Add support for ethPM

[iamdefinitelyahuman]

...because it's awesome.

Proposed Functionality

Deployment Interaction:

• query a registry for an ABI and contract address, and returns a Contract object
• query a registry and generate a Project from the entire manifest, including Contract objects for deployed contracts

Registry Interaction:

• list all known registries
• list all packages in a registry
• search a registry for a package / version
• list locally available packages

Project integration:

• add packages to a project via brownie ethpm install [uri]
  • store package source code inside a project's contracts/ directory
  • track installed packages in build/packages.json, warn the user loudly when source in an installed package has been modified
• generate and publish a package from a project
• allow references to installed package by name/alias

Bonus points:

• re-introduce deployment persistence (Persist #246)
• create a Brownie registry: pm.eth-brownie.eth
• create a test registry on Roptsen

Useful Links

• official documentation
• EthPM Package Manifest Documentation
• original EIP spec
• web3.py: package manager / ethPM
• how Truffle did it
• Dai manifest that includes dependencies

[iamdefinitelyahuman]

WIP branch - https://github.com/iamdefinitelyahuman/brownie/tree/ethpm

[iamdefinitelyahuman]

per devcon conversation, the current proposed uri format:

erc1319://[CONTRACT_ADDRESS]:[CHAIN_ID]/[PACKAGE_NAME]@[VERSION]/[PATH]

[iamdefinitelyahuman]

• allow import commands in source code that reference packages: (uri docs) import "erc1319://[CONTRACT_ADDRESS]:[CHAIN_ID]/[PACKAGE_NAME]@[VERSION]/[PATH]"
  • for inheritance / libraries (sources/[PATH])
  • for contract -> contract interaction (contract_types/[CONTRACT_NAME]/abi, requires abi2solc)

The more I think about this, it's not the best approach:

• It requires path remapping when compiling, which limits the use of the contract outside Brownie
• It will be very confusing to some users
• When generating a package from a project, import statements will have to be modified or remappings included in compiler settings for each contract - again, creating barriers with other tooling

My new, simpler idea:

• Add packages to a project via brownie ethpm install [uri]
• Store package source code inside a project's contracts/ directory
• Track installed packages in build/packages.json and warn the user loudly when source in an installed package has been modified

I think this will be more understandable to users, and it will be much simpler to generate packages from projects that use dependencies.

UPDATE: old approach removed in 36f0ec5