Ken Codes

Maker of things. Tinkerer @0xMeem. KB7 fellow @Kernel0x.

https://github.com/meemproject/epm/

Ethereum Package Manager Open Sourced

*The future of smart contract development is composability.*

## TL;DR <https://epm.wtf>

Last year I was experimenting with keeping NFT metadata entirely on-chain when I hit the [24kb EVM smart contract size limit](https://ethereum.org/en/developers/tutorials/downsizing-contracts-to-fight-the-contract-size-limit/). This limitation led me to try various workarounds like deploying libraries and additional contracts that call each other. It was messy to maintain and a nightmare to iterate on the contract code.

Searching for a better way, I stumbled on [the (EIP-2535) Diamond Proxy Pattern](https://eip2535diamonds.substack.com/p/introduction-to-the-diamond-standard), created by [Nick Mudge](https://twitter.com/mudgen), which changed everything. Upgradability, infinite contract size, shared contracts. My mind was blown. 🤯

Since then, I've used the  Diamond Pattern in all my smart contracts. Along the way I've developed a bunch of command line scripts to swap out functions ("diamond cuts") and automate some of the more tedious parts of iterating on and testing contracts. **But it still felt clunky.** And that's why I developed EPM.

## The Vision 👀

With a few clicks on a webpage, combine smart contracts created by other people (or myself) into my own contract. Maximize re-usability, minimize attack surface, and [DRY](https://en.wikipedia.org/wiki/Don%27t_repeat_yourself).

## Features 💡

With EPM you can deploy a Diamond Proxy, attach facets to it, and then get even more granular by toggling functions on or off!

See it for yourself: <https://epm.wtf/manage?address=0xcf169E3D03e46df50f609Ac3b49B66f453E5b6fc&chainId=137>

*Note: You won’t be able to edit anything since you don’t own the contract.*

 ![](https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9BOZqewiVaItELpDhlBV%2Fuploads%2FuslBgkSepAVfKBhCTfOT%2FScreen%20Shot%202022-08-17%20at%209.53.49%20AM.png?alt=media&token=52bc26cc-d3a5-4d47-8205-8b73837a1473)

### Generate Code

Another area of development I found tedious was generating Typescript types for my contracts. With EPM you can download the combined types or ABI (all facet ABIs concatenated) with a click. Just for good measure, there's also a code example of integrating into a React app.

 ![](https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9BOZqewiVaItELpDhlBV%2Fuploads%2FIJohDIB1zOB3Dd62FQiq%2FScreen%20Shot%202022-09-07%20at%209.53.42%20AM.png?alt=media&token=d7d501d6-23ac-4863-a600-3f82526ea8eb)

### Bundles

Combine facets, toggle functions, and save that configuration for easy deployment by you or someone else!

<https://epm.wtf/bundles>

 ![](https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9BOZqewiVaItELpDhlBV%2Fuploads%2Ftf0HVXTpGaKiX5P6VLgG%2FScreen%20Shot%202022-08-18%20at%208.12.05%20AM.png?alt=media&token=cb7f4428-a6db-49e0-a9b3-2402a318be07)

### Other Uses

EPM supports uploading and deployment of **any smart contract**. That means you can also use it for non-diamond contracts.

 ![](https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9BOZqewiVaItELpDhlBV%2Fuploads%2FLU9XQ8F6XCH6rWwqV1QV%2FScreen%20Shot%202022-09-07%20at%2011.22.40%20AM.png?alt=media&token=6036ed37-7cf4-42ab-902e-4b3a98ff7e6a)

## Use Cases

### Inheritance By Overriding Functions

I've been experimenting with a sort of inheritance between contracts by having a base contract that implements a function, say `handleSaleDistribution(...)`, and a second contract that implements the same function. I turn the function off in the base contract and on in the second contract. Then, from the base contract I can still call the method.

These don't have to both be contracts written by you. It could be that `BaseFacet` was uploaded to EPM by someone else. You just need to create `OverrideFacet` with a single function.

