Classes Vs. Functions [Closed]

Question

Functions are easy to understand even for someone without any programming experience, but with a fair math background. On the other hand, classes seem to be more difficult to grasp.

Let's say I want to make a class/function that calculates the age of a person given his/her birthday year and the current year. Should I create a class for this, or a function? Or is the choice dependant to the scenario?

P.S. I am working on Python, but I guess the question is generic.

Accepted Answer

Create a function. Functions do specific things, classes are specific things.

Classes often have methods, which are functions that are associated with a particular class, and do things associated with the thing that the class is - but if all you want is to do something, a function is all you need.

Essentially, a class is a way of grouping functions (as methods) and data (as properties) into a logical unit revolving around a certain kind of thing. If you don't need that grouping, there's no need to make a class.

Answer 2

Like what Amber says in her answer: create a function. In fact when you don't have to make classes if you have something like:

class Person(object):
    def __init__(self, arg1, arg2):
        self.arg1 = arg1
        self.arg2 = arg2

    def compute(self, other):
        """ Example of bad class design, don't care about the result """
        return self.arg1 + self.arg2 % other

Here you just have a function encapsulate in a class. This just make the code less readable and less efficient. In fact the function compute can be written just like this:

def compute(arg1, arg2, other):
     return arg1 + arg2 % other

You should use classes only if you have more than 1 function to it and if keep a internal state (with attributes) has sense. Otherwise, if you want to regroup functions, just create a module in a new .py file.

You might look this video (Youtube, about 30min), which explains my point. Jack Diederich shows why classes are evil in that case and why it's such a bad design, especially in things like API.
It's quite a long video but it's a must see.

Answer 3

i know it is a controversial topic, and likely i get burned now. but here are my thoughts.

For myself i figured that it is best to avoid classes as long as possible. If i need a complex datatype I use simple struct (C/C++), dict (python), JSON (js), or similar, i.e. no constructor, no class methods, no operator overloading, no inheritance, etc. When using class, you can get carried away by OOP itself (What Design pattern, what should be private, bla bla), and loose focus on the essential stuff you wanted to code in the first place.

If your project grows big and messy, then OOP starts to make sense because some sort of helicopter-view system architecture is needed. "function vs class" also depends on the task ahead of you.

Must Read

function

purpose: process data, manipulate data, create result sets.
when to use: always code a function if you want to do this: “y=f(x)”

Classes Vs. Functions [Closed]

8 Answers

Must Read

function

Chloe Bennett