Step 6 - Functions

Author: zeeshanhanif

06_functions_2/README.md

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+# Functions

06_functions_2/contracts/Contract1.sol

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+pragma solidity ^0.4.23;
+contract Contract1 {
+
+    int public age;
+    
+    function setAge(int a) public constant {
+        // Changing state variable in constant function is not allowed
+        // This will raise warning but no error, this is not
+        // strictly enforced yet
+        age = a;
+    }
+
+    
+    function doSomeWork() public constant returns (int) {
+        // No warning or error works fine
+        // Accessing state variable in local and returning from
+        // function 
+        int b = age;
+        return b;
+    }
+
+    
+    function doSomeWork2() public constant returns (int) {
+        // No warning or error works fine
+        // Returning state variable from function 
+        return age;
+    }
+
+    function doSomeWork3() public view returns (int) {
+        // Not allowed to change state variables, but shows only warning 
+        age = 10;
+        return age;
+    }
+
+    // pure function 
+    function doSomeWork4(int b) public pure returns (int) {
+        // Compilation error, on both changing state variable or access
+        // state variable
+
+        // access or assignment not allowed
+        //age = b;  // not allowed, uncoment and try
+        //b = age;  // not allowed, uncoment and try
+        return b;
+    }
+
+    // Returning multiple values from function
+    function doSomeWork6(int c) public returns (int,string) {
+        return (5,"hello");
+    }
+
+}

06_functions_2/contracts/Migrations.sol

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+pragma solidity ^0.4.23;
+
+contract Migrations {
+  address public owner;
+  uint public last_completed_migration;
+
+
+  constructor() public {
+    owner = msg.sender;
+  }
+
+  modifier restricted() {
+    if (msg.sender == owner) _;
+  }
+
+  function setCompleted(uint completed) public restricted {
+    last_completed_migration = completed;
+  }
+
+  function upgrade(address new_address) public restricted {
+    Migrations upgraded = Migrations(new_address);
+    upgraded.setCompleted(last_completed_migration);
+  }
+}

06_functions_2/migrations/1_initial_migration.js

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+var Migrations = artifacts.require("./Migrations.sol");
+
+module.exports = function(deployer) {
+  deployer.deploy(Migrations);
+};

06_functions_2/migrations/2_custom.js

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+var contract1 = artifacts.require("./Contract1.sol");
+
+module.exports = function(deployer) {
+  deployer.deploy(contract1);
+};

06_functions_2/test/TestContract1.sol

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+pragma solidity ^0.4.19;
+import "truffle/Assert.sol";
+import "truffle/DeployedAddresses.sol";
+import "../contracts/Contract1.sol";
+
+contract TestContract1 {
+
+    function testConstantFunction() public { 
+        Contract1 meta = Contract1(DeployedAddresses.Contract1());
+        meta.setAge(5);
+    }
+
+    function testConstantFunction2() public { 
+        Contract1 meta = Contract1(DeployedAddresses.Contract1());
+        
+        Assert.equal(meta.doSomeWork(),5,"Testing constant function, value should be 5");
+        Assert.equal(meta.doSomeWork2(),5,"Testing constant function, value should be 5");
+    }
+
+    function testViewFunction() public { 
+        Contract1 meta = Contract1(DeployedAddresses.Contract1());
+        
+        Assert.equal(meta.doSomeWork3(),10,"Testing view function, value should be 5");
+    }
+
+    function testPureFunction() public { 
+        Contract1 meta = Contract1(DeployedAddresses.Contract1());
+        
+        Assert.equal(meta.doSomeWork4(3),3,"Testing pure function, value should be 5");
+    }
+
+    function testMultipleReturnFunction() public { 
+        Contract1 meta = Contract1(DeployedAddresses.Contract1());
+        // both of the below lines will work
+        //var (a, b) = meta.doSomeWork6(3);
+        //(int a, int b) = (5,6);
+        (int a, string memory b)= meta.doSomeWork6(3);
+        Assert.equal(a,5,"Testing multiple return funciton, A should be 5");
+        Assert.equal(b,"hello","Testing multiple return funciton, B should be hello");
+    }
+}

06_functions_2/truffle-config.js

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+module.exports = {
+  // See <http://truffleframework.com/docs/advanced/configuration>
+  // to customize your Truffle configuration!
+};

06_functions_2/truffle.js

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+module.exports = {
+  // See <http://truffleframework.com/docs/advanced/configuration>
+  // to customize your Truffle configuration!
+  networks: {
+    development: {
+      host: "127.0.0.1",
+      port: 8545,
+      network_id: "*" // Match any network id
+    }
+  }
+};