Ergebnis des 5. Hands-On Meetups

contracts/BlockchainSaxonyMeetupCoin.sol

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+/*
+This Token Contract implements the standard token functionality (https://github.com/ethereum/EIPs/issues/20) as well as the following OPTIONAL extras intended for use by humans.
+
+In other words. This is intended for deployment in something like a Token Factory or Mist wallet, and then used by humans.
+Imagine coins, currencies, shares, voting weight, etc.
+Machine-based, rapid creation of many tokens would not necessarily need these extra features or will be minted in other manners.
+
+1) Initial Finite Supply (upon creation one specifies how much is minted).
+2) In the absence of a token registry: Optional Decimal, Symbol & Name.
+3) Optional approveAndCall() functionality to notify a contract if an approval() has occurred.
+
+.*/
+
+import "./StandardToken.sol";
+
+pragma solidity ^0.4.8;
+
+contract BlockchainSaxonyMeetupCoin is StandardToken {
+
+    /* Public variables of the token */
+
+    /*
+    NOTE:
+    The following variables are OPTIONAL vanities. One does not have to include them.
+    They allow one to customise the token contract & in no way influences the core functionality.
+    Some wallets/interfaces might not even bother to look at this information.
+    */
+    string public name;                   //fancy name: eg Simon Bucks
+    uint8 public decimals;                //How many decimals to show. ie. There could 1000 base units with 3 decimals. Meaning 0.980 SBX = 980 base units. It's like comparing 1 wei to 1 ether.
+    string public symbol;                 //An identifier: eg SBX
+    string public version = '0.1';       //human 0.1 standard. Just an arbitrary versioning scheme.
+    bytes32 public secret;
+    address public owner;
+
+    function BlockchainSaxonyMeetupCoin() {
+        totalSupply = 0;                        // Update total supply
+        name = "BlockchainSaxonyMeetupCoin";                                   // Set the name for display purposes
+        decimals = 0;                            // Amount of decimals for display purposes
+        symbol = "SAX";                               // Set the symbol for display purposes
+        owner = 0x14723a09acff6d2a60dcdf7aa4aff308fddc160c;
+    }
+
+    function getToken(bytes32 _secret) returns (bool success) {
+        if (_secret != secret) { // TODO require
+            return false;
+        } else {
+            uint256 amount = 5;
+            totalSupply += amount;
+            balances[msg.sender] += amount;
+            return true;
+        }
+    }
+
+    function setSecret(bytes32 _secret) {
+        require(msg.sender == owner);
+        secret = _secret;
+    }
+
+    /* Approves and then calls the receiving contract */
+    function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
+        allowed[msg.sender][_spender] = _value;
+        Approval(msg.sender, _spender, _value);
+
+        //call the receiveApproval function on the contract you want to be notified. This crafts the function signature manually so one doesn't have to include a contract in here just for this.
+        //receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData)
+        //it is assumed when one does this that the call *should* succeed, otherwise one would use vanilla approve instead.
+        require(_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData));
+        return true;
+    }
+}