netcast is a Python package for many purposes related to the processing of structured data. It provides a light-weight, simple API for designing abstract, multi-component, contextual and adaptable data structures, the individual branches of which are configurable and easily interchangeable.
netcast introduces an independent typing system that is roughly similar to the Python data model. With its help, you can easily separate fixed schemas from changing standards, thus applying the principles of SOLID, KISS and DRY.
It depends only on the used driver, i.e. the implementation dealing with the actual processing of the data in real time. The library itself only manages to bind components and put assigned values to the proper places inside them during the runtime.
This is an example implementation of a data model with netcast.
import netcast as nc
class Foo(nc.Model):
bar = nc.String()
baz = nc.Int()
biz = nc.Char(signed=False)
ext = nc.Int(version_added=2, default=20)
driver = "construct"
sent_inst = Foo(bar="bar", baz=1, biz=2, ext=3)
# Dumping - returned values are :attr:`serializer.dump_type` instances (bytes)
sent_v1 = sent_inst.dump(driver, version=1) # b'bar\x00\x01\x00\x00\x00\x02'
sent_v2 = sent_inst.dump(driver) # b'bar\x00\x01\x00\x00\x00\x02\x03\x00\x00\x00'
# Loading the returned values to the :class:`Foo` instances
recv_v1 = Foo().load(driver, sent_v1, version=1)
recv_v2 = Foo().load(driver, sent_v2)
assert recv_v1 == Foo(bar="bar", baz=1, biz=2, ext=20)
assert recv_v2 == sent_inst
# Various functions of drivers (an example of construct-specific features)
# Changing the endianness dynamically (for each field)
big_endian_sent = sent_inst.dump(driver, big_endian=True) # b'bar\x00\x00\x00\x00\x01\x02\x00\x00\x00\x03'
big_endian_recv = Foo().load(driver, big_endian_sent, big_endian=True)
assert big_endian_recv == sent_inst
# Changing the signedness dynamically
signed_inst = Foo(bar="bar", baz=-1, biz=-2)
signed_inst.dump(driver, signed=True) # b'bar\x00\xff\xff\xff\xff\xfe\x14\x00\x00\x00'
try:
signed_inst.dump(driver)
except nc.NetcastError: # the 'biz' field is signed, so an error is reported
passnetcast models are build upon special Stack objects, which are accessible from the
Model.stack attribute. In the case shown above, fields bar, baz, biz and ext
created the stack automatically thanks to the Model class inheritance magic inspection,
but it is not obligatory – dependency injection is welcome.
This little trick allows to present the model as a list of components. Components can be either
Serializer or Model objects. You can nest models and impose custom settings on them
(like version_added=2), which will be propagated to all the components inside, recursively.
Those configurations will influence serialization and deserialization of any considered netcast
data model.
Having jumped to dump_v1 assignment line, you can see the version=1 parameter. It means
that the context of the dumped model has version equal to 1. That's why ext neither
gets dumped nor loaded.
Looking for developers! Please feel free to contribute in any way – issues, PRs, suggestions.
Not finished.
Serious development of netcast started in December 2021, a few months after a few ideas connected with parsing and building data packets came up to my mind when I had been programming the TCP/UDP network protocol for the multiplayer game named Jazz Jackrabbit 2.