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Python abstraction for ERC190 packages.

Project description

  • parse and validate packages.
  • given a web3 instance provide access to contract factory classes
  • given a web3 instance provide access to all of the deployed contract instances for the chain that web3 is connected to.
  • validate package bytecode matches compilation output.
  • validate deployed bytecode matches compilation output
  • access to packages dependencies
  • construct new packages


The Package object will function much like the Contract class provided by web3. Rather than instantiating the base class provided by ethpm, you will instead use a classmethod which generates a new Package class for a given package.

OwnedPackage = BasePackage.factory('/path/to/owned-v1.0.0.json')

Then, the OwnedPackage can be instantiated with any web3 intance.

owned_package = OwnedPackage(web3)

A Package class can only be directly constructed from the parsed package JSON. It can also be initialized with the package’s URI or the local filesystem path to a package by using Package.from_file(path).

Contract Factories

Contract factories should be accessible from the package class but you must also provide a web3 instance.

Owned = OwnedPackage.get_contract_factory(web3, 'owned')

From a package instance, they are also available as properties.

Owned = owned_package.contract_factories.owned

In cases where a contract uses a library, the contract factory will have unlinked bytecode. The ethpm package ships with its own subclass of web3.contract.Contract with a few extra methods and properties related to bytecode linking

>>> math = owned_package.contract_factories.math
>>> math.has_linkable_bytecode
>>> math.is_bytecode_linked
>>> linked_math = math.link_bytecode({'MathLib': '0x1234...'})
>>> linked_math.is_bytecode_linked
Note: the actual format of the link data is not clear since library names aren’t a one-size-fits all solution. We need the ability to specify specific link references in the code.

Deployed Contracts

Deployed contracts are only available from package instances. The package instance will filter the deployments based on the chain that web3 is connected to.

Accessing deployments is done with property access



We’ll need a pluggable backend system for IPFS access. A built-in default one that defaults to using infura should be enough to get off the ground.

Lower priority but important will be ensuring that a user can configure connecting to their own IPFS node.

Verifying Things

The Package class should verify all of the following things.

  • Package json matches EthPM V2 Manifest Specification
  • Included bytecode matches compilation output
  • Deployed bytecode matches compilation output


The Package class should provide access to the full dependency tree.

>>> owned_package.build_dependencies['zeppelin']

Testing Strategy

  • Load and validate packages from disk.
  • Access package data.
  • Access contract factories.

Project details

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