cap_;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
/**
* @dev sets the cap
*/
function setCap(uint256 cap_) public virtual {
require(hasRole(CAPPER_ROLE, _msgSender()), "ERC20CappedPresetMinterPauser: must have capper role to set cap");
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
}
}
1 Like
My solution:
https://github.com/thecil/eth_prog_201/tree/main/tokenOpenZep
Iām sure that Iām missing something
The unit test validate the proper functionality of the functions and contract.
Carlos Z
2 Likes
Hey @thecil
I donāt think you are missing something.
The idea was to create a contract that had also the mint and pause functionalities, but you imported ERC20PresetMinterPauser.sol directly 
Why code something from scratch when you can import it? I like your mentality man.
Also great tests!
Cheers,
Dani
2 Likes
This is my solution.
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "./AccessControl.sol";
import "./Context.sol";
import "./ERC20.sol";
import "./ERC20Burnable.sol";
import "./SafeMath.sol";
import "./ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract ERC20MinterPauserCapped is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
uint256 private _cap;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAP_ROLE = keccak256("CAP_ROLE");
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
require(cap_ > 0, "ERC20MinterPauserCapped: Cap is 0");
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAP_ROLE, _msgSender());
_cap = cap_;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20MinterPauserCapped: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20MinterPauserCapped: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20MinterPauserCapped: must have pauser role to unpause");
_unpause();
}
/**
* @dev Modifies the maximum supply of the token
*
* Requirements:
*
* - the caller must have the `CAP_ROLE`.
*/
function changeCap(uint256 newCap_) public virtual {
require(hasRole(CAP_ROLE, _msgSender()), "ERC20MinterPauserCapped: must have cap role to modify maximum supply");
// Make sure that the total supply will not exceed the new cap
require(totalSupply() >= newCap_, "ERC20MinterPauserCapped: cap exceeded");
_cap = newCap_;
}
function cap() public view virtual returns (uint256) {
return _cap;
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20MinterPauserCapped: cap exceeded");
}
}
}
1 Like
Here is my Solution
Code
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract MyToken is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
uint256 private _cap;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAP_CHANGER_ROLE = keccak256("CAP_CHANGER_ROLE");
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
require(cap_ > 0, "MyToken: Cap must be > 0");
_cap = cap_;
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAP_CHANGER_ROLE, _msgSender());
}
function changeCap(uint256 cap_) public virtual {
require(hasRole(CAP_CHANGER_ROLE, _msgSender()), "MyToken: Must have cap changer role to update cap");
require(cap_ > 0, "MyToken: Cap must be > 0");
_cap = cap_;
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "MyToken: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "MyToken: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "MyToken: must have pauser role to unpause");
_unpause();
}
/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "MyToken: cap exceeded");
}
}
}
1 Like
Two template contracts met in the woods: copyā¦or inheritā¦and I took the one less traveled by.
I couldnāt multiple-inherit ERC20Capped.sol because its ā_capā is private, so I had to scavange parts.
Thatās always the trick, isnāt it.
Hereās a few more:
pragma solidity >=0.6.0 <0.8.0;
// SPDX-License-Identifier: MIT
import "@openzeppelin/contracts/presets/ERC20PresetMinterPauser.sol";
contract PresetMinterPauserCapped is ERC20PresetMinterPauser {
bytes32 public constant CAPPER_ROLE = keccak256("CAPPER_ROLE");
uint256 private _cap;
event recapped(uint256);
constructor(uint256 cap_)
ERC20PresetMinterPauser("PresetMinterPauserCapped", "PMPC"){
_setupDecimals(8);
_setupRole(CAPPER_ROLE, _msgSender());
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
}
function _beforeTokenTransfer(address from, address to, uint256 amount
) internal virtual override(ERC20PresetMinterPauser) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(SafeMath.add(super.totalSupply(),amount) <= _cap,
"PresetMinterPauserCapped: cap exceeded");
}
}
function notReallyCapped(uint256 newFakeCap) public returns (uint256){
require(hasRole(CAPPER_ROLE, _msgSender()),
"PresetMinterPauserCapped: must have capper role to re-cap");
_cap = newFakeCap;
emit recapped(newFakeCap);
return newFakeCap;
}
function cap() public view returns (uint256) {
return _cap;
}
}
2 Likes
Hi,
Here is my solution.
