The basic standard API for tokens, on EOSio networks, does not allow practical implementations of non-custodian peer-to-peer applications. The following smart contract, closely inspired by the ERC-20 Ethereum standard, allows users to preapprove other accounts (or smart contracts) to spend a designated amount of funds in their name. To do so, we have implemented two new actions that are added to the standard eosio.token contract:
- approve: Give spending privileges to another account
- transferfrom: Spend funds in the name of another account which preapproved the spender
On the Ethereum platform, tokens are implemented as ledgers with a Solidity smart contract. One token/ledger per contract. These ERC20 ledgers are set as two-column tables comprising user accounts and account balances (see left illustration below) and stored in the scope of the contract. Hence, to query all of a user's account balances, we need a list of all ERC20 contract addresses of the relevant tokens.
In contrast, in EOSio networks the standard eosio.token contract allows the creation of many tokens. The ledgers are set in a two-column table comprising tokens and balances (see right illustration below) which are stored directly in the user's scope. This simplifies the query of all token balances for a user.
We provide two repositories:
- contract: Contains the smart contract which is deployed on the eosio chain
- javascript: Contains a small module to easily interface our smart contract with eos-transit