Home / Crypto Currency Video / Ethereum Core Devs Meeting #33 [02/09/18]

Ethereum Core Devs Meeting #33 [02/09/18]



Agenda: https://github.com/ethereum/pm/issues/31

About admin

Check Also

Alt Coins Price Analysis March 28, 2018 by FXEmpire.com

The alt cash fell all the way through the buying and selling consultation on Monday, …

7 comments

  1. Thanks devs

  2. someone should log topics and timestamps ( not me ;)….)

  3. Awesome! Also, I need that intro as my live wallpaper.

  4. hello ethereum developers
    I need your help
    I tried to create contract using your example codes
    here this codes

    pragma solidity ^0.4.16;

    contract owned {
    address public owner;

    function owned() public {
    owner = msg.sender;
    }

    modifier onlyOwner {
    require(msg.sender == owner);
    _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
    owner = newOwner;
    }
    }

    interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

    contract TokenERC20 {
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 18;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);

    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);

    /**
    * Constrctor function
    *
    * Initializes contract with initial supply tokens to the creator of the contract
    */
    function TokenERC20(
    uint256 initialSupply,
    string tokenName,
    string tokenSymbol
    ) public {
    totalSupply = initialSupply * 10 ** uint256(decimals); // Update total supply with the decimal amount
    balanceOf[msg.sender] = totalSupply; // Give the creator all initial tokens
    name = tokenName; // Set the name for display purposes
    symbol = tokenSymbol; // Set the symbol for display purposes
    }

    /**
    * Internal transfer, only can be called by this contract
    */
    function _transfer(address _from, address _to, uint _value) internal {
    // Prevent transfer to 0x0 address. Use burn() instead
    require(_to != 0x0);
    // Check if the sender has enough
    require(balanceOf[_from] >= _value);
    // Check for overflows
    require(balanceOf[_to] + _value > balanceOf[_to]);
    // Save this for an assertion in the future
    uint previousBalances = balanceOf[_from] + balanceOf[_to];
    // Subtract from the sender
    balanceOf[_from] -= _value;
    // Add the same to the recipient
    balanceOf[_to] += _value;
    Transfer(_from, _to, _value);
    // Asserts are used to use static analysis to find bugs in your code. They should never fail
    assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    /**
    * Transfer tokens
    *
    * Send `_value` tokens to `_to` from your account
    *
    * @param _to The address of the recipient
    * @param _value the amount to send
    */
    function transfer(address _to, uint256 _value) public {
    _transfer(msg.sender, _to, _value);
    }

    /**
    * Transfer tokens from other address
    *
    * Send `_value` tokens to `_to` in behalf of `_from`
    *
    * @param _from The address of the sender
    * @param _to The address of the recipient
    * @param _value the amount to send
    */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
    require(_value <= allowance[_from][msg.sender]); // Check allowance
    allowance[_from][msg.sender] -= _value;
    _transfer(_from, _to, _value);
    return true;
    }

    /**
    * Set allowance for other address
    *
    * Allows `_spender` to spend no more than `_value` tokens in your behalf
    *
    * @param _spender The address authorized to spend
    * @param _value the max amount they can spend
    */
    function approve(address _spender, uint256 _value) public
    returns (bool success) {
    allowance[msg.sender][_spender] = _value;
    return true;
    }

    /**
    * Set allowance for other address and notify
    *
    * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
    *
    * @param _spender The address authorized to spend
    * @param _value the max amount they can spend
    * @param _extraData some extra information to send to the approved contract
    */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData)
    public
    returns (bool success) {
    tokenRecipient spender = tokenRecipient(_spender);
    if (approve(_spender, _value)) {
    spender.receiveApproval(msg.sender, _value, this, _extraData);
    return true;
    }
    }

    /**
    * Destroy tokens
    *
    * Remove `_value` tokens from the system irreversibly
    *
    * @param _value the amount of money to burn
    */
    function burn(uint256 _value) public returns (bool success) {
    require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
    balanceOf[msg.sender] -= _value; // Subtract from the sender
    totalSupply -= _value; // Updates totalSupply
    Burn(msg.sender, _value);
    return true;
    }

