#270: Can errors really be beautiful?

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About the show

Sponsored by Datadog: pythonbytes.fm/datadog

Special guest: Dean Langsam

Brian #1: A Better Pygame Mainloop

• Glyph
• Doing some game programming is a great way to work on coding for early devs (and experienced devs).
• pygame is a popular package for writing games in Python
• But… the normal example of a main loop, which listens for events and dispatches actions based on events, has some problems:
  • it’s got a while 1:
    • that wastes power, too much busy waiting
    • looks bad, due to “screen tearing” which is writing to a screen while your in the middle of drawing it
• This post discusses the problems, and walks through to an async main loop that creates a better gaming experience.

Michael #2: awesome sqlalchemy

• A few notable ones
• SQLAlchemy-Continuum: Versioning and auditing extension for SQLAlchemy.
• SQLAlchemy-Utc: SQLAlchemy type to store aware datetime.datetime values.
• SQLAlchemy-Utils: Various utility functions, new data types and helpers for SQLAlchemy
• filedepot: DEPOT is a framework for easily storing and serving files in web applications.
• SQLAlchemy-ImageAttach: SQLAlchemy-ImageAttach is a SQLAlchemy extension for attaching images to entity objects.
• SQLAlchemy-Searchable: Full-text searchable models for SQLAlchemy.
• sqlalchemy_schemadisplay: This module generates images from SQLAlchemy models.
• Can we also get a shoutout to SQLModel?

Dean #3: ThreadPoolExecutor in Python: The Complete Guide

• Long, but worth it (80-120 minutes). Could be consumed in parts. It’s mostly a collection of other blogposts on superfastpython
• Many examples
• LifeCycle
• Usage patterns
  • Map and was
  • as_completed vs sequentially
  • callbacks
• IO-Bound vs CPU-bound
• Common Questions
• Comparison
  • vs. ProcessPoolExecutor
  • vs. threading.Thread
  • vs. AsyncIO

Brian #4: Chaining comparison operators

• Rodrigo Girão Serrão
• I use chained expressions all the time, mostly with ranges:
  • min <= x <= max, which is like (min <=x) and (x <= max)
• There are lots of chained expressions available, and some not so obvious.
• a == b == c
  • all are equal, no prob
• what abut a != b != c ?
  • This actually can return True if a == c
• Lots of other issues with chaining discussed in the article, like non-constant expressions and side effects

Michael #5: Create Beautiful Tracebacks with Python’s Exception Hooks

    def exception_hook(exc_type, exc_value, tb):
        ...

    sys.excepthook = exception_hook

• Libraries
• rich.traceback
• better-exceptions
• Pretty Errors
• IPython.core.ultratb
• stackprinter

Dean#6: Ways I Use Testing as a Data Scientist

• The importance of knowing what to test for
• using assert in code on ad-hoc things. Do it while coding.
• Us numpy np.isclose to test “almost equal” on entire arrays. also [assert_frame_equal](https://pandas.pydata.org/docs/reference/api/pandas.testing.assert_frame_equal.html)
• Use hypothesis for bombarding the function with smart tests.
• Pandera and Great Expectations
• tests are documentation!
• Work with Arrange-Act-Assert
• Even if we’re not sure what to assert, writing a test that executes the code is still valuable.

Extras

Dean:

• Deprecate urllib out of stdlib?
• IPython 8 is out
  • It’s less code!
    • 37,500 LOC across 348 files → 36,100 across 294 files “I’m sorry I wrote you such a long letter. I didn’t have time to write you a short one.” – Blaise Pascal
  • This was all done thanks to a developer hired through Small Development Grants
  • coloring exceptions

Michael:

• Python Shorts New videos
  • Beyond the List Comprehension
  • Combining dictionaries, the Python 3.10 way
• / on pypi.org

Joke: Spelling