Python - Should I put my helper functions inside or outside the class?

python class pylint
Jack Z picture Jack Z · Oct 21, 2011 · Viewed 23.5k times · Source

In Python, if some methods of a class need a helper function, but the helper function itself doesn't use anything in the class, should I put the helper function inside or outside the class?

I tried putting it inside but PyLint was complaining that this function could have been put outside.

@Karl:

The class is a software upgrader and the helper function creates a new folder if the folder doesn't exist yet. The class is in a module having pretty much only the code for the class as of now. Other classes may be added later on.

Answer

Ethan Furman picture Ethan Furman · Oct 22, 2011

When deciding where to put helper functions the question I ask is, "Is it only for this class?" If it can help in other places, then it goes at the module level; if it is indeed only for this class, then it goes in the class with either staticmethod (needs no class data to do its job) or classmethod (uses some class, but not instance, data to do its job).

Another python code checker is pyflakes.

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