python-3.5 Archives

Using abc.ABCMeta in a way it is compatible both with Python 2.7 and Python 3.5

January 8, 2021 Andrew Rocky

Question or problem about Python programming: I’d like to create a class which has abc.ABCMeta as a metaclass and is compatible both with Python 2.7 and Python 3.5. Until now, I only succeeded doing this either on 2.7 or on 3.5 – but never on both versions simultaneously. Could someone give me a hand?

How to use async/await in Python 3.5?

January 7, 2021 Odhran Miss

Question or problem about Python programming: #!/usr/bin/env python3 # -*- coding: utf-8 -*- import time async def foo(): await time.sleep(1) foo() I couldn’t make this dead simple example to run: RuntimeWarning: coroutine ‘foo’ was never awaited foo() How to solve the problem: Solution 1: Running coroutines requires an event loop. Use the asyncio() library to […]

Type hints: solve circular dependency

January 7, 2021 Ollie MC

Question or problem about Python programming: The following produces NameError: name ‘Client’ is not defined. How can I solve it? class Server(): def register_client(self, client: Client) pass class Client(): def __init__(self, server: Server): server.register_client(self) How to solve the problem: Solution 1: You can use a forward reference by using a string name for the not-yet-defined […]

Python is a powerful general-purpose programming language.

Using List/Tuple/etc. from typing vs directly referring type as list/tuple/etc

January 7, 2021 Abreonia Ng

Question or problem about Python programming: What’s the difference of using List, Tuple, etc. from typing module:

How can I periodically execute a function with asyncio?

December 23, 2020 Abreonia Ng

Question or problem about Python programming: I’m migrating from tornado to asyncio, and I can’t find the asyncio equivalent of tornado’s PeriodicCallback. (A PeriodicCallback takes two arguments: the function to run and the number of milliseconds between calls.)

Functions Defined The core of extensible programming is defining functions. Python allows mandatory and optional arguments, keyword arguments, and even arbitrary argument lists.

Type hinting / annotation (PEP 484) for numpy.ndarray

December 18, 2020 Simon Abital

Question or problem about Python programming: Has anyone implemented type hinting for the specific numpy.ndarray class?

How to annotate types of multiple return values?

November 26, 2020 Oceane Wilson

Question or problem about Python programming: How do I use type hints to annotate a function that returns an Iterable that always yields two values: a bool and a str? The hint Tuple[bool, str] is close, except that it limits the return value type to a tuple, not a generator or other type of iterable.

Tag: python-3.5