Iterable Eternal Storage

This library provides Solidity smart contracts for eternal storage with iterable functionality.

The aim is to provide smart contracts, which only contain the data of an application. Through the separation of logic and data make the dApp is upgradable.
To make the data itself upgradable the library provides the functionality to add iterable keys. This way the data can be iterated over and changed if necessary.

Usage

The eternal storage needs to be deployed first. After that the address of the logic smart contract, which wants to use it, has to be set by calling upgradeVersion.
With truffle console this is done with:

EternalStorage.new().then((c) => {eternalStorage = c})
eternalStorage.upgradeVersion(LOGIC_CONTRACT_ADDRESS)

// or

IterableEternalStorage.new().then((c) => {iterableEternalStorage = c})
iterableEternalStorage.upgradeVersion(LOGIC_CONTRACT_ADDRESS)

Eternal storage

The following example shows the usage of the eternal storage library with the uint256 data type.

import "IEternalStorage.sol";

contract Example {
    IEternalStorage internal eternalStorage;

    constructor(IEternalStorage _storage) public {
        eternalStorage = _storage;
    }
    
    function addToX(uint256 value) external {
        uint256 x = eternalStorage.getUInt256(keccak256(abi.encodePacked("X")));
        x = x + value;
        
        eternalStorage.setUInt256(keccak256(abi.encodePacked("X")), x);
    }
    
    function getX() public view returns (uint256) {
        return eternalStorage.getUInt256(keccak256(abi.encodePacked("X")));
    }
    
    function resetX() public {
        eternalStorage.deleteUInt256(keccak256(abi.encodePacked("X")));
    }
}