#348: JavaScript in Your Python

Published Tue, Aug 15, 2023, recorded Tue, Aug 15, 2023

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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

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 31for 20% discount (discount extended through the end of the month)
- 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:

Joke: Learning JavaScript

Full transcript