This document discusses modular programming in Python for ethical hackers. Modular programming breaks code into separate modules to make programs more readable, reliable, and maintainable. A module in Python is a file containing definitions and statements, and takes its name from the file name minus the .py extension. The document demonstrates creating a calculator module with add and sub functions, and importing and using those functions in a test program. It recommends several references for further reading on Python modules and programming.

1. Python for ethical hackers
Mohammad reza Kamalifard
kamalifard@datasec.ir

2. Python language essentials
Module 1:
Introduction to Python and Setting up an Environment for Programing
Part 6 :
Modular Programming

3. Modular Programming
• Develop programs which are readable, reliable and
•
•
•
•
maintainable without too much effort
Software design technique to split your code into separate
parts
The focus for this separation should be to have modules
with no or just few dependencies upon other modules
Minimization of dependencies is the goal
The executable application will be created by putting
separate module together.

4. Module in Python
• Module in Python is just a file containing Python definitions
and statements
• The module name is moulded out of the file name by
removing the suffix .py

5. Creating Module
$ vim calculator.py
#!/usr/bin/env python
'''
This is a simple calculator
add for addition
sub for subtraction
'''
def add(a, b):
return a+b
def sub(a, b):
return a-b
~
~

6. Creating Module
$ vim calculator.py
#!/usr/bin/env python
import calculator
print '2 + 3 is equal to : %d ' % calculator.add(2, 3)
print '10 - 3 is equal to : %d ' % calculator.sub(10, 3)
~
~
$ chmod a+x testcalc.py
$ ./testcalc.py
2 + 3 is equal to : 5
10 - 3 is equal to : 7

7. from … import
$ vim testcalc.py
#!/usr/bin/env python
from calculator import add
print '2 + 3 is equal to : %d ' % add(2, 3)
print '10 - 3 is equal to : %d ' % sub(10, 3)
~
$ ./testcalc.py
2 + 3 is equal to : 5
Traceback (most recent call last):
File "./testcalc.py", line 6, in <module>
print '10 - 3 is equal to : %d ' % sub(10,3)
NameError: name 'sub' is not defined

8. References
SPSE securitytube training by Vivek Ramachandran
SANS Python for Pentesters (SEC573)
Violent python
Security Power Tools
python-course.eu
----------------------------http://www.tutorialspoint.com/python/python_modules.htm
http://www.python-course.eu/modules_and_modular_programming.php

9. This work is licensed under the Creative Commons Attribution-NoDerivs 3.0 Unported License.
To view a copy of this license, visit
http://creativecommons.org/licenses/by-nd/3.0/
Copyright 2013 Mohammad Reza Kamalifard
All rights reserved.
Go to Kamalifard.ir/pysec101 to Download Slides and Course martials .