amsgpack 0.3.3

Another MessagePack library

Python MessagePack module

C library for python 3.10+.

Why:

• I couldn't negotiate adding type hints to msgpack-python
• I couldn't negotiate adding Unpacker to ormsgpack
• There's no stream unpacking in msgspec
• I couldn't find another MessagePack library
• msgpack-python interfaces are messy and the library is a bit slow

Installation

pip install amsgpack

Documentation

https://amsgpack.readthedocs.io/

Examples

>>> from amsgpack import packb, unpackb
>>> packb({"compact": True, "schema": 0})
b'\x82\xa7compact\xc3\xa6schema\x00'
>>> unpackb(b'\x82\xa7compact\xc3\xa6schema\x00')
{'compact': True, 'schema': 0}

>>> from amsgpack import FileUnpacker
>>> from io import BytesIO
>>> for data in FileUnpacker(BytesIO(b'\x00\x01\x02')):
...     print(data)
...
0
1
2

>>> from amsgpack import Unpacker
>>> unpacker = Unpacker()
>>> unpacker.feed(b'\x82\xa7compact\xc3\xa6schema\x00')
>>> next(unpacker)
{'compact': True, 'schema': 0}

Ext Type Packing

When encountering unsupported type a default callback is called:

>>> from typing import Any
>>> from amsgpack import Ext, Packer
>>> from array import array
>>>
>>> def default(value: Any) -> Ext:
...     if isinstance(value, array):
...         return Ext(1, value.tobytes())
...     raise ValueError(f"Unserializable object: {value}")
...
>>> packb = Packer(default=default).packb
>>> packb(array('I', [0xBA, 0xDE]))
b'\xd7\x01\xba\x00\x00\x00\xde\x00\x00\x00'

Ext Type Unpacking

By default when encountering Ext type, a conversion to datetime.datetime happens when code == 1, otherwise Ext instance is returned.

>>> from amsgpack import Ext, Unpacker
>>> from array import array
>>>
>>> def ext_hook(ext: Ext):
...     if ext.code == 1:
...         return array("I", ext.data)
...     return ext.default()
...
>>> Unpacker(ext_hook=ext_hook).unpackb(
...     b"\xd7\x01\xba\x00\x00\x00\xde\x00\x00\x00"
... )
array('I', [186, 222])

Benchmark

Run amsgpack_benchmark.py and then chart.py to get your values