The catch with using this pattern is that it requires you to call the function a little differently in the base contract:

**BaseFacet.sol**

```sol
contract BaseFacet {
	function handleSaleDistribution(address msgSender) public payable {
		if (msg.value == 0) {
			return;
		}

		// By default, send the funds back to the sender
		// Important: Do not use msg.sender here which will be this contract instead of the user initiating the transaction
		payable(msgSender).transfer(msg.value);
	}

	function mint() public payable {
		// ... minting logic

		// IMPORTANT: Call the method using this pattern instead of directly
		BaseContract contract = BaseContract(address(this));
		contract.handleSaleDistribution{value: msg.value}(msg.sender);
	}
}
```

**OverrideFacet.sol**

```sol
contract OverrideFacet {
	function handleSaleDistribution(address msgSender) public payable {
		if (msg.value == 0) {
			return;
		}

		// Send all funds to Gitcoin
		payable(0xde21F729137C5Af1b01d73aF1dC21eFfa2B8a0d6).transfer(msg.value);
	}
}
```

### Contract Administration

A simpler use case would be keeping an NFT mint off until a contract admin manually flips the switch on by enabling the corresponding function on the Diamond.

### Shared Business Logic

It may already be obvious, but it's worth reiterating that Diamond Facets *can be shared* by multiple Diamond Proxies! This reduces the amount of duplicate code that needs to be deployed and by extension lowers deployment costs.

[Nick Mudge just wrote about this](https://eip2535diamonds.substack.com/p/reusable-on-chain-facets-for-smart)

 ![](https://2213238710-files.gitbook.io/\~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F9BOZqewiVaItELpDhlBV%2Fuploads%2F7pjiBjRUCLczq4yOkKaS%2Fimage.png?alt=media&token=faa47924-218a-432a-8872-267c8d92384a)

## Related Projects

I'm part of [Meem](https://build.meem.wtf/), a group of amazing people working to define the relationships between assets and humans with smart contracts. One of our other projects is [Clubs](https://clubs.link/) which provides tools for online communities.

Behind the scenes, [Clubs](https://clubs.link/) is using EPM and the [Meem API](https://meem.gitbook.io/meem-protocol/meem-api/graphql-query-api) to manage contracts and upgrades. That means you can start with a Clubs contract and customize it with EPM to suit your needs. For more info read how to [Customize your Clubs Contract with EPM](https://meem.gitbook.io/meem-protocol/epm/epm-walkthrough/customize-clubs-contract).

## EPM Documentation 📚

The most up to date information about EPM, Meem, and Clubs.

[EPM Documentation](https://meem.gitbook.io/meem-protocol/epm/ethereum-package-manager)

[API Endpoints](https://meem.gitbook.io/meem-protocol/meem-api/api-endpoints-reference)

## Considerations 🤔

* Careless upgrades that use [Diamond Storage](https://dev.to/mudgen/how-diamond-storage-works-90e) can cause data corruption in the data stored in the contract (🤦‍♂️ speaking from experience here). It's important to understand exactly how storage works and follow best practices to prevent issues.

## Next Steps 🚀

It’s still early and there's a bunch of improvements that can be made to EPM. Just a few that come to mind are...

* Design / UX updates (in progress)
* Support more constructor data types when deploying contracts
* Verified contracts / creators
  * Show audits
  * Links to source code
* Better "my contracts" contract management / searching
* Facet compatibility info / warnings
  * Ensure upgrades do not destroy data
* Decentralized data source
  * Currently Meem maintains the database for EPM but ideally it would live in a decentralized database or shared data storage like IPFS

Have an idea? Want to help develop EPM? Let's chat!

## Links

[EIP-2535 Further Reading](https://meem.gitbook.io/meem-protocol/epm/eip-2535-further-reading)

[EIP-2535 Resources](https://github.com/mudgen/awesome-diamonds)

> **Get in touch**
>
> Twitter: [@kengoldfarb](https://twitter.com/kengoldfarb)
>
> Email: [hello@kengoldfarb.com](mailto:hello@kengoldfarb.com)
>
> Github: [kengoldfarb](https://github.com/kengoldfarb)
>
> [Farcaster](https://www.farcaster.xyz/): @kencodes

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Ethereum Package Manager Open Sourced

Introducing Ethereum Package Manager (EPM)