Classes Contain Methods

Sometimes we just want a collection of associated methods – think math.pi. In Python we could accomplish this by having a class that has no class or instance attributes and only static methods. Raymond Hettinger, a Python Language developer goes so far as to say the purpose of @staticmethod is to attach methods to classes1

So in Python a “bucket” of

class my_math:
    def pi():
        return 3.1416

    def circle_area(radius):
        return radius * radius * my_math.pi()

Here we have a static method that returns a value for π. This is my personal method for establishing a constant2. This avoids the situation where pi can be overwritten.

Python 3.9.10 (tags/v3.9.10:f2f3f53, Jan 17 2022, 15:14:21) [MSC v.1929 64 bit (AMD64)] on win32
>>> import math
>>> print(math.pi)
>>> print(math.sin(math.pi))
1.2246467991473532e-16  # essentially the correct answer (0.0) 
>>> math.pi =2.0
>>> print(math.sin(math.pi))
0.9092974268256817 # very much not zero

  1. Python Class Development Toolkit at↩︎

  2. Python has been described as a language for consenting adults–there is no privacy and there are no constants. Every value and method can be accessed changed by a determined programmer ↩︎