ERC777 Token Standard

[jbaylina]

Please, see https://eips.ethereum.org/EIPS/eip-777 for further discussion.

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[tjayrush]

Was there discussion of adding a Mint/Burn pair of events and/or mint/burn functions to this proposed standard?

If this was discussed and rejected, what are the reasons for rejecting it? If it was not discussed, should it have been?

While not foolproof (because a contract may neglect to call these events), it would make the automated accounting of ICO sales for token contracts that do comply a lot easier. To accurately account for existing ERC 20 token sales, one must read and understand the contract's code.

[3esmit]

What is the use of _to while is obvious that is the TokenFallback reciever itself (the contract address(this)), and why is needed _ref if we can store a _ref data inside _data if application needs it?

I would find better to stick to the needed stuff, such as:

    /**
    * @notice ERC223 and ERC667 Token fallback 
    * @param _from sender of token
    * @param _amount value sent
    * @param _data data sent
    **/    
    function tokenFallback(
        address _from,
        uint _amount,
        bytes _data
    )

Can you describe situations where _ref and _to are important, or crucial?

[jbaylina]

@3esmit The _to is because the proxy that handles the interface for a specific address can be a different contract. Please see EIP #672 .

For the _ref, this should act as a reference, for example a check number, or an invoice number. In general the ref will be set by the operator and the data will be set for the sender and will be the equivalent to the data in an ethereum transaction.

May be a good alternative would be to integrate this 2 parameters in data and define a standard for data This way we would maintain current compatibility with EIP223...

[3esmit]

I suggest also adding a boolean return to tokenFallback, and token contract require a true return to accept transaction, in order to avoid this scenario: dapperlabs/cryptokitties-bounty#3

[jbaylina]

@3esmit This is problematic. This function is called after the transfer is done. So returning false would mean to rollback the transfer. This can add a lot of reentrance issues, so I decided that the function ether executes or throws the full transaction.
The nice thing of this standard is that if the tokens a sent via send it eans the the receiver must register the interface in EIP672 way. If not, it fails. Of course you can use the old transfer method for backwards compatibility.

[izqui]

I propose renaming operatorData to logData to make more explicit that the purpose of that data is no other than being part of a log. The ability of adding context to token transfers is powerful, and the gas hit is minimal when they are not used.

Really like and support this proposal, exactly the vision that made me excited about ERC223 10 months (!!!) ago. We are considering making ERC777 the base standard for all the tokens issued on @aragon!

[onbjerg]

This is an interesting proposal, but I worry about the entire ecosystem having to migrate to new multisig wallets in order to be able to receive ERC777 tokens.

It seems like there was an attempt made to create a whitelist of contracts that one can safely transfer to even if they do not implement ITokenReceipient:

The function MUST throw if:

• to is a contract that is not prepared to receive tokens. That is it is a contract that does not implements ITokensReceived interface and the hash of the sourcecode is not in between the whitilisted codes listed in the appendix of this code.

But there is no such appendix, I would love to see it 😊

[jbaylina]

@onbjerg We are working on it. We are thinking in keeping this list open for a while (centralized) and close the list at some point (make it decentralized).

[sohkai]

Was there any consideration over allowing users to specify how much an operator can control, e.g. changing authorizeOperator() to:

function authorizeOperator(address operator, uint authorizedAmount) public?

One could use 2^256 - 1 (or hypothetically the totalSupply() if that never grows) to simulate the previous true behaviour and 0 for false.

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The only difference for new contracts implementing ERC20 is that registration of ITokenRecipient via EIP-672 takes precedence over ERC20. This means that even with on a ERC20 transfer call, the token contract MUST check via EIP-672 if the to address implements tokensReceived and call it if available.

I find this somewhat confusing and unexpected. We'll have a dichotomy of "ERC20" tokens: ones that will never call the tokensReceived() callback, even if ITokenRecipient is registered; and ones that will always check. Even if the ERC20 functions are only supposed to be called via old contracts, I think there'll be lots of confusion about this since the meaning of what an "ERC20" token will have essentially changed depending on if your token also supports EIP777.

It also feels odd because you don't have to support the ERC20 interface with EIP777, but you most likely will to support prior contracts expecting that standard.

What if EIP777 was instead a superset of ERC20's interface but overrided specific parts, e.g. transfer() and transferFrom(), to support the ITokenRecipient interface?

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I kind of like and dislike the send() nomenclature. On one hand, it's nice how it parallel's ETH's transfer() and send() nomenclature. On the other, it's confusing because these two terms are now both overloaded with different meanings for ETH and tokens. It's confusing enough that we have both for ETH, but it's going to be even more confusing when there's the same names for tokens. I do like the naming for transferAndCall() because it's really obvious what it's probably going to do.

I guess an alternative could be transferToRecipient().

[jbaylina]

@sohkai:
1.- The idea o authorizeOperator is mainly to authorise a contract.
The maximum allowed limitation and many others limitations, like a daily limits, should be implemented in the operator contract and keep this standard as clean as possible.

2.- The idea is that the receiver should have the warranty that the tokensReceived() method is ALWAYS called. Even if it is called via an obsolete ERC20 transfer() or transferFrom() method. This way, for example, allows a recipient to NEVER accept a specific token. or forward some tokens to a specific charity.

3.- The big problem of maintaining transfer() name in the new standard is that if you use transfer() in an ERC20 only token, you will end up locking a lot of tokens. This mistake might become very common in a moment where 50% of the tokens are ERC20Only and 50%ERC777.

[MicahZoltu]

As I have mentioned in other threads, I strongly recommend removing decimals. Here is a cross post of what I have said elsewhere:

Decimals are easily the number one source of confusion for both token authors and users of ERC20. I strongly recommend removing this as a variable and instead asserting that tokens must have a certain "humanizing divisor". Reasonable choices IMO are:

• 0 - The purpose of decimals is to humanize a very large number, nothing more. If you issue a bunch of your tokens, then people can work with gigatokens instead of tokens. People are used to this already with hard drives (no one talks about hard drive size in bytes, it's gigabytes or terrabytes). This scales with the system and allows it to easily change with time.
• 10^24 - This Allows the token to center on a range that is maximally within the accepted SI prefixes, ranging all the way from yoctotokens to yottatokens. From a scientific/mathematics standpoint, this is probably the best option.
• 10^18 - 10^18 is the most common humanizing divisor, and it is what ETH used. In order to limit confusion, there may be value in asserting that everyone should just use this. While this isn't a particularly optimal choice, it is fairly compelling due to ETH choosing it.
• 10^2 - Most fiat currencies use cents, in general, population is more used to currencies with 2 decimals than 0 or more than 2. I'm including this for completeness, but it ends up being effectively the same as 0.

I think the worst option is to continue to allow for variable humanizing divisors. This doesn't actually solve any real problems, since any chosen unit is very likely to be a wrong choice at some point in time (too big or too small). Also, since the token author can pick the token supply, allowing them to also choose the humanizing divisor doesn't give them any more/less power to try to target a "nice human-scale number".

[MicahZoltu]

You mention function send(address to, uint256 value, bytes userData, bytes operatorData) public; in the interface but it doesn't appear in the function descriptions below. Perhaps it was meant to be replaced by operatorSend but you forgot to delete it from the interface?

[MicahZoltu]

I recommend splitting function authorizeOperator(address operator, bool authorized) public; into:

function authorizeOperator(address operator) public;
function revokeOperator(address operator) public;

At the callsite, this will provide a lot more clarity as to what is happening.