Question

My program needs to do 2 things.

1. Extract stuff from a webpage.

2. Do stuff with a webpage.

However, there are many webpages, such as Twitter and Facebook.

should I do this?

def facebookExtract():
    code here
def twitterExtract():
    code here
def myspaceExtract():
    code here
def facebookProcess():
    code here
def twitterProcess():
    code here
def myspaceProcess():
    code here

Or, should I have some sort of class? When is it recommended to use classes, and when is it recommend to just use functions?

Answer 1

My favorite rule of thumb: if you’re in doubt (unspoken assumption: “and you’re a reasonable person rather than a fanatic”;-), make and use some classes. I’ve often found myself refactoring code originally written as simple functions into classes — for example, any time the simple functions’ best way to communicating with each others is with globals, that’s a code smell, a strong hint that the system’s factoring is not really good — and often refactoring the OOP way is a reasonable fix for that.

Python is multi-paradigm, but its central paradigm is OOP (much like, say, C++). When a procedural or functional approach (maybe through generators &c) is optimal for some part of the system, that generally stands out — for example, static functions are also a code smell, and if your classes have any substantial amount of those THAT is a hint to refactor things to avoid that requirement.

So, assuming you have a rich grasp of all the paradigms Python affords — if you’re STILL in doubt, that suggests you probably want to go OOP for that part of your system! Just because Python supports OOP even more wholly than it supports functional programming and the like.

From your very skeletal code, it seems to me that each extract/process pair belongs together and probably needs to communicate state, so a small set of classes with extraction and processing methods seems a natural fit.