Running coroutines requires an event loop. Use the asyncio() library to create one: import asyncio # Python 3.7+ asyncio.run(foo()) or # Python 3.6 and older loop = asyncio.get_event_loop() loop.run_until_complete(foo()) Also see the Tasks and Coroutines chapter of the asyncio documentation. If you already have a loop running, you’d want to run additional coroutines concurrently by … Read more
Most operating systems don’t support asynchronous file operations. That’s why asyncio doesn’t support them either. See the asyncio wiki for further explanation.
By default all your code is synchronous. You can make it asynchronous defining functions with async def and “calling” these functions with await. A More correct question would be “When should I write asynchronous code instead of synchronous?”. Answer is “When you can benefit from it”. In cases when you work with I/O operations as … Read more
You can use typing.IO, typing.TextIO, and typing.BinaryIO to represent different types of I/O streams. To quote the documentation: сlass typing.IO class typing.TextIO class typing.BinaryIO Generic type IO[AnyStr] and its subclasses TextIO(IO[str]) and BinaryIO(IO[bytes]) represent the types of I/O streams such as returned by open().
There are (sort of) two questions here: how can I run blocking code asynchronously within a coroutine how can I run multiple async tasks at the “same” time (as an aside: asyncio is single-threaded, so it is concurrent, but not truly parallel). Concurrent tasks can be created using the high-level asyncio.create_task or the low-level asyncio.ensure_future. … Read more
You could use six.add_metaclass or six.with_metaclass: import abc, six @six.add_metaclass(abc.ABCMeta) class SomeAbstractClass(): @abc.abstractmethod def do_something(self): pass six is a Python 2 and 3 compatibility library. You can install it by running pip install six or by downloading the latest version of six.py to your project directory. For those of you who prefer future over six, … Read more
The SIGSEGV signal indicates a “segmentation violation” or a “segfault”. More or less, this equates to a read or write of a memory address that’s not mapped in the process. This indicates a bug in your program. In a Python program, this is either a bug in the interpreter or in an extension module being … Read more
I had the same issue with Pycharm 2018.2 when working on a complex Flask project with SocketIO. When I put a debug breakpoint inside the code and pressed the debug button, it stopped at the breakpoint, but the variables didn’t load. It was just infinitely collecting data. I enabled Gevent compatibility and it resolved the … Read more
Upd: Starting with Python 3.6 we have asynchronous generators and able to use yield directly inside coroutines. import asyncio async def async_generator(): for i in range(3): await asyncio.sleep(1) yield i*i async def main(): async for i in async_generator(): print(i) loop = asyncio.get_event_loop() try: loop.run_until_complete(main()) finally: loop.run_until_complete(loop.shutdown_asyncgens()) # see: https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.shutdown_asyncgens loop.close() Old answer for Python 3.5: … Read more
As suggested by Josh Lee in the comment section, that kind of string interpolation was added in Python 3.6 only, see What’s New In Python 3.6 (here it’s called “PEP 498: Formatted string literals”). You, however, seems to be using Python 3.5.2, which does not support that syntax.