apyio

Async wrappers for standard Python io streams.

Example Usage

For simple use cases this package provides the same high level utilities as the Python io module:

import apyio

string_buff = apyio.StringIO()
bytes_buff = apyio.BytesIO()
file_handle = apyio.open('somefile.txt', 'r')

The write, writelines, and close methods are left as normal functions just as they are for the asyncio streams. However, any function which might result in a read operation, such as read, readline, readlines, read1, seek, tell, and truncate, are now async def functions that must be `await`ed.

import apyio

async with apyio.open('somefile.txt', 'w') as file_handle:

    file_handle.write('some data')
    await file_handle.drain()  # Same as flush().

async with apyio.open('somefile.txt', 'r') as file_handle:

    data = await file_handle.read()
    print(data)

file_handle = apyio.open('somefile.txt', 'r')
async for line in file_handle:

    print(line)

For more advanced use cases, this package also contains async wrappers for all classes defined in the Python io module. The wrappers are named using the pattern Async<>Wrapper. For example, BufferedReader becomes AsyncBufferedReaderWrapper and FileIO becomes AsyncFileIOWrapper. All wrapper classes accept one argument in the constructor which must be the original, synchronous stream.

import io
import apyio

sync_stream = io.FileIO('somefile.txt', 'r')
async_stream = apyio.AsyncFileIOWrapper(sync_stream)
print(sync_stream.readline())
print((await async_stream.readline()))

If a file was opened using the built-in open() function it may not be an instance of io.FileIO. Depending on the options given to open() different kinds of streams may be returned. To help with wrapping arbitrary open() return values use the apyio.wrap_file() helper.

import apyio
file_handle = open('somefile.bin', 'r+b')
async_handle = apyio.wrap_file(file_handle)

Testing

All tests are stored in the '/tests' subdirectory. All tests are expected to pass for Python 3.5 and above. To run tests create a virtualenv and install the test-requirements.txt list. After that using the tox command will launch the test suite.

License

Copyright 2015 Kevin Conway

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Contributing

Firstly, if you're putting in a patch then thank you! Here are some tips for getting your patch merged:

Style

As long as the code passes the PEP8 and PyFlakes gates then the style is acceptable.

Docs

The PEP257 gate will check that all public methods have docstrings. If you're adding additional wrappers from the io module try to preserve the original docstrings if possible. If you're adding something new, like a helper function, try out the napoleon style of docstrings.

Tests

Make sure the patch passes all the tests. If you're adding a new feature don't forget to throw in a test or two. If you're fixing a bug then definitely add at least one test to prevent regressions.