10-姚子豪-第四课作业

Lesson-2/README.md

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+## 硅谷live以太坊智能合约频道官方地址
+
+### 第二课《智能合约设计进阶-多员工薪酬系统》
+
+目录结构
+  <br/>|
+  <br/>|--orgin 课程初始代码
+  <br/>|
+  <br/>|--assignment 课程作业提交代码
+<br/> 
+### 本节知识点
+第2课：智能合约设计进阶-多员工薪酬系统
+- 动态静态数组的不同
+- 函数输入参数检查 revert
+- 循环与遍历的安全性
+- 程序运行错误检查和容错：assert与require

Lesson-2/assignment/README.md

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+## 硅谷live以太坊智能合约 第二课作业
+这里是同学提交作业的目录
+
+### 第二课：课后作业
+完成今天的智能合约添加100ETH到合约中
+- 加入十个员工，每个员工的薪水都是1ETH
+每次加入一个员工后调用calculateRunway这个函数，并且记录消耗的gas是多少？Gas变化么？如果有 为什么？
+- 如何优化calculateRunway这个函数来减少gas的消耗？
+提交：智能合约代码，gas变化的记录，calculateRunway函数的优化
+

Lesson-2/assignment/yours.sol

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+/*作业请提交在这个目录下*/

Lesson-2/orgin/README.md

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+## 硅谷live以太坊智能合约 第二课《智能合约设计进阶-多员工薪酬系统》
+
+这里是每一课的初始代码，有需要的同学可以参考

Lesson-2/orgin/payroll.sol

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+pragma solidity ^0.4.14;
+
+contract Payroll {
+    struct Employee {
+        address id;
+        uint salary;
+        uint lastPayday;
+    }
+
+    uint constant payDuration = 10 seconds;
+
+    address owner;
+    Employee[] employees;
+
+    function Payroll() {
+        owner = msg.sender;
+    }
+
+    function _partialPaid(Employee employee) private {
+    }
+
+    function _findEmployee(address employeeId) private returns (Employee, uint) {
+    }
+
+    function addEmployee(address employeeId, uint salary) {
+    }
+
+    function removeEmployee(address employeeId) {
+    }
+
+    function updateEmployee(address employeeId, uint salary) {
+    }
+
+    function addFund() payable returns (uint) {
+    }
+
+    function calculateRunway() returns (uint) {
+        uint totalSalary = 0;
+       for (uint i = 0; i < employees.length; i++) {
+            totalSalary += employees[i].salary;
+        }
+        return this.balance / totalSalary;
+    }
+
+    function hasEnoughFund() returns (bool) {
+    }
+
+    function getPaid() {
+    }
+}

Lesson-3/README.md

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+## 硅谷live以太坊智能合约频道官方地址
+
+### 第三课《智能合约后端优化和产品化》
+
+目录结构
+  <br/>|
+  <br/>|--orgin 课程初始代码
+  <br/>|
+  <br/>|--assignment 课程作业提交代码
+<br/> 
+### 本节知识点
+第3课：智能合约后端优化和产品化
+- 如何通过数据结构优化降低合约执行成本
+- 合约的继承
+- 巧用modifier
+- 以太坊函数库的使用和基本介绍

Lesson-3/assignment/README.md

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+## 硅谷live以太坊智能合约 第三课作业
+这里是同学提交作业的目录
+
+### 第三课：课后作业
+- 第一题：完成今天所开发的合约产品化内容，使用Remix调用每一个函数，提交函数调用截图
+- 第二题：增加 changePaymentAddress 函数，更改员工的薪水支付地址，思考一下能否使用modifier整合某个功能
+- 第三题（加分题）：自学C3 Linearization, 求以下 contract Z 的继承线
+- contract O
+- contract A is O
+- contract B is O
+- contract C is O
+- contract K1 is A, B
+- contract K2 is A, C
+- contract Z is K1, K2

Lesson-3/assignment/yours.sol

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+/*作业请提交在这个目录下*/

Lesson-3/orgin/README.md

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+## 硅谷live以太坊智能合约 第三课
+
+这里是每一课的初始代码，有需要的同学可以参考

