#348 JavaScript in Your Python

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• Michael: @mkennedy@fosstodon.org
• Brian: @brianokken@fosstodon.org
• Show: @pythonbytes@fosstodon.org

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Brian #1: Differentiating between writing down dependencies to use packages and for packages themselves

• Brett Cannon
• Why can’t we just use pyproject.toml and stop using requirements.txt?
• Nope. At least not yet. They’re currently for different things.
• pyproject.toml
  • There’s project.dependencies and project.optional-dependencies.tests that kinda would work for listing dependencies for an app.
  • But you can’t say pip install -r pyproject.toml. It doesn’t work. And that’s weird.
  • project is intended for packaged projects.
• requirements.txt
  • for applications and other non-packaged projects
  • It has specific versions
  • works great with pip
• What then?
  • Either we stick with requirements.txt
  • Or we invent some other file, maybe requirements.toml?
  • Or maybe (Brian’s comment), add something like [application] and application.dependencies and application.optional-dependencies.tests to pyproject.toml

Michael #2: PythonMonkey

• PythonMonkey is a Mozilla SpiderMonkey JavaScript engine embedded into the Python VM, using the Python engine to provide the JS host environment.
• This product is in an early stage, approximately 80% to MVP as of July 2023. It is under active development by Distributive. External contributions and feedback are welcome and encouraged.
• It will enable JavaScript libraries to be used seamlessly in Python code and vice versa — without any significant performance penalties.
• Call Python packages like NumPy from within a JavaScript library, or use NPM packages like [crypto-js](https://www.npmjs.com/package/crypto-js) directly from Python.
• Executing WebAssembly modules in Python becomes trivial using the WebAssembly API and engine from SpiderMonkey.
• More details in Will Pringle’s article.

Brian #3: Quirks of Python package versioning

• Seth Larson
• Yes, we have SemVer, 1.2.3, and CalVer, 2023.6.1, and suffixes for pre-release, 1.2.3pre1.
• But it gets way more fun than that, if you get creative
• Here’s a few
  • v is an optional prefix, like v.1.0
  • You can include an “Epoch” and separate it from the version with a !, like 20!1.2.3
  • Local versions with alphanumerics, periods, dashes, underscores, like 1.0.0+ubuntu-1. PyPI rejects those. That’s probably good.
  • Long versions. There’s no max length for a version number. How about 1.2.3.4000000000000000001?
  • Pre, post, dev aren’t mutually exclusive: 1.0.0-pre0-post0-dev0
  • More craziness in article
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Michael #4: bear-type

• Beartype is an open-source PEP-compliant near-real-time pure-Python runtime type-checker emphasizing efficiency, usability, and thrilling puns.

• Annotate @beartype-decorated classes and callables with type hints.

  • Call those callables with valid parameters: Transparent
  • Call those callables with invalid parameters: Boom

  Traceback: raise exception_cls( beartype.roar.BeartypeCallHintParamViolation: @beartyped quote_wiggum() parameter lines=[b'Oh, my God! A horrible plane crash!', b'Hey, everybody! Get a load of thi...'] violates type hint list[str], as list item 0 value b'Oh, my God! A horrible plane crash!' not str.

Extras

Brian:

• Python Testing with Pytest Course Bundle: Limited Pre-Release Beta
  • Use code PYTHONBYTES now through Aug 17 for 20% discount
  • What’s a pre-release beta? There’s a video. Check out the link.
• Error-tolerant pytest discovery in VSCode
  • Finally! But you gotta turn it on. Also, I gotta talk to them about the proper non-capitalization of pytest.
• We’re at RC1 for Python 3.12.0
  • Hard to believe it’s that time of year again

Michael:

• PyPI hires a Safety & Security Engineer, welcome Mike Fiedler
• PackagingCon October 26-28
• Cloud Builders: Python Conf (born in Ukraine): September 6, 2023 | online

Joke: Learning JavaScript