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/math/SafeMath.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract CapChangeChallengeToken is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAPCHANGER_ROLE = keccak256("CAPCHANGER_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint cap_) ERC20("CapChangeChallengeToken","CCCT") {
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(CAPCHANGER_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
_mint(_msgSender(),1250);
}
event TokenCapUpdated(address indexed _changedBy, uint _prevCap, uint _newCap);
/**
* @dev Changes the Cap
*/
function capChange(uint _newCap) public returns (uint256){
require(hasRole(CAPCHANGER_ROLE, _msgSender()), "ERC20CCCToken: must have CAPCHANGER_ROLE role to change cap");
require(_newCap != _cap,"The cap is already set to that value");
require(_newCap > 0, "ERC20: cap cannot be 0");
uint _prevCap = _cap;
_cap = _newCap;
emit TokenCapUpdated(_msgSender(),_prevCap,_newCap);
return _newCap;
}
/**
* @dev Grant Cap Change Role
*/
function grantCapChangeRole(address _addressToGrant) public returns (bool success){
//the address calling this must be admin already or the below will fail.
if (_addressToGrant == address(0)){
//"Address must be non-zero");
return false;
}
grantRole(CAPCHANGER_ROLE,_addressToGrant);
return true;
}
/**
* @dev Revoke Cap Change Role
*/
function revokeCapChangeRole(address _addressToRevoke) public returns (bool success){
//the address calling this must be admin already or the below will fail.
if (_addressToRevoke == address(0)){
//"Address must be non-zero");
return false;
}
require(hasRole(CAPCHANGER_ROLE, _addressToRevoke),"Account does not have role to revoke");
revokeRole(CAPCHANGER_ROLE,_addressToRevoke);
return true;
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override (ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
//Added the below code to ensure cap not exceeded when minting.
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
}
1 Like
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract MyToken is Context, AccessControl, ERC20Burnable, ERC20Pausable {
using SafeMath for uint256;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAPCHANGE_ROLE = keccak256("CAP CHANGE_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAPCHANGE_ROLE, _msgSender());
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
}
function returnCap() public view virtual returns (uint256) {
return _cap;
}
function changeCap(uint256 cap_) public {
require(hasRole(CAPCHANGE_ROLE, _msgSender()), "MaxToken: must have capchange role to mint");
require(cap_ >= totalSupply(), "ERC20Capped: cap should be higher or equal than the total supply");
_cap = cap_;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= returnCap(), "ERC20Capped: cap exceeded");
}
}
}
1 Like
My solution:
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/presets/ERC20PresetMinterPauser.sol";
import "../node_modules/@openzeppelin/contracts/math/SafeMath.sol";
contract MyToken is ERC20PresetMinterPauser {
using SafeMath for uint256;
bytes32 public constant CAP_OWNER_ROLE = keccak256("CAP_OWNER_ROLE");
uint256 private _cap;
constructor(string memory name, string memory symbol, uint256 cap_) ERC20PresetMinterPauser(name, symbol) {
require(cap_ > 0, "MyToken: cap is 0");
_setupRole(CAP_OWNER_ROLE, _msgSender());
_cap = cap_;
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
/**
* @dev Sets new cap on the token's total supply.
*/
function setCap(uint256 _newCap) public virtual {
require(hasRole(CAP_OWNER_ROLE, _msgSender()), "MyToken: Sender must be a cap owner to change the cap");
require(_newCap > 0, "MyToken: cap is 0");
_cap = _newCap;
}
/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "MyToken: cap exceeded");
}
}
}
1 Like
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract ERC20PresetMinterPauser is Context, AccessControl, ERC20Burnable, ERC20Pausable {
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAP_ROLE = keccak256("CAP_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` to the
* account that deploys the contract.
*
* See {ERC20-constructor}.
*/
constructor(string memory name, string memory symbol, uint256 cap_) public ERC20(name, symbol) {
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAP_ROLE, _msgSender());
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
function setCap(uint256 cap_) public {
require(hasRole(CAP_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have cap role to change cap");
require(cap_ >= totalSupply(), "ERC20Cap: cap must be greater or equal than totalSupply");
_cap = cap_;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply() + amount <= cap(), "ERC20Capped: cap exceeded");
}
}
}
1 Like
Here is my code for the Openzeppelin Extension Assignment:
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../node_modules/@openzeppelin/contracts/access/AccessControl.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20Pausable.sol";
/**
* @dev {ERC20} token, including:
*
* - ability for holders to burn (destroy) their tokens
* - a minter role that allows for token minting (creation)
* - a pauser role that allows to stop all token transfers
*
* This contract uses {AccessControl} to lock permissioned functions using the
* different roles - head to its documentation for details.
*
* The account that deploys the contract will be granted the minter and pauser
* roles, as well as the default admin role, which will let it grant both minter
* and pauser roles to other accounts.
*/
contract assignmentERC20PresetMinterPauser is Context, AccessControl, ERC20Burnable, ERC20Pausable {
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant SETCAP_ROLE = keccak256("SETCAP_ROLE");
uint256 private _cap;
/**
* @dev Grants `DEFAULT_ADMIN_ROLE`, `MINTER_ROLE` and `PAUSER_ROLE` and `SETCAP_ROLE` to the
* account that deploys the contract.
