ERC-20
This standard provides basic functionality to transfer tokens, as well as allow tokens to be approved so they can be spent by another on-chain third party.
https://eips.ethereum.org/EIPS/eip-20
📄️ Approve Pattern
Based on ERC20 token learn the rules for transfering tokens, including the approval pattern when a user wishes to instruct a vendor contract to sell a proportion of their tokens.
Functions
| Function | Notes |
|---|---|
| totalSupply() | |
| balanceOf(account) | |
| allowance(owner, spender) | |
| approve(spender, amount) | |
| transfer(to, amount) | |
| transferFrom(from, to, amount) |
Transfer
Some ERC20 contracts were created before the EIP-20 standard was published correctly. Therefore it is necessary to take extra precautions to confirm that a transfer to another ERC20 contract is valid.
It is necessary to take extra precautions to confirm that a transfer to another ERC20 contract is valid.
function _safeTransfer(address token, address to, uint value) private {
(bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
}
Events
Transfer(from, to, value)
Approval(owner, spender, value)
Checklists
Use these checklists to confirm best practices have been followed and no security issues exist.