Lesson-4/README.md

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+## 硅谷live以太坊智能合约频道官方地址
+
+### 第四课《使用Truffle架构进行前后端交互，测试，部署》
+
+目录结构
+  <br/>|
+  <br/>|--orgin 课程初始代码
+  <br/>|
+  <br/>|--assignment 课程作业提交代码
+<br/> 
+### 本节知识点
+第4课：使用Truffle架构进行前后端交互，测试，部署
+- 为什么要用Truffle，Truffle的基本概念
+- Truffle 的command line 功能
+- 初始化项目与Truffle项目目录结构
+- 编译部署合约到testrpc

Lesson-4/assignment/Ownable.sol

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+pragma solidity ^0.4.18;
+
+
+/**
+ * @title Ownable
+ * @dev The Ownable contract has an owner address, and provides basic authorization control
+ * functions, this simplifies the implementation of "user permissions".
+ */
+contract Ownable {
+  address public owner;
+
+
+  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
+
+
+  /**
+   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
+   * account.
+   */
+  function Ownable() public {
+    owner = msg.sender;
+  }
+
+  /**
+   * @dev Throws if called by any account other than the owner.
+   */
+  modifier onlyOwner() {
+    require(msg.sender == owner);
+    _;
+  }
+
+  /**
+   * @dev Allows the current owner to transfer control of the contract to a newOwner.
+   * @param newOwner The address to transfer ownership to.
+   */
+  function transferOwnership(address newOwner) public onlyOwner {
+    require(newOwner != address(0));
+    OwnershipTransferred(owner, newOwner);
+    owner = newOwner;
+  }
+
+}

Lesson-4/assignment/PullPayment.sol

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+pragma solidity ^0.4.18;
+
+
+import "./SafeMath.sol";
+
+
+/**
+ * @title PullPayment
+ * @dev Base contract supporting async send for pull payments. Inherit from this
+ * contract and use asyncSend instead of send.
+ */
+contract PullPayment {
+  using SafeMath for uint256;
+
+  mapping(address => uint256) public payments;
+  uint256 public totalPayments;
+
+  /**
+  * @dev withdraw accumulated balance, called by payee.
+  */
+  function withdrawPayments() public {
+    address payee = msg.sender;
+    uint256 payment = payments[payee];
+
+    require(payment != 0);
+    require(this.balance >= payment);
+
+    totalPayments = totalPayments.sub(payment);
+    payments[payee] = 0;
+
+    assert(payee.send(payment));
+  }
+
+  /**
+  * @dev Called by the payer to store the sent amount as credit to be pulled.
+  * @param dest The destination address of the funds.
+  * @param amount The amount to transfer.
+  */
+  function asyncSend(address dest, uint256 amount) internal {
+    payments[dest] = payments[dest].add(amount);
+    totalPayments = totalPayments.add(amount);
+  }
+}

Lesson-4/assignment/README.md

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+## 硅谷live以太坊智能合约 第四课作业
+这里是同学提交作业的目录
+
+### 第四课：课后作业
+- 将第三课完成的payroll.sol程序导入truffle工程
+- 在test文件夹中，写出对如下两个函数的单元测试：
+- function addEmployee(address employeeId, uint salary) onlyOwner
+- function removeEmployee(address employeeId) onlyOwner employeeExist(employeeId)
+- 思考一下我们如何能覆盖所有的测试路径，包括函数异常的捕捉
+- (加分题,选作）
+- 写出对以下函数的基于solidity或javascript的单元测试 function getPaid() employeeExist(msg.sender)
+- Hint：思考如何对timestamp进行修改，是否需要对所测试的合约进行修改来达到测试的目的？

Lesson-4/assignment/SafeMath.sol

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+pragma solidity ^0.4.18;
+
+
+/**
+ * @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) {
+    if (a == 0) {
+      return 0;
+    }
+    uint256 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 c;
+  }
+
+  /**
+  * @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) {
+    uint256 c = a + b;
+    assert(c >= a);
+    return c;
+  }
+}