How it works · Try it · What is tested · Known issues

Contract Ledger lets a person or a contract keep an on-chain list of contract addresses. An app with many contracts can keep them in one place, and a front end can read that list instead of hard-coding the addresses. The same pattern also stores lists of token IDs or strings.

Warning

This is a proof of concept. It has not been audited and has not run on a real network. Everything in a ledger is public.

How it works

flowchart LR
    K[Key holder] -->|addContract| U[LedgerUser]
    U -->|numbered entry| E[Addresses, time, ID]
    R[Anyone] -->|viewLedgerID| U

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Contract	Use	Add function	Read function
LedgerUser	Ready to deploy. Holding a key token allows adding	addContract(addresses)	viewLedgerID(id)
LedgerContract	Inherit it for lists of addresses	Internal addContract	viewLedgerID(id)
LedgerContractToken	Inherit it for lists of token IDs	Internal addTokenInt	viewIntLedgerID(id)
LedgerContractData	Inherit it for lists of strings	Internal addData	viewDataLedgerID(id)

Every read returns the list, the time it was added, its ID and whether it exists. Each add emits an event carrying the ID, because a wallet cannot read a function's return value.

The base contracts have no access control of their own. Whoever inherits them decides who may add.

Try it

git clone https://github.com/CoinClubQuincy/ContractLedger.git
cd ContractLedger
git clone --depth 1 -b v4.9.6 https://github.com/OpenZeppelin/openzeppelin-contracts lib/openzeppelin-contracts
git clone --depth 1 -b v1.9.7 https://github.com/foundry-rs/forge-std lib/forge-std
forge test

You need Foundry.

What is tested

test/foundry/Ledger.t.sol has 12 tests, including one fuzz test, and runs in CI on every push.

Tested	Not tested
Adding and reading in all four contracts	A real network, testnet or mainnet
Key access, and access moving with the key	An independent security audit
Refusing empty entries and zero keys
Entries that do not exist, and events
Fuzz: IDs count up and entries stay separate

Changes from earlier versions

Contracts already deployed are unaffected and keep the old behaviour.

• The three base ledgers are now abstract. They could be deployed before, but nothing could ever be added to them.
• Each add emits an event with its ID, and empty lists are refused.
• LedgerUser refuses zero keys, which would have left nobody able to add.
• The Hardhat template (Lock.sol, its test and its script), the broken test/LedgerContract.js, the Hardhat config and package files, and tracked node_modules were removed. Foundry is the supported test path.

Known issues

Issue	Effect
Entries cannot be edited or removed	A mistake stays in the ledger. Add a corrected entry and have readers use the latest
Anyone holding a key can add	Keys are all equal, and there is no way to take one back
Addresses are not checked	An entry can name an address that is not a contract

More XDC and EVM projects

Group	Project	What it is
Standards	XRC-SHARES	Dividend-paying NFT shares and SPLITS for a DApp
Standards	XRCDividendPlus	Dividend-paying XRC-20 token
Treasury and finance	Multi-Sig-Treasury	Treasury controlled by tokenized keys
Treasury and finance	XRC-Airdrop	Self-run token airdrop
Treasury and finance	XRC-Credit	Single-loan credit contract
Treasury and finance	XDC-Defi-Instruments	Assets, agreements, forwards, futures and a marketplace
Treasury and finance	XRC1155-Equities-Market	Shares, portfolios and a marketplace on ERC-1155
Treasury and finance	NFTOTC	Over-the-counter sale of a token collection
Treasury and finance	DAppProxySwap	Currency swaps for a DApp through a fixed router
Identity and access	LoginMFAContract	Login with an NFT and a signed second factor
Identity and access	PrivateAccessToken	Token access to encrypted off-chain data
Identity and access	Delegated_Authority	KYC notary proof of concept
Identity and access	EncryptedNFT-Documents	NFTs tied to encrypted off-chain documents
Learning and libraries	XDC-LemonadeStand	Workshop DApp built on XRC-SHARES
Learning and libraries	Non-Financial-SmartContracts	Games, inventory, keys and on-chain repositories
Learning and libraries	TimestampConverter	Timestamps to calendar dates in Solidity
Tools	XDC_Python_SDK_V1	Python client for the XDC JSON-RPC API
Tools	PrivateXDCNode_SetupScript	Private XDC network setup scripts
Tools	WebApp_to_XDCPay	Working web app connected to XDCPay
Multi-chain	CoinClub_Framework	Python library with an XDC adapter
Interfaces	Contract_Interface_Model_Language	Interface documents for smart contracts and APIs

License

MIT.