3.1.12. Programming Tips 1 Docstrings

  • Docstring tells you what the program does (interface) not how it does it.

  • Docstring is surrounded by three quotes, before and after Comments

  • Comments tells you how program does it (implementation)

  • Comments are preceded by a hash tag Example of Docstring and Comment

import math

def area_triangle_sss(side1, side2, side3):
    Returns area of a triangle, given the lengths of its three sides

    # Heron's formula
    semi_perim = (side1 + side2 + side3) / 2.0
    return math.sqrt(semi_perim *
                     (semi_perim - side1) *
                     (semi_perim - side2) *
                     (semi_perim - side3)) Example of Always Giving Conditional Output

  • Conditional Output should always be given if no criteria are met, i.e. always use else

def favourites(instructor):
    Returns the favourite thing of a given instructor

    if instructor == "Joe":
        return "games"
    elif instructor == "Scott":
        return "ties"
    elif instructor == "John":
        return "outdoors"
        print "Program saw invalid input:", instructor

print favourites("John")
print favourites("Jeannie")  #Returns None is there is no value
Program saw invalid input: Jeannie