Style Guidelines

Python Code

• Generally follow Python’s PEP 8 style guidelines. We run the pep8 command to verify this during unittest runs.

• Break up logical blocks of related code with a newline. Specifically add a blank newline after conditional or looping blocks.

• Don’t comment what is obvious. Instead prefer meaningful names of functions and variables:

  # Get the functions signal annotations <-- this comment is unnecessary
  return_type, arg_types = get_signal_annotations(func)
  

• Use comments to explain non-obvious blocks and conditionals, magic, workarounds (with bug references), or generally complex pieces of code. Good examples:

  # If a property was defined with a decorator, it may already have
  # a name; if it was defined with an assignment (prop = Property(...))
  # we set the property's name to the member name
  if not prop.name:
      prop.name = name
  

  # Python causes MRO's to be calculated starting with the lowest
  # base class and working towards the descendant, storing the result
  # in __mro__ at each point. Therefore at this point we know that
  # we already have our base class MRO's available to us, there is
  # no need for us to (re)calculate them.
  if hasattr(base, '__mro__'):
      bases_of_subclasses += [list(base.__mro__)]
  

Python Doc Strings

• Doc strings should generally follow PEP 257 unless noted here.

• Use reStructuredText (reST) annotations.

• Use three double quotes for doc strings (""").

• Use a brief description on the same line as the triple quote.

• Include function parameter documentation (including types, returns, and raises) between the brief description and the full description. Use a newline with indentation for the parameters descriptions.

  def spam(amount):
      """Creates a Spam object with the given amount.
  
      :param int amount:
          The amount of spam.
      :returns:
          A new Spam instance with the given amount set.
      :rtype: Spam
      :raises ValueError:
          If amount is not a numeric type.
  
      More complete description.
      """
  

• For class documentation, use the classes doc string for an explanation of what the class is used for and how it works, including Python examples. Include __init__ argument documentation after the brief description in the classes doc string. The class __init__ should generally be the first method defined in a class putting it as close as possible (location wise) to the class documentation.

  class Bacon(CookedFood):
      """Bacon is a breakfast food.
  
      :param CookingType cooking_type:
          Enum for the type of cooking to use.
      :param float cooking_time:
          Amount of time used to cook the Bacon in minutes.
  
      Use Bacon in combination with other breakfast foods for
      a complete breakfast. For example, combine Bacon with
      other items in a list to make a breakfast:
  
      .. code-block:: python
  
          breakfast = [Bacon(), Spam(), Spam(), Eggs()]
  
      """
      def __init__(self, cooking_type=CookingType.BAKE, cooking_time=15.0):
          super(Bacon, self).__init__(cooking_type, cooking_time)