Updatable contract example

A demo solidity and test codes to upgrade the delegate contract. The codes and contracts are explained by Himanshu Chawla in Medium. https://medium.com/quillhash/how-to-write-upgradable-smart-contracts-in-solidity-d8f1b95a0e9a

Requirements

The code is written in solidity version 0.4.23 and the test uses async/await functions. You may need node version above 7.6 to run those functions.

Here's information of workable environment of mine.

node --version v10.13.0

npm --version 6.4.1

Contracts

KeyStorage contract contains a common storage for all storage state variables that will be shared among all delegate contracts. It also has getter and setter functions to update and obtain values of state from delegate contracts. DelegateV1/V2 contracts are implemented to run the actual functions of Dapps. DelegateV1 has been deployed but a bug was found. DelegateV2 is new version of the delegate contract and our aim is to replace the delegate contract which has application logics with newer contract. As an address change due to replacement of the delegate contracts, ProxyContract takes place to use the delegatecall opcode to forward functions calls to a target contract which was updatable. The delegatecall retains the state of the function call, the target contract logics can be updated and the state will remain in the proxy contract for the updated target contract logics to use.

To Migrate:

Run: truffle develop under the application root
In the development console run: compile
Next run: migrate or (migrate --reset)

To Test:

Migrate the contracts in the truffle development blockchain
truffle test or test in the truffle development console

License

This code is licensed under the MIT License.

yuyasugano / updatable-solidity