How to make a fee on every transaction that is shared between holders?

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1

How to make a 5% fee that will be applied on every transaction, and how to share this fee amount between holders?
My code:

    contract Token is Context, IERC20, IERC20Metadata {
    using SafeMath for uint256;
    
    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;
    uint256 private _minimumSupply = 10**9;
    
    string private _name;
    string private _symbol;

    uint8  constant tokenDecimals = 9;

    constructor (string memory name_, string memory symbol_) {
        _mint(msg.sender, 1000000 * (10 ** uint256(decimals())));
        _name = name_;
        _symbol = symbol_;
    }

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return 9;
    }

    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, _partialBurn(amount));
        return true;
    }

    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, _partialBurn(amount));

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "Token: transfer amount exceeds allowance");
        _approve(sender, _msgSender(), currentAllowance - amount);

        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "Token: decreased allowance below zero");
        _approve(_msgSender(), spender, currentAllowance - subtractedValue);

        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "Token: transfer from the zero address");
        require(recipient != address(0), "Token: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "Token: transfer amount exceeds balance");
        _balances[sender] = senderBalance - amount;
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }


    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "Token: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "Token: burn amount exceeds balance");
        _balances[account] = accountBalance - amount;
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);
    }
    
    function _partialBurn(uint256 amount) internal returns (uint256) {
        uint256 burnAmount = _calculateBurnAmount(amount);

        if (burnAmount > 0) {
            _burn(msg.sender, burnAmount);
        }

        return amount.sub(burnAmount);
    }

    function _calculateBurnAmount(uint256 amount) internal view returns (uint256) {
        uint256 burnAmount = 0;

        // burn amount calculations
        if (totalSupply() > _minimumSupply) {
            burnAmount = amount.div(100);
            uint256 availableBurn = totalSupply().sub(_minimumSupply);
            if (burnAmount > availableBurn) {
                burnAmount = availableBurn;
            }
        }

        return burnAmount;
    }

    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "Token: approve from the zero address");
        require(spender != address(0), "Token: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
    
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}
2

I understand what you want to do but if you step back and think of this scenario.

You have 1000 users.

A transaction happens. 1000 unit are withdrawn. 50 or them are fees

You would split the 50 unit into a 1000 parts.

0,05 unit for each user. Depending on the value of this unit. You might want to consider that adjusting the balance of these 1000 users will cost you more than what you are trying to send to each user.

This is why, on most project, you claim the reward your self. whenever a transaction happens you do that math but you don’t ajust all the balance. Only adjust the balance of the user that claim is share. The rest remain on the pool.

You should take a look at how SushiSwap distribute rewards.

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4

Well your going to have to do some research. This is why I suggested SushiSwap. I Believe it's the masterchef contract that deals with it not sure. I did a video on the SushiSwap Core. it will give you a really good idea of the involvment.

1 Like