[FIXED] python - should I use static methods or top-level functions

Issue

I come from a Java background and I'm new to python. I have a couple scripts that share some helper functions unique to the application related to reading and writing files. Some functions associated with reading, some with writing. While searching for the correct approach, I saw this: Static methods in Python?

He mentions in his answer:

Finally, use staticmethod sparingly! There are very few situations where static-methods are necessary in Python, and I've seen them used many times where a separate "top-level" function would have been clearer.

I don't understand top-level functions very well and I'm not sure given this simple example which is better: 1) create a class for a reader with static reader functions and the same for a writer or 2) to declare these helpers as global functions and why?

EDIT: REALLY good article about this subject i just found http://tomayko.com/writings/the-static-method-thing

Solution

In Java there's the (IMHO wrong) idea to use classes everywhere, even just group together static functions that don't share any state (and thus such classes will never be instantiated).

Python here begs to differ; if you have functions that don't have some shared state¹ (and thus in Java would typically be static functions) and aren't tightly related to a "real" class (=one that is actually instantiated) you just use free functions inside a module.

The reasoning behind this is that a class is needed only when you actually want to instantiate it, thus having a class just as a container for several functions that don't need to share an instance-specific state is useless.

Actually, you can somewhat think of a module as a static class - i.e. a container of functions (=static methods), module variables (=static fields) and types.

The nice thing in Python is that having top-level function doesn't give global namespace pollution problems, since in Python top-level functions/objects/... are still module-scoped. Thus, you can still group functions by module, without the unnecessary class-tax.

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1. actually, they can have some shared state, in form of module-level variables (so, singletons); again, the analogy modules-static classes seems to hold.

Answered By - Matteo Italia