单个合约中多个代币的 ERC20

Question

I am trying to make a contract that has two different tokens used for different aspects of the contract. I would like both of the tokens to be able to fit ERC20 standards but I am not sure how to specify unique variables and functions for each.

Answer 1

If you consider the structure of an ERC 20 token : https://github.com/ConsenSys/Tokens/blob/master/Token_Contracts/contracts/Token.sol , you will see that what you are proposing, although possible, would be a little messy. But more importantly it would transform your token contract into a non-ERC20 token .

uint256 public totalSupply; would need to be replaced with either a mapping or a two separate parameters.

The same would be for managing balances, you would need to change the signature of each method to take an additional parameter for specifying the token you want or create specific method for each token within the contract:

function balanceOf(address _owner) constant returns (uint256 balance);

Would need to be either:

function balanceOf(address _owner, uint256 token_id) constant returns (uint256 balance);

or

function balanceOfTokenA(address _owner) constant returns (uint256 balance);

function balanceOfTokenB(address _owner) constant returns (uint256 balance);

But like I said, either implementation would make your token contract a non-ERC20 token.

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You would be better off having two contracts, then both would be ERC20 compatible. You could then write a third contract for managing them if your requirements are that they need to be interfaced via a single contract.

Answer 2

These days, ERC1155, a "multi-token" standard, seems like a good choice for contracts needing multiple tokens:

https://github.com/ethereum/EIPs/issues/1155

Simple Summary:

A standard interface for contracts that manage multiple token types. A single deployed contract may include any combination of fungible tokens, non-fungible tokens or other configurations (eg semi-fungible tokens).

See also the openzeppelin implementation