    /**
    * Destroy tokens from other account
    *
    * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
    *
    * @param _from the address of the sender
    * @param _value the amount of money to burn
    */
    function burnFrom(address _from, uint256 _value) public returns (bool success) {
    require(balanceOf[_from] >= _value); // Check if the targeted balance is enough
    require(_value <= allowance[_from][msg.sender]); // Check allowance
    balanceOf[_from] -= _value; // Subtract from the targeted balance
    allowance[_from][msg.sender] -= _value; // Subtract from the sender's allowance
    totalSupply -= _value; // Update totalSupply
    Burn(_from, _value);
    return true;
    }
    }

    /******************************************/
    /* ADVANCED TOKEN STARTS HERE */
    /******************************************/

    contract MyAdvancedToken is owned, TokenERC20 {

    uint256 public sellPrice;
    uint256 public buyPrice;

    mapping (address => bool) public frozenAccount;

    /* This generates a public event on the blockchain that will notify clients */
    event FrozenFunds(address target, bool frozen);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    function MyAdvancedToken(
    uint256 initialSupply,
    string tokenName,
    string tokenSymbol
    ) TokenERC20(initialSupply, tokenName, tokenSymbol) public {}

    /* Internal transfer, only can be called by this contract */
    function _transfer(address _from, address _to, uint _value) internal {
    require (_to != 0x0); // Prevent transfer to 0x0 address. Use burn() instead
    require (balanceOf[_from] >= _value); // Check if the sender has enough
    require (balanceOf[_to] + _value > balanceOf[_to]); // Check for overflows
    require(!frozenAccount[_from]); // Check if sender is frozen
    require(!frozenAccount[_to]); // Check if recipient is frozen
    balanceOf[_from] -= _value; // Subtract from the sender
    balanceOf[_to] += _value; // Add the same to the recipient
    Transfer(_from, _to, _value);
    }

    /// @notice Create `mintedAmount` tokens and send it to `target`
    /// @param target Address to receive the tokens
    /// @param mintedAmount the amount of tokens it will receive
    function mintToken(address target, uint256 mintedAmount) onlyOwner public {
    balanceOf[target] += mintedAmount;
    totalSupply += mintedAmount;
    Transfer(0, this, mintedAmount);
    Transfer(this, target, mintedAmount);
    }

    /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
    /// @param target Address to be frozen
    /// @param freeze either to freeze it or not
    function freezeAccount(address target, bool freeze) onlyOwner public {
    frozenAccount[target] = freeze;
    FrozenFunds(target, freeze);
    }

    /// @notice Allow users to buy tokens for `newBuyPrice` eth and sell tokens for `newSellPrice` eth
    /// @param newSellPrice Price the users can sell to the contract
    /// @param newBuyPrice Price users can buy from the contract
    function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner public {
    sellPrice = newSellPrice;
    buyPrice = newBuyPrice;
    }

    /// @notice Buy tokens from contract by sending ether
    function buy() payable public {
    uint amount = msg.value / buyPrice; // calculates the amount
    _transfer(this, msg.sender, amount); // makes the transfers
    }

    /// @notice Sell `amount` tokens to contract
    /// @param amount amount of tokens to be sold
    function sell(uint256 amount) public {
    require(this.balance >= amount * sellPrice); // checks if the contract has enough ether to buy
    _transfer(msg.sender, this, amount); // makes the transfers
    msg.sender.transfer(amount * sellPrice); // sends ether to the seller. It's important to do this last to avoid recursion attacks
    }
    }
    when I complie it show error in function TokenERC20(
    uint256 initialSupply,
    string tokenName,
    string tokenSymbol)
    so I deleted within() this codes – uint256 initialSupply,
    string tokenName,
    string tokenSymbol
    but more error occurs in advanced tokens here

  5. My only comment is please balance the volumes of each user. My ears hurt when swapping between certain devs.

  6. Need info on the carbon footprint of ETH currently, and any less energy intensive future release planed

Leave a Reply

Your email address will not be published. Required fields are marked *