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SUMMARY:Sentinel Values in Python: Why None Is Not Enough - Florian Wilhel
 m
DTSTART;TZID=Europe/Zurich:20261022T113500
DTEND;TZID=Europe/Zurich:20261022T120500
DTSTAMP:20261111T040115Z
UID:pretalx-swiss-python-summit-2026-JHJ3XY@talks.python-summit.ch
DESCRIPTION:Every Python developer has used `None` as a default but what h
 appens when `None` is also a valid value? This talk explores sentinel valu
 es as a first-class concept in Python. We'll uncover why `None` is semanti
 cally overloaded\, how built-in sentinels like `NotImplemented` and `...` 
 (Ellipsis) quietly power Python's object model\, and what happens when you
  try to create your own. The central challenge: Python's type system has n
 o good answer for sentinel values. We'll walk through why `Optional`\, `Li
 teral`\, and custom classes all fall short\, look at real-world workaround
 s including Pydantic's experimental MISSING\, and discuss what PEP 661's d
 eferral means for your code today. You'll leave with a clear mental model 
 and practical guidance for handling absence in typed Python.
LOCATION:Aula 4.101
URL:https://talks.python-summit.ch/swiss-python-summit-2026/talk/JHJ3XY/
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