会见节制是软件基本设施安详的根基要素。企业应用措施需要严格的法则来抉择谁可以做什么，这取决于每个用户的权限。可以说，智能合约中的会见节制需要更严格的审查，因为裂痕大概导致恶意参加者节制系统。
这些当前的办理方案在陈设智能合约之前提供了脚色的机动性。由于脚色取决于硬编码法则，因此不支持动态建设的脚色。这很是适合在已知的内部智能合约之间提供会见节制，但它不能提供与现代面向用户的会见节制软件相当的机动性。
152 * - the caller must be `account`.
17
100 * @dev Returns the admin role that controls `role`. See {grantRole} and
42 struct RoleData {
25 * ...
112 * If `account` had not been already granted `role`, emits a {RoleGranted}
15 public
Limitations（范围性)
1pragma solidity ^0.6.0;
36}

7 * specific functions.
4

56 function renounceOwnership() public onlyOwner {
87 * Role bearers are not sorted in any particular way, and their ordering may
102 *
45 }
35 * @dev Throws if called by any account other than the owner.
3/**
43 EnumerableSet.AddressSet members;
32 function has(Role storage role, address account) internal view returns (bool) {
4import "../utils/Address.sol";
54 * thereby removing any functionality that is only available to the owner.
55 * bearer except when using {_setupRole}.
18 }
61 *
46
158 }
132 * - the caller must have ``role``'s admin role.
153 */
143 * Roles are often managed via {grantRole} and {revokeRole}: this function's
3import "../GSN/Context.sol";
在runtime，Ownable或Roles都不满意这些民众模式中的任何一种。假如需要建设新脚色，则需要发送新代码。这些体系布局不答允InfoSec打点员通过简朴的界面建设、更新或删除新脚色。
20 * function call, use {hasRole}:
38 require(isOwner(), "Ownable: caller is not the owner");
59 }
10 * `onlyOwner`, which can be applied to your functions to restrict their use to
161 * @dev Grants `role` to `account`.
9 * control mechanisms.
121
代码1显示了Ownable智能合约的Openzeppelin实现。
只要系统不需要新的脚色，RBAC主要通过Roles智能合约来满意。
8 using Roles for Roles.Role;
71 */
36
9
2
62 * `sender` is the account that originated the contract call:
171 function _setupRole(bytes32 role, address account) internal virtual {
52 * @dev Emitted when `account` is granted `role`.
147 * If the calling account had been granted `role`, emits a {RoleRevoked}
24 require(has(role, account), "Roles: account does not have role");

77 * together with {getRoleMember} to enumerate all bearers of a role.
25
40 using Address for address;
127 *
35 require(_burners.has(msg.sender), "DOES_NOT_HAVE_BURNER_ROLE");
31 */
留意：不发起您在出产应用措施中利用此办理方案，因为它仍处于测试阶段。
33 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
11 * the owner.
136
7contract MyToken is ERC20, ERC20Detailed {
165 * checks on the calling account.
110 * @dev Grants `role` to `account`.
12 }
125 /**
166 *
21 constructor () internal {
156
168 *
129 *
108
64 */
Access Control (Beta)
尽量这为大大都智能合约应用措施提供了精采的基本，但基于现有的脚色的会见节制（RBAC）系统使打点员可以或许在运行时动态地界说脚色。从这个意义上说，Roles智能合约是具有限制性的，因为在陈设之后无法界说脚色。
2

12 */
81 }
24 * require(hasRole(MY_ROLE, _msgSender()));
34 * that only accounts with this role will be able to grant or revoke other
80 return _roles[role].members.length();
22 _burners.add(burners[i]);
107 }
113 * event.
24 emit OwnershipTransferred(address(0), msgSender);
176 /**
20 /**
142 *
Roles
52 *
38 }
46 return _msgSender() == _owner;
111 *
115 * Requirements:
92 * https://forum.openzeppelin.com/t/iterating-over-el... post]
68
169 * - this function can only be called from a constructor.
154 function renounceRole(bytes32 role, address account) public virtual {
它具有机动性，答允智能合约界说所需的尽大概多的脚色，，但这将require语句的实现留给了智能合约。由于未提供自界说会见修饰符，因此在某种水平上低落了可读性，而且增加了引入编码错误的大概性。可是没有什么能阻止智能合约实现包括require语句的自界说会见修饰符。
34 return role.bearer[account];
13}
95 function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
16 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
16 event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
78 */
16 require(!has(role, account), "Roles: account already has role");
159
114 *
代码5展示了AccessControl的实现。
70 * @dev Transfers ownership of the contract to a new account (`newOwner`).
70 */
155 require(account == _msgSender(), "AccessControl: can only renounce roles for self");
代码3展示了Roles智能合约的实施。与Ownable差异，Role不提供自界说会见修饰符。相反利用此库的智能合约必需在函数内部实现脚色要求。他们还必需为每个脚色界说Roles.Role范例状态变量。代码4展示了实现两个脚色的ERC20智能合约的示例：_burners和_minters。
58 _owner = address(0);

50 * @dev Leaves the contract without owner. It will not be possible to call
22 */
62 * @dev Transfers ownership of the contract to a new account (`newOwner`).

44 */
55 */
77}
96 return _roles[role].members.at(index);
36 * {_setRoleAdmin}.
45 function isOwner() public view returns (bool) {
61 /**
3import "../utils/EnumerableSet.sol";
27 * ```
23 * function foo() public {
幸运的是，我们正在尽力办理这一问题。
28 *
144 * purpose is to provide a mechanism for accounts to lose their privileges
146 *
10 }
1pragma solidity ^0.5.0;
26 * }
32 *
在RBAC中，每个用户都被分派了一个脚色，每个脚色都具有一组权限，而且只要他们的脚色具有正确的权限，用户就可以会见资源。
9 mapping (address => bool) bearer;
18 *
65 */
21 *
138 }
2
73 }
64 * - if using `renounceRole`, it is the role bearer (i.e. `account`)
94 */
181 }
Only Owner
8 *
74 emit OwnershipTransferred(_owner, newOwner);
13 constructor(address[] memory minters, address[] memory burners)
22 address msgSender = _msgSender();
44 bytes32 adminRole;
25 }
16 {
39}
1pragma solidity ^0.5.0;

24 }
与RBAC对比，这是一个更巨大且耗时的办理方案。可是对付大型应用措施和企业而言，它越发机动，因为它答允每个用户独占的各类权限。
28 /**
150 * Requirements:
179 function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
19 * Roles can be used to represent a set of permissions. To restrict access to a
48
27
75 /**
35 * roles. More complex role relationships can be created by using
41
178 */
116 *
69 /**
6
5import "../GSN/Context.sol";
79 function getRoleMemberCount(bytes32 role) public view returns (uint256) {
98
174 }
8 * @dev Contract module that allows children to implement role-based access
163 * If `account` had not been already granted `role`, emits a {RoleGranted}
在ABAC中，为每个用户分派了一组主题属性，为每个资源分派了一组工具属性。中央会见节制机构界说有关需要执行哪些主题和工具属性的法则。
25 role.bearer[account] = false;
38abstract contract AccessControl is Context {
73 require(newOwner != address(0), "Ownable: new owner is the zero address");
13contract Ownable is Context {
28 require(_minters.has(msg.sender), "DOES_NOT_HAVE_MINTER_ROLE");
4/**

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