Python

Contents:

• Async Python
  • Event loops and threads
  • Coroutines functions and objects
  • Awaitables
  • Waiting for multiple things
  • Doing things asynchronously but in order
  • Partials
  • How I might have designed this interface
  • Schedule normal code to run later
  • Multiple threads
• Asyncio (superseded by async page)
  • What is it
  • What good is it
  • Event loops
  • Coroutines
  • Futures
  • Tasks
  • Awaitables
  • Event loops
• Beautiful Soup
  • Intro
  • Tags and NavigableStrings
  • Navigating from some tag or the top of the document
• My Python Development Environment
  • Common requirements
  • Installing Python
  • Creating a virtualenv
  • Installing packages into the virtualenv
  • What about “tox”?
  • References and further reading
• Devpi
  • Uploading packages
• How to Fix your Python Code’s Style
  • Work from the repository root
  • Find files changed from a branch
  • Find files with uncommitted changes
  • Run flake8 on the changed files
  • Wrapping up
• Gitpython
• How Mock Can Improve Your Unit Tests
  • The mock methods and mock objects
  • Mock a function being called in another module
  • Mock an attribute
  • Mock something on a class
  • Where to mock
  • When we can’t mock
  • How mock.patch and mock.patch.object work
  • Controlling the mock object’s behavior
  • Determining what was done with a mock object
  • For more information
• Python Packaging
  • Source package
  • Wheels
  • Upload
  • Projects with code under a src directory
• Pip
• Pipenv
  • Pipenv documentation
  • Installing pipenv
  • Virtualenvs
  • Converting from a requirements file
  • Starting a new project
  • Creating a requirements file
  • Keeping dev-only packages out of production
• Better Python dependency management with pip-tools
  • My problems
  • Requirements
  • How to set it up
  • How to make the current virtual environment have the same packages and versions
  • How to update versions
  • Hash checking
  • What about pipenv?
  • Shortcomings
  • Conclusions
• Pyenv
• Six
• Timezones in Python
  • Key points
  • Some use cases
• Time zones and Daylight Saving Time—Oh, the Horror
  • Time zones
  • Daylight Saving Time
  • Practical advice on how to properly manage datetimes
  • Conclusion
• Tox
  • Command line
  • Configuration
  • Substitutions
  • Environment variables
• Python Versions
  • 3.11
  • 3.10
  • 3.9
  • 3.8
  • 3.7
  • 3.6
  • 3.5
  • 3.4
  • 3.3
  • 3.2
• Virtual environments
  • Using Python virtual environments
  • Virtualenv and virtualenvwrapper
• XML in Python
  • Formatting an etree Element

Most minimal logging

Python doesn’t provide any logging handlers by default, resulting in not seeing anything but an error from the logging package itself… Add a handler to the root logger so we can see the actual errors.:

import logging
logging.getLogger('').addHandler(logging.StreamHandler())

Binary data to file-like object (readable)

f = io.BytesIO(binary_data) # Python 2.7 and 3

Join list items that are not None

Special case use of filter:

join(', ', filter(None, the_list))

Declare file encoding

Top of .py file:

# -*- coding: UTF-8 -*-
# vim:fileencoding=UTF-8

Quick ‘n’ easy static web server

• Change to the top level directory of the static files

• Run python -m http.server

Python snippet copy logging to stdout

add to top:

import logging

handler = logging.StreamHandler()
root_logger = logging.getLogger('')
root_logger.setLevel(logging.DEBUG)
root_logger.addHandler(handler)

Warnings

Hiding python warnings. e.g. Deprecations:

python -Wignore::DeprecationWarning ...

Pylint

Running it:

python /usr/bin/pylint --rcfile=.pylintrc -f colorized aremind.apps.patients | less -r

Disabling a warning in code:

# pylint: disable-msg=E1101