Docstrings to provide information about class module functions and methods in Python

We can provide documentation to Modules, functions , class and methods by using docstrings.

Docstrings for documentation about functions, methods , class and modules in Python using formats

Documentation of functions

We can include details about the function for user understanding by writing some text about the function. This we can do by using three single quotes or by using three double quotes. It should be just after the function declaration.

def my_add(x,y):
    '''Takes two inputs and returns the sum'''
    return x+y
print(my_add(5,7)) #12 
print(my_add.__doc__)

By using __doc__ we are getting the output for second print command.

Takes two inputs and returns the sum

We should include about the functions, arguments, return value, error if any and additional notes in our Docstrings. Here is one sample.

def my_add(x,y):
    """ Adds to inputs 
    Args:
      x (int) : first integer to be addded
      y (int) : second integer to be added
    Raises:
      TypeError: can only concatenate str (not "int") to str
    Returns:
      Sum of two inputs.
    Notes:
      Visit www.plus2net.com for more info
    """
    return x+y
print(my_add.__doc__)

Documentation of class and methods

Here both class and method have the docstrings which can be retrived by using __doc__ .
Read more about class & Objects

class my_tutorial():
  '''This is about the tutorial to learn the language.'''  
  my_subject='Python'  # class attributes 
  #instance attributes
  def __init__(self,name,mark):
       self.name= name
       self.mark= mark
  def discount(self):
     '''This is about the discount offers.''' 
     if(self.mark > 50):
       return "Discount is avilable"
     else:
       return "No Discount"
Alex=my_tutorial('Alex',40)  # object is defined 
print(Alex.discount())    # No Discount # Discount method is used 
print(Alex.my_subject)    # Python # Class attribute is used
print(my_tutorial.__doc__)
print(my_tutorial.discount.__doc__)
#using the object
print(Alex.__doc__)
print(Alex.discount.__doc__)

Output is here

No Discount
Python
This is about the tutorial to learn the language.
This is about the discount offers.
This is about the tutorial to learn the language.
This is about the discount offers.

Documentation of modules

We will create one module like this and give the name my_module.py

'''This is module level docstrings'''
class my_tutorial():
  '''This is about the tutorial to learn the language.'''  
  my_subject='Python'  # class attributes 
  #instance attributes
  def __init__(self,name,mark):
       self.name= name
       self.mark= mark
  def discount(self):
     '''This is about the discount offers.''' 
     if(self.mark > 50):
       return "Discount is avilable"
     else:
       return "No Discount"

This module my_module.py we will import and print the docstrings of module, class and object. Our file docstrings_model.py is here

import my_module
print(my_module.__doc__)
print(my_module.my_tutorial.__doc__)
print(my_module.my_tutorial.discount.__doc__)

Output is here

This is module level docstrings
This is about the tutorial to learn the language.
This is about the discount offers.

Using help()

help('my_module')

About help()

Multiline docstrings

def my_add(x,y):
    '''Takes two inputs
     and returns
      the sum of the inputs.'''
    return x+y
#print(my_add(5,7)) #12 
print(my_add.__doc__)

Using double quotes for docstrings.

    """Takes two inputs
     and returns
      the sum of the inputs."""

Docstrings of modules

We can read the documentation of popular libraries we use. For Pandas library here is the code.

import pandas as pd
print(pd.__doc__)

For tkinter

import tkinter as tk
print(tk.__doc__)

Using colab

If you are working on Colab then the Jupiter Notebook has to be managed to import the library.
Mount the drive first

from google.colab import drive
drive.mount('/content/drive') #, force_remount=True

Change to the working directory

%cd /content/drive/MyDrive/Colab Notebooks/ 
!ls # listing of files

Import the module ( my_module.ipynb file here )

You may have to pip install import_ipynb before using .ipynb file as module.

import import_ipynb
import my_module
print(my_module.__doc__)
print(my_module.my_tutorial.__doc__)
print(my_module.my_tutorial.discount.__doc__)

Output is here.

This is module level docstring
This is about the tutorial to learn the language 
This is about the discount offers.

Global, local and non-local variables Builtin Functions

All String methods list Python- Tutorials

Subhendu Mohapatra

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Docstrings in Python