Effective Python Book Club

Owned by Cliff Dyer (Deactivated)
Last updated: Aug 28, 2018 by Nimisha Asthagiri (Deactivated)
3 min read

March 30, 2016: Chapters 1 & 2

Attending

Notes

  • Item 2:
    • double-underscore is not for private variables.
  • Item 3:
    • How to handle native strings?
      • from __future__ import unicode_literal & silence when needed (variable behavior between files (yuck))
      • lint native strings
      • have coercion functions
    • Needs engineering education
  • Item 5: slice
    • Is it bad that it is forgiving?
      • Sometimes it's useful
      • Maybe there should be a failfast version.
  • Item 10: enumerate
    • Very useful
    • Takes initial index!  Cool!
  • Item 11: zip
    • Makes Akiva nervous, because it has weird behavior with different length strings
    • zip_longest does the longer one (padding with Nones)
  • Item 12:
    • Renzo disagrees
    • should we avoid else blocks.
    • "If a feature is rare and somewhat surprising, you shouldn't use it." – Akiva
    • Alternative is good: break loop out into a separate function
    • Use with comment to describe behavior.
  • Item 14: Avoid None
    • not var is a source of bugs because None and 0 are both false
    • It's fairly useful for containers (lists, dicts, strings, etc.)
  • Item 15: Closures
    • Accessing non-locals: create a class
    • Use nonlocals as read only
  • Item 16: consider generators instead of lists
    • small lists are fine
    • generators can be problematic.  See Item 17.
    • we don't do much of this
    • generators are awesome
    • custom containers are awesomer
  • Item 17: be defensive when iterating over sequences twice.
    • iter(foo) is iter(foo)
      • different from iter(foo) is foo?
    • convert to list if you hit this kind of error and don't want to refactor into a custom container.
  • Item 21: keyword only args
    • Nimisha does not recommend using **kwargs to enforce keyword-only args, because it makes the code ugly and hard to read
      • Sometimes it's useful anyway

Not Discussed

  • Item 1: Know which version of Python you're using
  • Item 4: Write helper functions instead of complex expressions
  • Item 6: avoid using start, end, and stride in a single slice
    • I think we did discuss this, at least obliquely.  I didn't capture notes.
  • Item 7: Use list comprehensions instead of map and filter
  • Item 8: Avoid more than two expressions in list comprehensions
  • Item 9: Consider generator expressions for large comprehensions
  • Item 13: Take advantage of each block in try/except/else/finally
  • Item 18: Reduce visual noise with variable positional arguments
  • Item 19: Provide optional behavior with keyword arguments
  • Item 20: Use None and docstrings to specify dynamic default arguments

April 6, 2016 Notes: Chapter 3

Attending

Cliff Dyer (Deactivated) Eric Fischer (Deactivated)

Notes:

  • Item 26: Mixins
    • Good to see practice formalized
    • No __init__ was a new practice for us.  Would add cleanliness to some code.
  • Item 28: collections.abc
    • Fluently pythonic objects are great.  We should do more of them.  This makes it easy.


April 20, 2016 Notes: Chapter 5

Attending

Cliff Dyer (Deactivated) Eric Fischer (Deactivated) Ned Batchelder (Deactivated) Renzo Lucioni (Deactivated) Michael Katz (Deactivated) Nimisha Asthagiri (Deactivated) akivaR (Deactivated)

Notes

  • Coroutines: Confusing example.  What is the benefit?
    • Separates dumb client and smart server
    • Probably not the kind of thing we want to write in edX production code (probably)
  • concurrent.futures
    • Allows you to send data in chunks
  • When to use threads vs. concurrent.futures:
    • lower level – to implement different patterns of work.
  • subprocess doesn't let you interact with the called process.  Use pyexpect ( ?)
    • subprocess creates two threads to deal with I&O, 
  • LMS Grading has a five day timeout before getting hard-killed. 
    • This should be parallelizable.


April 27, 2016 Notes: Chapter 6

Attending: Eric Fischer (Deactivated) akivaR (Deactivated) Ned Batchelder (Deactivated) Sandy Student (Deactivated)

Notes

  • Fairly uncontroversial overall, good to know how these modules work
  • Addition from Ned: don't forget that __exit__() has a chance to look at thrown exception, it's not just a finally (self.assertRaises in unit tests)
  • Would have been nice to see an example of PyPI utilities, like https://pypi.python.org/pypi/arrow

May 4, 2016 Notes: Chapter 7 Collaboration

Attending: Eric Fischer (Deactivated) Renzo Lucioni (Deactivated) Cliff Dyer (Deactivated)

Notes:

  • None taken

May 4, 2016 Notes: Chapter 7 Collaboration

Attending: Cliff Dyer (Deactivated) Sandy Student (Deactivated) Eric Fischer (Deactivated) Michael Katz (Deactivated)

Notes:

  • Use a debugger (like pdb, Item 57).  Scott says so.
    • There are pdb alternatives rpdb, pydb, etc. that do remote debugging.
  • reprs are handy.  Create them when you need them, and include in your commit.
  • Profiling: Is there a graphical profiler?  SnakeViz seems to be the thing.