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.

Package objects must be instantiated with a valid web3 object.

Creating a Package object from a local manifest file.

>>> from ethpm import Package, V2_PACKAGES_DIR
>>> from web3 import Web3

>>> owned_manifest_path = str(V2_PACKAGES_DIR / 'owned' / '1.0.0.json')
>>> w3 = Web3(Web3.EthereumTesterProvider())

>>> OwnedPackage = Package.from_file(owned_manifest_path, w3)
>>> assert isinstance(OwnedPackage, Package)

Creating a Package object from a content-addressed URI pointing towards a valid manifest.

OwnedPackage = Package.from_uri('ipfs://QmbeVyFLSuEUxiXKwSsEjef6icpdTdA4kGG9BcrJXKNKUW', w3)

To change the web3 instance of a Package.

>>> new_w3 = Web3(Web3.EthereumTesterProvider())
>>> OwnedPackage.set_default_w3(new_w3)
>>> assert OwnedPackage.w3 == new_w3

The following properties are available on a Package object.

>>> OwnedPackage.name
'owned'
>>> OwnedPackage.version
'1.0.0'
>>> OwnedPackage.manifest_version
'2'
>>> OwnedPackage.__repr__()
'<Package owned==1.0.0>'

Contract Factories¶

Contract factories should be accessible from the package class.

Owned = OwnedPackage.get_contract_factory('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
True
>>> math.is_bytecode_linked
False
>>> linked_math = math.link_bytecode({'MathLib': '0x1234...'})
>>> linked_math.is_bytecode_linked
True

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.

Contract Instances¶

To return a contract instance of a contract type belonging to a Package.

owned = OwnedPackage.get_contract_instance('owned', '0x123...')

Deployments¶

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

package.deployed_contracts.Greeter

Dependencies¶

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

>>> owned_package.build_dependencies['zeppelin']
<ZeppelinPackage>

Validation¶

The Package class currently verifies the following things.

Manifests used to instantiate a Package object conform to the EthPM V2 Manifest Specification

And in the future should verify.

Included bytecode matches compilation output
Deployed bytecode matches compilation output