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#251: A 95% complete episode (wait for it)

Published Wed, Sep 22, 2021, recorded Wed, Sep 22, 2021

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Special guest: Brett Cannon

Michael #1: auto-optional

  • by Daan Luttik
  • Did you know that concrete types cannot be None in Python typing?
  • This is wrong:
        def do_a_thing(extra_info: str = None): ...
  • auto-optional will fix it:
        def do_a_thing(extra_info: Optional[str] = None): ...
  • Why would you want this?
  • Easily modify external libraries that didn't pay attention to proper use of optional to improve mypy linting.
  • Force consistency in your own code-base: Enforcing that None parameter implies an Optional type.
  • Run via the CLI: auto-optional [path]

Brian #2: Making World-Class Docs Takes Effort

  • Daniel Stenberg
  • Six requirements for a project to get a gold star
    • docs in the code repo
    • NOT extracted from the code
    • examples, lots of examples, more than you think you need
    • document every API call you provide
    • easily accessible and browsable
    • and hopefully offline readable as well
    • easy to contribute to
  • Non-stop iterating is key to having good docs.
  • extra goodness
    • consistency for section titles
    • cross-references
  • I’d add
    • Check for grammar and spelling mistakes
    • Consistency in all things, formatting, style, tone, depth of info of diff topics
    • Don’t be afraid to have a personality. docs that include easter eggs, fun examples, tasteful jokes, etc are nice, as long as that fun stuff doesn’t complicate the docs.
    • Don’t slam projects for having bad docs. Not all open source projects exist for your benefit.
      • You can make them better by contributing. :)

Brett #3: Starship

  • Continuing the trend of stuff to help make your coding better, Python or not. 😉
  • Also to make Michael’s new love of nerd fonts more useful. 😁
  • And more Rust on this show as Paul Everitt says I must do. 😉
  • Gives you a common shell prompt no matter which shell you use; I also find it easy to set up compared to most shells for their prompts
  • Lots of integrated support for various developer things such as printing what Python version you have when the directory has a pyproject.toml file.
  • Works nicely with the Python Launcher (as I mentioned the last time I was on).
  • Has some pyenv support that I don’t use. 😁

Michael #4: JMESPath

  • via Josh Thurston
  • Spent tons of time figuring out how to parse the pretty print results that had layers of nested dictionaries and lists. This module saved me time in a big way.
  • JMESPath (pronounced “james path”) allows you to declaratively specify how to extract elements from a JSON document.
  • For example, given this document:
        {"foo": {"bar": "baz"}}
  • The jmespath expression will return “baz”.
  • Even works with a projection-like result:
        {"foo": {"bar": [{"name": "one"}, {"name": "two"}]}}
  • The expression:[*].name will return ["one", "two"].
  • Negative indexing is also supported (-1 refers to the last element in the list).
  • Given the data above, the expression[-1].name will return "two".

Brian #5: pedalboard - audio effects library

  • from Spotify
  • The “power, speed, and sound quality of a DAW”, but in Python.
  • Introduction Article (warning: weird color changing header image that is painful to look at, so scroll past that quickly)
    • Built-in support for a number of basic audio transformations:
    • Convolution, Compressor, Chorus, Distortion
    • Gain, HighpassFilter, LadderFilter, Limiter, LowpassFilter
    • Phaser, Reverb

Brett #6: PEP 665 (and the journey so far)

  • Attempt to standardize lock files for Python.
  • Spent six months talking w/ folks privately to come up with the first public draft.
  • Initially a strict lock file, but Poetry and PDM feedback was platform-agnostic was important.
  • Proposal morphed to cover that.
  • Took it public and led to over 150 comments on Discourse.
  • People disliked it: from the title to the explanation to the proposed problem space to the actual solution.
  • Gone back to the drawing board privately w/ one of the original objectors participating; looking like we are reaching a good consensus on how to frame things and how it should ultimately look.
  • (Packaging) PEPs are hard.



  • Python is popular, apparently, and “on the verge of another big step forward” (another good place for dun, dun, duuunnn, ?)
    • "It only needs to bridge 0.16% to surpass C. This might happen any time now. If Python becomes number 1, a new milestone has been reached in the TIOBE index. Only 2 other languages have ever been leading the pack so far, i.e. C and Java."



Joke: Last 5%

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