As described in python documentation, when python see some import statement it does the following things: checks some global table if module is already imported if module is not imported python imports it, creates module object and puts newly created module object to the global table if module is imported python just gets module object … Read more
You can install the wheel file for Python 3.4 here: First you have to install the wheel package from pip then install Pygame. pip install wheel pip install pygame‑1.9.2a0‑cp34‑none‑win_amd64.whl Here’s a video to help you install pip on Youtube.
data is the source of the list comprehension; it is the one parameter that is passed to the nested scope created. Everything in the list comprehension is run in a separate scope (as a function, basically), except for the iterable used for the left-most for loop. You can see this in the byte code: >>> … Read more
MySQLdb does not support Python 3 but it is not the only MySQL driver for Python. mysqlclient is essentially just a fork of MySQLdb with Python 3 support merged in (and a few other improvements). PyMySQL is a pure python MySQL driver, which means it is slower, but it does not require a compiled C … Read more
Update: As of Python 3.8, functools.singledispatchmethod allows single dispatch on methods, classmethods, abstractmethods, and staticmethods. For older Python versions, see the rest of this answer. Looking at the source for singledispatch, we can see that the decorator returns a function wrapper(), which selects a function to call from those registered based on the type of … Read more
There isn’t a hugely elegant way to handle import cycles in general, I’m afraid. Your choices are to either redesign your code to remove the cyclic dependency, or if it isn’t feasible, do something like this: # some_file.py from typing import TYPE_CHECKING if TYPE_CHECKING: from main import Main class MyObject(object): def func2(self, some_param: ‘Main’): … … Read more
The error is pretty clear. The file hello.py is not an executable file. You need to specify the executable: subprocess.call([‘python.exe’, ‘hello.py’, ‘htmlfilename.htm’]) You’ll need python.exe to be visible on the search path, or you could pass the full path to the executable file that is running the calling script: import sys subprocess.call([sys.executable, ‘hello.py’, ‘htmlfilename.htm’])
1. When and where to use enums? When you have a variable that takes one of a limited set of possible values. For example, the days of the week: class Weekday(Enum): MONDAY = 1 TUESDAY = 2 WEDNESDAY = 3 THURSDAY = 4 FRIDAY = 5 SATURDAY = 6 SUNDAY = 7 2. Why do … Read more
Installing libffi-dev and re-installing python3.7 fixed the problem for me. to cleanly build py 3.7 libffi-dev is required or else later stuff will fail If using RHEL/Fedora: yum install libffi-devel or sudo dnf install libffi-devel If using Debian/Ubuntu: sudo apt-get install libffi-dev
To use requests (or any other blocking libraries) with asyncio, you can use BaseEventLoop.run_in_executor to run a function in another thread and yield from it to get the result. For example: import asyncio import requests @asyncio.coroutine def main(): loop = asyncio.get_event_loop() future1 = loop.run_in_executor(None, requests.get, ‘http://www.google.com’) future2 = loop.run_in_executor(None, requests.get, ‘http://www.google.co.uk’) response1 = yield from … Read more