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python-syscoinlib

This Python2/3 library provides an easy interface to the syscoin data structures and protocol. The approach is low-level and "ground up", with a focus on providing tools to manipulate the internals of how Syscoin works.

"The Swiss Army Knife of the Syscoin protocol." - Wladimir J. van der Laan

Requirements

sudo apt-get install libssl-dev

The RPC interface, syscoin.rpc, is designed to work with Syscoin Core v0.13.0 Older versions may work but there do exist some incompatibilities.

Structure

Everything consensus critical is found in the modules under syscoin.core. This rule is followed pretty strictly, for instance chain parameters are split into consensus critical and non-consensus-critical.

syscoin.core            - Basic core definitions, datastructures, and
                          (context-independent) validation
syscoin.core.key        - ECC pubkeys
syscoin.core.script     - Scripts and opcodes
syscoin.core.scripteval - Script evaluation/verification
syscoin.core.serialize  - Serialization

In the future the syscoin.core may use the Satoshi sourcecode directly as a library. Non-consensus critical modules include the following:

syscoin          - Chain selection
syscoin.base58   - Base58 encoding
syscoin.bloom    - Bloom filters (incomplete)
syscoin.net      - Network communication (in flux)
syscoin.messages - Network messages (in flux)
syscoin.rpc      - Syscoin Core RPC interface support
syscoin.wallet   - Wallet-related code, currently Syscoin address and
                   private key support

Effort has been made to follow the Satoshi source relatively closely, for instance Python code and classes that duplicate the functionality of corresponding Satoshi C++ code uses the same naming conventions: CTransaction, CBlockHeader, nValue etc. Otherwise Python naming conventions are followed.

Mutable vs. Immutable objects

Like the Syscoin Core codebase CTransaction is immutable and CMutableTransaction is mutable; unlike the Syscoin Core codebase this distinction also applies to COutPoint, CTxIn, CTxOut, and CBlock.

Endianness Gotchas

Rather confusingly Syscoin Core shows transaction and block hashes as little-endian hex rather than the big-endian the rest of the world uses for SHA256. python-syscoinlib provides the convenience functions x() and lx() in syscoin.core to convert from big-endian and little-endian hex to raw bytes to accomodate this. In addition see b2x() and b2lx() for conversion from bytes to big/little-endian hex.

Module import style

While not always good style, it's often convenient for quick scripts if import * can be used. To support that all the modules have __all__ defined appropriately.

Example Code

See examples/ directory. For instance this example creates a transaction spending a pay-to-script-hash transaction output:

$ PYTHONPATH=. examples/spend-pay-to-script-hash-txout.py
<hex-encoded transaction>

Selecting the chain to use

Do the following:

import syscoin
syscoin.SelectParams(NAME)

Where NAME is one of 'testnet', 'mainnet', or 'regtest'. The chain currently selected is a global variable that changes behavior everywhere, just like in the Satoshi codebase.

Unit tests

Under syscoin/tests using test data from Syscoin Core. To run them:

python -m unittest discover && python3 -m unittest discover

Please run the tests on both Python2 and Python3 for your pull-reqs!

Alternately, if Tox (see https://tox.readthedocs.org/) is available on your system, you can run unit tests for multiple Python versions:

./runtests.sh

Currently, the following implementations are tried (any not installed are skipped):

* CPython 2.7
* CPython 3.3
* CPython 3.4
* CPython 3.5
* PyPy
* PyPy3

HTML coverage reports can then be found in the htmlcov/ subdirectory.

Documentation

Sphinx documentation is in the "doc" subdirectory. Run "make help" from there to see how to build. You will need the Python "sphinx" package installed.

Currently this is just API documentation generated from the code and docstrings. Higher level written docs would be useful, perhaps starting with much of this README. Pages are written in reStructuredText and linked from index.rst.

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