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Episode #134: Python proves Mercury is the closest planet to Earth

Published Wed, Jun 12, 2019, recorded Mon, Jun 3, 2019.

Sponsored by DigitalOcean: pythonbytes.fm/digitalocean

Brian #1: Three scientists publish a paper proving that Mercury, not Venus, is the closest planet to Earth. using Python

  • contributed by, and explained by, listener Andrew Diederich.

    “This is from the March 19th, 2019 Strange Maps article. Which planet is, on average, closest to the Earth? Answer: Mercury. Actually, Mercury is, on average, the closest to all other planets, because it’s closest to the sun.”

  • article, including video, uses PyEphem, which apparently is now deprecated and largely replaced with skyfield.

Michael #2: Github semantics

  • Parsing, analyzing, and comparing source code across many languages
  • Written in a Haskell, it’s a library and command line tool for parsing, analyzing, and comparing source code.
  • It’s still early days yet, but semantic can do a lot of cool things, and is powering public-facing GitHub features. I’m tremendously excited as to see how it’ll evolve now that it’s a community-facing project.
  • Understands: Python, TypeScript, JavaScript, Ruby, Go, …
  • here are some cool things inside it:
    • A flow-sensitive, caching, generalized interpreter for imperative languages
    • An abstract interpreter that generates scope graphs for a given program text
    • A strategic rewriting system based on recursion schemes for open syntax terms

Brian #3: flake8-black

  • Contributed by Nathan Clayton
  • “The point of this plugin is to be able to run black --check ... from within the flake8 plugin ecosystem.”
  • I like to run flake8 during development both to keep things neat, and to train myself to just write code in a more standard way. This is a way to run black with no surprises.

Michael #4: Python Preview for VS Code

  • You write Python code (script style mostly), it creates an object-visualization
  • Think of a picture your first year C++ CS prof might draw. This extension does that automatically as you write Python code
  • Looks to be based (conceptually) on Philip Guo’s Python Tutor site.

Brian #5: Create and Publish a Python Package with Poetry

  • John Franey
  • Walks through creating a package, customizing the pyproject.toml, and talks about the different settings in the toml and what it means.
  • Then using the testpypi, and finally publish.

Michael #6: Pointers in Python: What's the Point?

  • by Logan Jones
  • Quick question: Does Python have pointers (outside of C-extensions, etc of course)?
  • Yet Python is more pointer heavy than most languages (more so than C# more so than even C++)!
  • In Python, everything is an object, even numbers and booleans.
  • Each object contains at least three pieces of data:
    • Reference count
    • Type
    • Value
  • Check that you have the same object is instead of ==
  • Python variables are pointers, just safe ones.
  • Interesting little tidbit from the article:
    • Interning strings is useful to gain a little performance on dictionary lookup—if the keys in a dictionary are interned, and the lookup key is interned, the key comparisons (after hashing) can be done by a pointer compare instead of a string compare. (Source)
  • But like we have inline-assembly in C++ and unsafe mode in C#, we can use pointers in Cython or more fine-grained with ctypes.

Extras

Michael:

  • PSF needs your help. Spread the word about the fundraiser and please, ask your company to contribute: Building the PSF: the Q2 2019 Fundraiser (Donations are tax-deductible for individuals and organizations that pay taxes in the United States)
    • “Contributions help fund workshops, conferences, pay meetup fees, support fiscal sponsorships, PyCon financial aid, and development sprints. ”

Jokes

via Jay Miller

What did the developer name his newborn boy? JSON


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