# EIP-712 Derive Macro
This crate provides a derive macro `Eip712` that is used to encode a rust struct
into a payload hash, according to [https://eips.ethereum.org/EIPS/eip-712](https://eips.ethereum.org/EIPS/eip-712)
The trait used to derive the macro is found in `ethers_core::transaction::eip712::Eip712`
Both the derive macro and the trait must be in context when using
This derive macro requires the `#[eip712]` attributes to be included
for specifying the domain separator used in encoding the hash.
NOTE: In addition to deriving `Eip712` trait, the `EthAbiType` trait must also be derived.
This allows the struct to be parsed into `ethers_core::abi::Token` for encoding.
# Optional Eip712 Parameters
The only optional parameter is `salt`, which accepts a string
that is hashed using keccak256 and stored as bytes.
# Example Usage
```ignore
use ethers_contract::EthAbiType;
use ethers_derive_eip712::*;
use ethers_core::types::{transaction::eip712::Eip712, H160};
#[derive(Debug, Eip712, EthAbiType)]
#[eip712(
name = "Radicle",
version = "1",
chain_id = 1,
verifying_contract = "0x0000000000000000000000000000000000000000"
// salt is an optional parameter
salt = "my-unique-spice"
)]
pub struct Puzzle {
pub organization: H160,
pub contributor: H160,
pub commit: String,
pub project: String,
}
let puzzle = Puzzle {
organization: "0000000000000000000000000000000000000000"
.parse::()
.expect("failed to parse address"),
contributor: "0000000000000000000000000000000000000000"
.parse::()
.expect("failed to parse address"),
commit: "5693b7019eb3e4487a81273c6f5e1832d77acb53".to_string(),
project: "radicle-reward".to_string(),
};
let hash = puzzle.encode_eip712().unwrap();
```
# Limitations
At the moment, the derive macro does not recursively encode nested Eip712 structs.
There is an Inner helper attribute `#[eip712]` for fields that will eventually be used to
determine if there is a nested eip712 struct. However, this work is not yet complete.