pycapnp-async
Requirements
-
C++14 supported compiler
- gcc 6.1+ (5+ may work)
- clang 6 (3.4+ may work)
- Visual Studio 2017+
-
cmake (needed for bundled capnproto)
- ninja (macOS + Linux)
- Visual Studio 2017+
-
capnproto-0.7.0
- Not necessary if using bundled capnproto
32-bit Linux requires that capnproto be compiled with -fPIC. This is usually set correctly unless you are compiling canproto yourself. This is also called -DCMAKE_POSITION_INDEPENDENT_CODE=1 for cmake.
pycapnp has additional development dependencies, including cython and pytest. See requirements.txt for them all.
Building and installation
Install with pip install pycapnp. You can set the CC environment variable to control which compiler is used, ie CC=gcc-8.2 pip install pycapnp.
Or you can clone the repo like so:
git clone https://github.com/haata/pycapnp-async.git
cd pycapnp-async
pip install .If you wish to install using the latest upstream C++ Cap'n Proto:
pip install \
--install-option "--libcapnp-url" \
--install-option "https://github.com/sandstorm-io/capnproto/archive/master.tar.gz" \
--install-option "--force-bundled-libcapnp" .To force bundled python:
pip install --install-option "--force-bundled-libcapnp" .Python Versions
Python 3.7+ is supported. Earlier versions of Python have asyncio bugs that might be possible to work around, but may require significant work (3.5 and 3.6).
Development
Git flow has been abandoned, use master.
To test, use a pipenv (or install requirements.txt and run pytest manually).
pip install pipenv
pipenv install
pipenv run pytestBinary Packages
Building a dumb binary distribution:
python setup.py bdist_dumbBuilding a Python wheel distributiion:
python setup.py bdist_wheelPypi Upload Instructions
Only necessary if uploading release to pypi.org.
TODO
Documentation/Example
There is some basic documentation here.
The examples directory has one example that shows off pycapnp quite nicely. Here it is, reproduced:
from __future__ import print_function
import os
import capnp
import addressbook_capnp
def writeAddressBook(file):
addresses = addressbook_capnp.AddressBook.new_message()
people = addresses.init('people', 2)
alice = people[0]
alice.id = 123
alice.name = 'Alice'
alice.email = 'alice@example.com'
alicePhones = alice.init('phones', 1)
alicePhones[0].number = "555-1212"
alicePhones[0].type = 'mobile'
alice.employment.school = "MIT"
bob = people[1]
bob.id = 456
bob.name = 'Bob'
bob.email = 'bob@example.com'
bobPhones = bob.init('phones', 2)
bobPhones[0].number = "555-4567"
bobPhones[0].type = 'home'
bobPhones[1].number = "555-7654"
bobPhones[1].type = 'work'
bob.employment.unemployed = None
addresses.write(file)
def printAddressBook(file):
addresses = addressbook_capnp.AddressBook.read(file)
for person in addresses.people:
print(person.name, ':', person.email)
for phone in person.phones:
print(phone.type, ':', phone.number)
which = person.employment.which()
print(which)
if which == 'unemployed':
print('unemployed')
elif which == 'employer':
print('employer:', person.employment.employer)
elif which == 'school':
print('student at:', person.employment.school)
elif which == 'selfEmployed':
print('self employed')
print()
if __name__ == '__main__':
f = open('example', 'w')
writeAddressBook(f)
f = open('example', 'r')
printAddressBook(f)Also, pycapnp has gained RPC features that include pipelining and a promise style API. Refer to the calculator example in the examples directory for a much better demonstration:
import capnp
import socket
import test_capability_capnp
class Server(test_capability_capnp.TestInterface.Server):
def __init__(self, val=1):
self.val = val
def foo(self, i, j, **kwargs):
return str(i * 5 + self.val)
def server(write_end):
server = capnp.TwoPartyServer(write_end, bootstrap=Server(100))
def client(read_end):
client = capnp.TwoPartyClient(read_end)
cap = client.bootstrap()
cap = cap.cast_as(test_capability_capnp.TestInterface)
remote = cap.foo(i=5)
response = remote.wait()
assert response.x == '125'
if __name__ == '__main__':
read_end, write_end = socket.socketpair(socket.AF_UNIX)
# This is a toy example using socketpair.
# In real situations, you can use any socket.
server(write_end)
client(read_end)