Docstrings

Écrire des fonctions en Python

Shayne Miel

Software Architect @ Duo Security

Une fonction complexe

def split_and_stack(df, new_names):
  half = int(len(df.columns) / 2)
  left = df.iloc[:, :half]
  right = df.iloc[:, half:]
  return pd.DataFrame(
    data=np.vstack([left.values, right.values]),
    columns=new_names
  )

def split_and_stack(df, new_names):
  """Split a DataFrame's columns into two halves and then stack
  them vertically, returning a new DataFrame with `new_names` as the
  column names.

  Args:
    df (DataFrame): The DataFrame to split.
    new_names (iterable of str): The column names for the new DataFrame.

  Returns:
    DataFrame
  """
  half = int(len(df.columns) / 2)
  left = df.iloc[:, :half]
  right = df.iloc[:, half:]
  return pd.DataFrame(
    data=np.vstack([left.values, right.values]),
    columns=new_names
  )

Anatomie d'une docstring

def function_name(arguments):
  """
  Description of what the function does.

  Description of the arguments, if any.

  Description of the return value(s), if any.

  Description of errors raised, if any.

  Optional extra notes or examples of usage.
  """

Formats Docstring

Style Google
Numpydoc
reStructuredText
EpyText

Style Google - description

def function(arg_1, arg_2=42):
  """Description of what the function does.
  """

Style Google - arguments

def function(arg_1, arg_2=42):
  """Description of what the function does.

  Args:
    arg_1 (str): Description of arg_1 that can break onto the next line
      if needed.
    arg_2 (int, optional): Write optional when an argument has a default
      value.
  """

Style Google - valeur(s) de retour

def function(arg_1, arg_2=42):
  """Description of what the function does.

  Args:
    arg_1 (str): Description of arg_1 that can break onto the next line
      if needed.
    arg_2 (int, optional): Write optional when an argument has a default
      value.

  Returns:
    bool: Optional description of the return value
    Extra lines are not indented.
  """

def function(arg_1, arg_2=42):
  """Description of what the function does.

  Args:
    arg_1 (str): Description of arg_1 that can break onto the next line
      if needed.
    arg_2 (int, optional): Write optional when an argument has a default
      value.

  Returns:
    bool: Optional description of the return value
    Extra lines are not indented.

  Raises:
    ValueError: Include any error types that the function intentionally
      raises.

  Notes:
    See https://www.datacamp.com/community/tutorials/docstrings-python
    for more info.  
  """

Numpydoc

def function(arg_1, arg_2=42):
  """
  Description of what the function does.

  Parameters
  ----------
  arg_1 : expected type of arg_1
    Description of arg_1.
  arg_2 : int, optional
    Write optional when an argument has a default value.
    Default=42.

  Returns
  -------
  The type of the return value
    Can include a description of the return value. 
    Replace "Returns" with "Yields" if this function is a generator.
  """

Récupération des docstrings

def the_answer():
  """Return the answer to life, 
  the universe, and everything.

  Returns:
    int
  """
  return 42

print(the_answer.__doc__)

Return the answer to life, 
  the universe, and everything.

  Returns:
    int

import inspect
print(inspect.getdoc(the_answer))

Return the answer to life, 
the universe, and everything.

Returns:
  int

Passons à la pratique !

Écrire des fonctions en Python