*
* Sets cap on number of tokens
*
* See {ERC20-constructor}.
*/
constructor (string memory name, string memory symbol, uint cap_) public ERC20(name, symbol) {
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(SETCAP_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
}
/**
* @dev Returns the cap on the token's total supply.
*/
function cap() public view virtual returns (uint256) {
return _cap;
}
/**
* @dev Sets new cap limit.
*
*
*
* Requirements:
*
* - the caller must have the `SETCAP_ROLE`.
*/
function setCap(uint256 setNewCap) public virtual returns (uint256) {
require(hasRole(SETCAP_ROLE, _msgSender()), "assignmentERC20PresetMinterPauser: must have setcap role to set cap");
require(setNewCap >= _totalSupply, "assignmentERC20PresetMinterPauser: Cap is less than total supply");
require(setNewCap > 0, "assignmentERC20PresetMinterPauser: New cap cannot be 0");
_cap = setNewCap;
return _cap;
}
/**
* @dev Creates `amount` new tokens for `to`.
*
* See {ERC20-_mint}.
*
* Requirements:
*
* - the caller must have the `MINTER_ROLE`.
*/
function mint(address to, uint256 amount) public virtual {
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
/**
* @dev Pauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_pause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
/**
* @dev Unpauses all token transfers.
*
* See {ERC20Pausable} and {Pausable-_unpause}.
*
* Requirements:
*
* - the caller must have the `PAUSER_ROLE`.
*/
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
/**
* @dev See {ERC20-_beforeTokenTransfer}.
*
* Requirements:
*
* - minted tokens must not cause the total supply to go over the cap.
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) { // When minting tokens
require(totalSupply().add(amount) <= cap(), "ERC20Capped: cap exceeded");
}
}
}
Ben
1 Like
okay so this is the code, it seems that its the same as everyone elses, but then i keep trying to deploy this :
constructor(string memory name, string memory symbol, uint cap) ERC20(name, symbol)
and it shows an error saying : āERC20PresetMinterPauserā ā Invalid number of parameters for āundefinedā. Got 0 expected 2!
And then if i try to compile this :
constructor(string memory name, string memory symbol) ERC20("mytoken", "mtkn")
i still get the same error, can anyone explain to me how do i deploy these? im pretty sure this has a simple solution, but truth is i am not really familiar with truffle or constructors, so every little thing i try gives me an error -.-, anyways im gonna go ahead and watch filips video, maybe he deploys his contract in the video xD, heres my code :
Summary
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
import "../node_modules/@openzeppelin/contracts/token/ERC20/extensions/ERC20Pausable.sol";
import "../node_modules/@openzeppelin/contracts/access/AccessControlEnumerable.sol";
import "../node_modules/@openzeppelin/contracts/utils/Context.sol";
contract ERC20PresetMinterPauser is Context, AccessControlEnumerable, ERC20Burnable, ERC20Pausable {
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
bytes32 public constant CAPSETTER_ROLE = keccak256("CAPSETTER_ROLE");
uint256 private _cap;
constructor(string memory name, string memory symbol) ERC20(name, symbol) {
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, _msgSender());
_setupRole(PAUSER_ROLE, _msgSender());
_setupRole(CAPSETTER_ROLE, _msgSender());
setCap(100000);
}
function setCap(uint256 cap_) internal virtual {
require(hasRole(CAPSETTER_ROLE, _msgSender()), "must have Capsetter role to set cap");
require(cap_ > 0, "ERC20Capped: cap is 0");
_cap = cap_;
}
function mint(address to, uint256 amount) public virtual {
require(ERC20.totalSupply() + amount <= _cap, "Cap exceeded");
require(hasRole(MINTER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have minter role to mint");
_mint(to, amount);
}
function pause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to pause");
_pause();
}
function unpause() public virtual {
require(hasRole(PAUSER_ROLE, _msgSender()), "ERC20PresetMinterPauser: must have pauser role to unpause");
_unpause();
}
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual override(ERC20, ERC20Pausable) {
super._beforeTokenTransfer(from, to, amount);
}
}
If anyone has a clue about what my issue is, ill be glad to hear it xD
Hey @Carlosvh96
I need to see your migration file in order to help you.
Truffle is telling you that your contract constructor requires two params, but you are sending 0.
You should send params to your constructor when deploying the contract.
Regards,
Dani
Heres my migration file, and about the parameters, i know it says so, but thats exactly what im asking, i thought that the parameters where name and symbol, so thats why i keep changing those 
Summary
const ERC20PresetMinterPauser = artifacts.require("ERC20PresetMinterPauser");
module.exports = function (deployer) {
deployer.deploy(ERC20PresetMinterPauser);
};
is this the file that you need @dan-i ? or which one?