#267: Python on the beach

Watch the live stream:

Play on YouTube

Watch the live stream replay

About the show

Sponsored by us:

• Check out the courses over at Talk Python
• And Brian’s book too!

Michael #1: Box: Python dictionaries with advanced dot notation access

• Want to treat dictionaries like classes? Box.

      small_box = Box({'data': 2, 'count': 5})
      small_box.data == \
          small_box['data'] == \
          getattr(small_box, 'data') == \
          small_box.get('data')
  

• There are over a half dozen ways to customize your Box and make it work for you: Check out the new Box github wiki for more details and examples!

• Superset of dict

• See Types of Boxes as well

Brian #2: Reading tracebacks in Python

• Trey Hunner
• “When Python encounters an error in your code, it will print out a traceback. Let's talk about how to use tracebacks to fix our code.”
• Brian’s commentary
  • Tracebacks can feel like brick wall of error telling you “you suck”.
  • But they are really meant to help you, and do, once you know how to read them.
  • Probably should be one of the earliest things we teach people new to coding. Like maybe:
    1. hello world
    2. tracebacks
    3. testing
  • Anyway, back to Trey
• Start at the bottom. Read the last line first
  • That will have the type of exception and an error message
• The two lines above that are
  • The exact filename and line number where the exception occurs
  • a copy of the line
• Those two lines are a stack frame.
• Keep going up and it’s other stack frames for the callstack of how you got here.
• Trey walks through this with an example and shows how to solve an error at a high level stack frame using the traceback.

Michael #3: Raspberry Pi: These two new devices just went live on the International Space Station

• The International Space Station has connected new Raspberry 4 Model B units to run experiments from 500 student programmer teams in Europe.
• From the education-focused European Astro Pi Challenge
• These are new space-hardened Raspberry Pi units, dubbed Astro Pi
• The AstroPi units are part of a project run by the European Space Agency (ESA) for the Earth-focused Mission Zero and Mission Space Lab.
• The former allows young Python programmers to take humidity readings on board ISS while the latter lets students run various scientific experiments on the space station using its sensors.

Brian #4: Make Simple Mocks With SimpleNamespace

• Adam Johnson
  • Who’s crushing it recently, BTW, lots of recent blog posts
• SimpleNamespace is in the types standard library package.
• Works great as a test double, especially as a stub or fake object.
• “It’s as simple as possible, with no faff around being callable, tracking usage, etc.”

• Example:

  >from types import SimpleNamespace
  >obj = SimpleNamespace(x=12, y=17, verbose=True)
  >obj
  namespace(x=12, y=17, verbose=True)
  >obj.x
  12
  >obj.verbose
  True
  

• unittest.mock.Mock also works, but has the annoying feature that, unless you pass in a spec, any attribute will be allowed.

• The SimpleNamespace solution doesn’t allow any typos or other attributes.
• Example:

  >obj.vrebose
  Traceback (most recent call last):
    File "[HTML_REMOVED]", line 1, in [HTML_REMOVED]
  AttributeError: 'types.SimpleNamespace' object has no attribute 'vrebose'. Did you mean: 'verbose'?
  

Michael #5: Extra, extra, exta

• Marak Squires, supply chain issues (NPM), and terrorism? [npm issues]
• css outlines!
• python 3.10.2
• Python Shorts YouTube series
  • #1 Parsing data with Pydantic
  • #2 Counting the number of times items appear with collections.Counter
• Stream Deck + PyCharm video, github repo

Brian #6: 3 Things You Might Not Know About Numbers in Python

• David Amos
• Most understated phrase I’ve read in a long time: “… there's a good chance that you've used a number in one of your programs”
• There’s more to numbers than many people realize
• The 3 things
  • numbers have methods
    • integers have
      • to_bytes(length=1, byteorder="big")
      • int.from_bytes(b'\x06\xc1', byteorder="big") class method
      • bit_length() and a bunch of others
    • floats have
      • is_integer(), as_integer_ratio()
      • and a bunch more
    • use variables or parentheses, though.
      • 5.bit_length() doesn’t work
      • n=5; n.bit_length() and (5).bit_length() works
  • numbers have hierarchy
    • Every number in Python is an instance of the Number class.
      • so isinstance(value, Number) should work for any number type
    • Then there’s 4 abstract types encompassing other types
      • Complex: has type complex
      • Real: has float
      • Rational: has Fraction
      • Integral: has int and bool
    • Where’s Decimal?
      • It’s not part of those abstract types, it directly inherits from Number
    • Also, floats are weird
  • Numbers are extensible
    • You can derive from numeric classes, both abstract and concrete, and create your own
    • However, to do this effectively, you gotta implement A LOT of dunder methods.

Joke: