eth-brownie struct encoding example

Overview

This repository contains an example of encoding a struct, so that it can be used in a function call, using the eth-brownie framework for Solidity smart contract development (https://github.com/eth-brownie/brownie).

Running tests

Run brownie test

Files

1. contracts/StructTest.sol - contains the test smart contract that defines a struct type, and a pure function that accepts the struct type as an argument, and returns its values as a tuple.
2. tests/test_struct_encoding.py - contains a test which does the actual struct encoding and function calling.

How to encode structs with eth-brownie

brownie actually handles encoding for you, in almost all cases. To call a smart contract function that accepts a struct as a parameter, pass in a tuple that contains the correct data types in order.

Refer to the test_struct test in tests/test_struct_encoding.py for an example.

How did I figure this out?

No documentation exists on encoding structs in brownie (that I could find). The intuition came from knowing how Solidity encodes structs, which is just a packed encoding, where each variable in the struct is stored sequentially. I guessed that brownie would just transparent accept the variables with the correct data type in order, and it happened to work.

What about ApeSafe?

ApeSafe uses brownie under the hood -- specifically the brownie.Contract class for crafting transactions, which is what we're also using in our tests. So, in theory, encoding structs should function exactly the same.

ApeSafe is being a pain to set up, so I haven't been able to directly test it, but it should be the same.