#28 The meaning of _ in Python

Brian #1: pep8.org : PEP 8 — the Style Guide for Python Code

• "This stylized presentation of the well-established PEP 8 was created by Kenneth Reitz (for humans)."
• From PEP 8: "This document gives coding conventions for the Python code comprising the standard library in the main Python distribution."
• PEP8 is not only used for the standard library. Many if not most open source Python packages adhere to at least most of the PEP8 recommendations
• testing plugins can help you make sure your code meets the guidelines (for good or bad).
• The pep8.org presentation is easy to read, with a left side clickable table of contents.
• Nice color coded examples. Green for good, Red for bad.
• links to specific items make it easy to share with others something specific.
• Good advice, but don't be a pep8-bully.

Michael #2: Tokio: Asyncio event loop written in Rust language

• Asyncio event loop written in Rust language
• It is still in alpha stage.
• It provides most of asyncio event loop apis, except udp.
• TCP api is more or less stable
• Aiohttp tests pass with tokio loop (~1800 tests)
• Mostly interesting as an example of Rust + Python
• Project is still in early stage of development

Brian #3: Python Boilerplate

• Interactive online tool for creating script and small project boilerplate code.
• Just starting, with "how to help" link.
• Select
  • Python 2 or 3
  • executable script or not
  • argparse
  • logging
  • .gitignore
  • Flask
  • unittest or pytest
  • tox
• fills in main.py, plus other files like test_sample.py, requirements.txt, tox.ini, etc.

Michael #4: Instagram switching to Python 3 on one branch

• Ancient Django but still productive
• Ran out of 32-bit user IDs before they ran out of Django power.
• Added sharing support to Django Orem
• Turned off GC for perf
• Upgraded entirely to 3.6 in a few months
• Why?
  • Type hints
  • Scaling server perf
  • asyncio
• Python 3 is where the future community work is happening
• Strategies
  • No user impact
  • Still shipping
  • Testing process was interesting
• This is a concrete roadmap for every large company

Brian #5: The Meaning of Underscores in Python

• single and double underscore meanings
• dunder is "double underscore"
  • Single Leading Underscore: _var
• method or variable for internal use
• convention only
• doesn't apply to collection.namedtuple
  • Single Trailing Underscore: var_
• used to avoid name collision with keywords
  • Double Leading Underscore: __var
• internal use by a single class level.
• Python will name mangle this so that subclasses don't have to avoid parent class double leading underscore names
  • Double Leading and Trailing Underscore: __var__
• no name mangling
• special names. dunder methods
• __call__ and __init__, etc.
  • Single Underscore: _
• in code : temp variable, don't care variable
• won't get a warning if you don't reference it again
• in REPL: last value

Michael #6: The future is looking bright for Python

• Stack Overflow recently released a cool new tool called Trends (previously covered)
• Check out the Most Popular Languages trend chart
• Python has, by a very large margin, the greatest positive slope (future?)
• And Py3 vs Py2