pybetter 0.1.0

Tool for fixing trivial problems with your code.

pybetter

Tool for fixing trivial problems with your code.

Originally intended as an example for my PyCon Belarus 2020 talk about LibCST.

Usage

Simply provide a valid Python source code file as one of the argument and it will try to fix any issues it could find.

Usage: pybetter [OPTIONS] [SOURCES]...

Options:
  --noop  Do not make any changes to the source files.
  --help  Show this message and exit.

Example

# cat test.py
def f():
  return (42, "Hello, world")

# pybetter test.py
--> Processing 'test.py'...
  [+] (B003) Remove parentheses from the tuple in 'return' statement.
All done!

# cat test.py
def f():
  return 42, "Hello, world"

Available fixers

• B001: Replace 'not A in B' with 'A not in B'

  Usage of A not in B over not A in B is recommended both by Google and PEP-8. Both of those forms are compiled to the same bytecode, but second form has some potential of confusion for the reader.

  # BEFORE:
  if not 42 in counts:
    sys.exit(-1)
  
  # AFTER:
  if 42 not in counts:
    sys.exit(-1)
  

• B002: Default values for kwargs are mutable.

  As described in [Common Gotchas] (https://docs.python-guide.org/writing/gotchas/#mutable-default-arguments) section of "The Hitchhiker's Guide to Python", mutable arguments can be a tricky thing.

  This fixer replaces any default values that happen to be lists or dicts with None value, moving initialization from function definition into function body.

  # BEFORE
  def p(a=[]):
    print(a)
    
  # AFTER
  def p(a=None):
    if a is None:
      a = []
      
    print(a)
  

  Be warned, that this fix may break code which intentionally uses mutable default arguments (e.g. caching).

• B003: Remove parentheses from the tuple in 'return' statement.

  If you are returning a tuple from the function by implicitly constructing it, then additional parentheses around it are redundant.

  # BEFORE:
  def hello():
    return ("World", 42)
  
  # AFTER:
  def hello():
    return "World", 42
  

Installation

# pip install pybetter

Getting started with development

# git clone https://github.com/lensvol/pybetter
# poetry install

License

This project is licensed under the MIT License - see the LICENSE file for details

Authors

• Kirill Borisov ([e-mail])