==== EIP 777: ERC-777 Token Standard  ====
[[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip| Return to Ethereum ERCs ]]

  : **Note**: The following is an excerpt from the official Ethereum site. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

<table>
<caption>Data sheet for Token Standard</caption>
| Title                      | Token Standard |
| Author                     | Jacques Dafflon, Jordi Baylina, Thomas Shababi |
| Status                     | Final |
| Created                    | 2017-11-20  |
| Description                | [[http://eips.ethereum.org/EIPS/eip-777]] |
| Specification              | [[http://eips.ethereum.org/EIPS/eip-777#Specification]] |
| Category                   | ERC |
| Requires                   | [[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip:erc_1820|1820]] | 
</table>

=== Abstract === 
//This standard defines a new way to interact with a token contract while remaining backward compatible with ERC20.//

//It defines advanced features to interact with tokens. Namely, operators to send tokens on behalf of another address—contract or regular account—and send/receive hooks to offer token holders more control over their tokens.//

//It takes advantage of [[dido:public:ra:xapend:xapend.b_stds:defact:ethereum:eip:erc_1820|ERC1820]] to find out whether and where to notify contracts and regular addresses when they receive tokens as well as to allow compatibility with already-deployed contracts.//

=== Motivation === 
//This standard tries to improve upon the widely used ERC20 token standard. The main advantages of this standard are://

    * //Uses the same philosophy as [[dido:public:ra:xapend:xapend.a_glossary:e:ether|Ether]] in that [[dido:public:ra:xapend:xapend.a_glossary:t:tokens|tokens]] are sent with send(dest, value, data).//

    * //Both contracts and regular addresses can control and reject which token they send by registering a ''tokensToSend'' hook. (Rejection is done by ''revert''ing in the hook function.)//

    * //Both contracts and regular addresses can control and reject which token they receive by registering a ''tokensReceived'' hook. (Rejection is done by ''revert''ing in the hook function.)//

    * //The tokensReceived hook allows to send tokens to a contract and notify it in a single transaction, unlike ERC20 which requires a double call (''approve''/''transferFrom'') to achieve this.//

    * //The holder can “authorize” and “revoke” operators which can send tokens on their behalf. These operators are intended to be verified contracts such as an exchange, a cheque [[dido:public:ra:xapend:xapend.a_glossary:p:start|processor]] or an automatic charging system.//

    * //Every token transaction contains ''data'' and ''operatorData'' bytes fields to be used freely to pass data from the holder and the operator, respectively.//

It is backward compatible with [[dido:public:ra:xapend:xapend.a_glossary:w:wallet|wallets]] that do not contain the ''tokensReceived'' hook function by deploying a proxy contract implementing the ''tokensReceived'' hook for the wallet.