dpack

A dpack is a file with a collection of EVM addresses and artifacts (ABIs).

The most important part of dpack is the dpack-1 file format. It has a simple and final spec that one person can learn in one sitting. New features will be deferred until the next version, which will be backwards compatible.

This repo is a lightweight javascript package which lets you

• assemble dpacks from your deployment info
• easily load and instantiate bindings for dapps

For the time being, we are distributing dpack via npm:

npm i @etherpacks/dpack # WAIT! Read the next paragraph!

WARNING: Please take a minute to reflect on the nature of the software supply chain. What good is dpack if you are loading it via npm? Why not just stick the info in a package.json? There is no 'partially secured', we are either bootstrapped into a secure software supply chain, or not. If you are using npm as currently architected, you are not bootstrapped. But we have to start somewhere, so here we are.

Basic Usage

ipfs daemon must be running. dpack will connect to the default IPFS RPC URL unless one is specified with the environment variable IPFS_RPC_URL.

Loading a dpack:

const dpack = require('dpack');
const dapp = dpack.load(require('./pack/weth_ropsten.dpack.json'))

dapp._objects // all instantiated contract *objects* from this pack
dapp._types   // all artifacts plus ethers.js 'factories'; JS-level objects that deploy new instances of contracts

// objects are also loaded directly onto the dapp object
await dapp.weth.transfer(...)
await dapp._objects.weth.transfer(...)   // equivalent, its the same reference

Putting together a dpack:

const dpack = require('dpack')
const pb = new dpack.PackBuilder('kovan')
// you can also say `const pb = dpack.builder()`

await pb.packType({
  typename: 'Gem',
  artifact: require('./artifact/sol/Gem.sol/Gem.json')
})
await pb.packObject({
  typename: 'GemFab',
  artifact: require('./artifacts/sol/Gem.sol/Gem.json'),
  objectname: 'gemfab',
  address: '0x...'
}, alsoAddType=true)  // alsoAddType argument defaults to true, adds GemFab+artifact to types

const pack = await pb.build();
const pretty = JSON.stringify(pack, null, 2);
console.log(pretty);

dpack format description

A dpack is a JSON file with these fields:

{
  "format": "dpack-1",
  "network" "ethereum",
  "types": { ... },
  "objects": { ... }
}

format

format is currently dpack-1

network

network is the name of the network on which the objects in this dpack are deployed. Future formats will support multi-network packs.

types

types is a collection of named contract types ("classes"). Each object has this form:

"MyToken": {
  "typename": "MyToken"
  "artifact": {"/": "<CID>"}
}

• typename is the name of the type (ie, the Solidity class)
• artifacts is a DAG-JSON link to this type's "artifacts" json file (output of solc/truffle/hardhat).

Note that 'typename' is redundant with key used to name this type in this pack. Typenames are mixedcase alphanumeric and underscores, but must start with an uppercase alphabetic.

objects

objects is a collection of named EVM contract instances. Each object descriptor stores both object information (object name and address) as well as its type information (artifacts and typename).

If an object's typename matches one of the types declared in this same scope (the same dpack), or if multiple objects have the same typename, then the artifacts must also match. This means some typenames and CID's will be recorded redundantly in the pack.

"mytoken": {
  "objectname": "mytoken",
  "address": "<ETH address>"
  "typename": "MyToken",
  "artifact": {"/": "<CID>"}
}

• objectname is the name of the object (a deployed 'contract' with a specific address)
• address is the address of the object
• typename is the name of the type (ie, the Solidity class).
• artifact is a DAG-JSON link to this object's type's "artifacts" json file (output of solc/truffle/hardhat)

Note that 'objectname' is redundant with key used to name this object in this pack. Typenames are mixedcase alphanumeric and underscores, but must start with an uppercase alphabetic. Objectnames are mixedcase alphanumeric and underscores, but must start with a lowercase alphabetic.

Discussion

Much of the Ethereum toolchain ecosystem confuses types and objects just because we call both "contracts".

The prime example of this is the keyword contract in solidity referring to a contract class.

The dpack format makes a clear distinction and is very explicit. You cannot name an object the same as a type.