2020-11-02.md

ASWF Python 3 Working Group Meeting - 2020/10/19

Attendees

• Ashley Whetter, Chairperson, DNEG
• JT Nelson, Pasadena Python
• Alex Wilke, Animal Logic
• Narendra Vadapalli
• Robert Vinluan, SideFX
• David Aguilar, Disney Animation

Action Items

• Curate the guidelines docs w.r.t. the Futurize docs and the Conservative Python Porting Guide to call out differences. Review these docs, compare, contrast, summarize.

Agenda

• Notetaker: David Aguilar
• Review action points from last meeting
  • Find list of What’s new & what’s going away in 3.9 JT Nelson
• PR Review
  • Meeting notes template by JT Nelson
  • Autodesk statement by Martin de Lasa
  • Has a requested change on it
• Any blockers
• Ashley Whetter - Has anyone noticed segfaults on exit with PySide 2 and Python 3?
• David Aguilar - New Python 2/3 coding guidelines
• Additional items

Notes

• Alex Wilke new attendee from Animal Logic, welcome!

• Wanting to find list of what's going away in Python 3.9.

  • JT will add to repo notes.

• No new blockers for Python 3

• PySide2 / PyQt / Qt 5.12 crashes on exit -- Ashley brought this up w/ PySide2.

  • David -- yes, we have seen PyQt and pure-Qt apps crashing on exit in 5.12.
  • Possible cause is latent application code that relied on incorrect semantics, and newer versions of Qt are being more strict/"correct" in how they handle widget destruction.
  • Related Links
  • https://stackoverflow.com/questions/59120337/why-does-pyqt-sometimes-crash-on-exit/59126660#59126660
  • https://www.riverbankcomputing.com/static/Docs/PyQt5/gotchas.html#crashes-on-exit
  • https://doc.qt.io/qt-5/objecttrees.html#construction-destruction-order-of-qobjects
  • https://bugreports.qt.io/browse/QTBUG-71545
  • https://bugreports.qt.io/browse/QTBUG-63945 (interesting notes, maybe not related)

• Python Guidelines. We'll discuss items, drop style notes, and look at migrating them to the best practices document.

• Python3 Document

  • Note about implicit namespaces should be included.
  • shebang lines -- usually only using "python" in shebang lines. "python" still being used to imply python2+3 compatible. "If you only have environments that are a single version of Python then always use python. Only if you have a single version of Python (3) then should the shebang line say python3".
  • Absolute imports -- downside is having to remove the __future__ statements in the future. We should include.
  • Should call out futurize and python3 conservative porting guide as reference documents.