A python interface for simple EIP-712 struct construction.
In this module, a "struct" is structured data as defined in the standard.
It is not the same as the Python Standard Library's struct (e.g., import struct).
Read the proposal:
https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md
3.63.7
pip install eip712-structsSee API.md for a succinct summary of available methods.
Examples/Details below.
Say we want to represent the following struct, convert it to a message and sign it:
struct MyStruct {
string some_string;
uint256 some_number;
}
With this module, that would look like:
# Make a unique domain
from eip712_structs import make_domain
domain = make_domain(name='Some name', version='1.0.0') # Make a Domain Separator
# Define your struct type
from eip712_structs import EIP712Struct, String, Uint
class MyStruct(EIP712Struct):
some_string = String()
some_number = Uint(256)
# Create an instance with some data
mine = MyStruct(some_string='hello world', some_number=1234)
# Values can be get/set dictionary-style:
mine['some_number'] = 4567
assert mine['some_string'] == 'hello world'
assert mine['some_number'] == 4567
# Into a message dict - domain required
my_msg = mine.to_message(domain)
# Into message JSON - domain required.
# This method converts bytes types for you, which the default JSON encoder won't handle.
my_msg_json = mine.to_message_json(domain)
# Into signable bytes - domain required
my_bytes = mine.signable_bytes(domain)See Member Types for more information on supported types.
Attributes may be added dynamically as well. This may be necessary if you
want to use a reserved keyword like from.
from eip712_structs import EIP712Struct, Address
class Message(EIP712Struct):
pass
Message.to = Address()
setattr(Message, 'from', Address())
# At this point, Message is equivalent to `struct Message { address to; address from; }`EIP-712 specifies a domain struct, to differentiate between identical structs that may be unrelated.
A helper method exists for this purpose.
All values to the make_domain()
function are optional - but at least one must be defined. If omitted, the resulting
domain struct's definition leaves out the parameter entirely.
The full signature:
make_domain(name: string, version: string, chainId: uint256, verifyingContract: address, salt: bytes32)
Constantly providing the same domain can be cumbersome. You can optionally set a default, and then forget it.
It is automatically used by .to_message() and .signable_bytes()
import eip712_structs
foo = SomeStruct()
my_domain = eip712_structs.make_domain(name='hello world')
eip712_structs.default_domain = my_domain
assert foo.to_message() == foo.to_message(my_domain)
assert foo.signable_bytes() == foo.signable_bytes(my_domain)EIP712's basic types map directly to solidity types.
from eip712_structs import Address, Boolean, Bytes, Int, String, Uint
Address() # Solidity's 'address'
Boolean() # 'bool'
Bytes() # 'bytes'
Bytes(N) # 'bytesN' - N must be an int from 1 through 32
Int(N) # 'intN' - N must be a multiple of 8, from 8 to 256
String() # 'string'
Uint(N) # 'uintN' - N must be a multiple of 8, from 8 to 256Use like:
from eip712_structs import EIP712Struct, Address, Bytes
class Foo(EIP712Struct):
member_name_0 = Address()
member_name_1 = Bytes(5)
# ...etcIn addition to holding basic types, EIP712 structs may also hold other structs! Usage is almost the same - the difference is you don't "instantiate" the class.
Example:
from eip712_structs import EIP712Struct, String
class Dog(EIP712Struct):
name = String()
breed = String()
class Person(EIP712Struct):
name = String()
dog = Dog # Take note - no parentheses!
# Dog "stands alone"
Dog.encode_type() # Dog(string name,string breed)
# But Person knows how to include Dog
Person.encode_type() # Person(string name,Dog dog)Dog(string name,string breed)Instantiating the structs with nested values may be done a couple different ways:
# Method one: set it to a struct
dog = Dog(name='Mochi', breed='Corgi')
person = Person(name='E.M.', dog=dog)
# Method two: set it to a dict - the underlying struct is built for you
person = Person(
name='E.M.',
dog={
'name': 'Mochi',
'breed': 'Corgi',
}
)Arrays are also supported for the standard.
array_member = Array(<item_type>[, <optional_length>])<item_type>- The basic type or struct that will live in the array<optional_length>- If given, the array is set to that length.
For example:
dynamic_array = Array(String()) # String[] dynamic_array
static_array = Array(String(), 10) # String[10] static_array
struct_array = Array(MyStruct, 10) # MyStruct[10] - again, don't instantiate structs like the basic typesContributions always welcome.
Install dependencies:
pip install -r requirements.txt
Run tests:
python setup.py test- Some tests expect an active local ganache chain on http://localhost:8545. Docker will compile the contracts and start the chain for you.
- Docker is optional, but useful to test the whole suite. If no chain is detected, chain tests are skipped.
- Usage:
docker-compose up -d(Starts containers in the background)- Note: Contracts are compiled when you run
up, but won't be deployed until the test is run. - Cleanup containers when you're done:
docker-compose down
Deploying a new version:
- Bump the version number in
setup.py, commit it into master. - Make a release tag on the master branch in Github. Travis should handle the rest.
Written by ConsenSys for the world! ❤️
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