Ethereum Contract

|Build Status| |Documentation Status| |PyPi version|

Python utilities for working with the Ethereum ABI

Installation

.. code:: sh

pip install cpc-abi

Documentation

Decoding

These functions are intended for decoding return values from the EVM.

-  ``eth_abi.decode_single(type, data)``

This function tries to decode ``data`` into the python type that
corresponds to the provided ``type``. This function accepts data of type
bytes.

.. code-block:: python

::

   >>> decode_single('uint256', b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0009')
   12345

The **value** parameter is expected to be one of the recognized EVM
types.

.. note:: This function cannot be used to decode dynamic or array types
such as ``bytes32[]``.

-  ``eth_abi.decode_abi(types, data)``

This function decodes ``data`` into the python type corresponding to the
provided ``types``. This function accepts arrays of type byte.

.. code-block:: python

::

   >>> decode_abi(['uint256'], b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0009')
   [12345]
   >>> decode_abi(['bytes32', 'bytes32'], b'a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00b\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
   ['a', 'b']

The **values** parameter is expected to be an iterable whose values are
all one of the recognized EVM types.

Encoding

These functions are intended for encoding python values into representations that are suitable for interacting with the EVM.

• eth_abi.encode_single(type, value)

This function encodes value in the ABI encoding for the provided type.

.. code-block:: python

::

encode_single('uint256', 12345) b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0009'

The value parameter is expected to be one of the recognized EVM types.

.. note:: This function cannot be used to encode array types such as bytes32[].

• eth_abi.encode_abi(types, values)

This function encodes values in the ABI encoding for the corresponding type provided by the types argument.

.. code-block:: python

::

encode_abi(['uint256'], [12345]) b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0009' encode_abi(['bytes32', 'bytes32'], ['a', 'b']) b'a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00b\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

The values parameter is expected to be an iterable whose values are all one of the recognized EVM types.

Development

Clone the repository and then run:

.. code:: sh

pip install -e . -r requirements-dev.txt

Running the tests

You can run the tests with:

.. code:: sh

   py.test tests

Or you can install ``tox`` to run the full test suite.

Releasing
~~~~~~~~~

Pandoc is required for transforming the markdown README to the proper
format to render correctly on pypi.

For Debian-like systems:

::

   apt install pandoc

Or on OSX:

.. code:: sh

   brew install pandoc

To release a new version:

.. code:: sh

   make release bump=$$VERSION_PART_TO_BUMP$$

How to bumpversion
^^^^^^^^^^^^^^^^^^

The version format for this repo is ``{major}.{minor}.{patch}`` for
stable, and ``{major}.{minor}.{patch}-{stage}.{devnum}`` for unstable
(``stage`` can be alpha or beta).

To issue the next version in line, specify which part to bump, like
``make release bump=minor`` or ``make release bump=devnum``.

If you are in a beta version, ``make release bump=stage`` will switch to
a stable.

To issue an unstable version when the current version is stable, specify
the new version explicitly, like
``make release bump="--new-version 4.0.0-alpha.1 devnum"``

.. |Build Status| image:: https://circleci.com/gh/ethereum/eth-abi.svg?style=shield
   :target: https://circleci.com/gh/ethereum/eth-abi
.. |Documentation Status| image:: https://readthedocs.org/projects/eth-abi/badge/?version=latest
   :target: https://readthedocs.org/projects/eth-abi/?badge=latest
.. |PyPi version| image:: https://img.shields.io/pypi/v/eth-abi.svg
   :target: https://pypi.python.org/pypi/eth-abi