#296: pip: Constrain your excitement

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Brian #1: Pip constraints files

• by luminousmen
• You can put some constraints on your dependencies with a constraints file.
• “Constraints files are requirements files that only control which version of a requirement is installed, not whether it is installed or not. “
• Syntax is a subset of requirements.txt syntax
  • but all the restrictions seem reasonable, considering
    • must have a name
    • can’t be editable
    • can’t specify extras (that one is maybe slightly weird)
• You can put --constraint constraints.txt right at the top of your requirements.txt file
• or specify it on command line,
  • pip install --constraint constraints.txt -r requirements.txt
• Or, my favorite, stick it at the top of requirements.in file.
  • yes. pip-compile correctly handles constraints when generating requirements.txt.
• Example
  • requirements.in --constraint constraints.txt typer
  • constraints.txt click<8.1.3
  • Output from pip-compile requirements.in

    #
    # This file is autogenerated by pip-compile with python 3.10
    # To update, run:
    #
    #    pip-compile requirements.in
    #
    click==8.1.2
        # via
        #   -c constraints.txt
        #   typer
    typer==0.6.1
        # via -r requirements.in
    

Michael #2: async-cache

• A caching solution for asyncio
• Quite simple but looks effective and flexible too
• Example:

  # TTL Cache
  from cache import AsyncTTL
  
  @AsyncTTL(time_to_live=60, maxsize=1024)
  async def func(*args, **kwargs):
      """
      time_to_live : max time for which a cached result  is valid
      maxsize : max number of results that are cached.
                  if  max limit  is reached the oldest result  is deleted.
      """
      pass
  

Brian #3: Organize Python code like a PRO

• Guilherme Latrova
• Yes, this is one author’s opinion. but…
  • lots of great advice
  • nothing too weird
  • no tool recommendations
• Recommendations of note
  • keep a src dir.
    • A cool and simple reason: it keeps your source code together in alphabetized IDEs.
  • file/module names: plural except for config, main, core, or similar
    • slightly weird tangent that there are no files, there are modules. ok, whatever.
    • Also talking about directories as main modules. odd. but ok.
  • functions/methods should be verbs
  • variables/constants should be nouns
  • Class names should be singular, unless the class really represents a container
  • The __name__ == "__main__" trick for modules.
  • The __main__.py entry point trick for modules/packages so that -m mymodule does something.
-

Michael #4: keyring

• via Trent
• The Python keyring library provides an easy way to access the system keyring service from python. It can be used in any application that needs safe password storage.
• It’s also helpful in that it allows you to write your own backends. Useful for testing.
• Basically create a dummy keychain that stores to a pytest temp_path fixture instead of cluttering the real keychain.
• You could potentially write a backend to interact with any service such as 1Password.

Extras

Brian:

• I’m taking a class on FastAPI. The instructor is awesome!
• Also, editing some pytest course video.

Michael:

• Gitlab, you alright??

Joke:

• from a dad-jokes repo
  • Q: How do programming pirates pass method parameters?
  • A: Varrrrarrrgs.
  • Q: How do you get the code for the bank vault?
  • A: You checkout their branch.
  • "Unfortunately these jokes only work if you git them."
• Screw driver