Context variables in Python

Question

Suppose that I have a function in my Python application that define some kind of context - a user_id for example. This function call other functions that do not

Answer 1

You can use kwargs in your function calls in order to pass

def f1(user, operation):
    user_id = user.id
    # somehow define user_id as a global/context variable for any function call inside this scope
    f2(operation, user_id=user_id)

def f2(operation, **kwargs):
    # do something, not important, and then call another function
    f3(operation, **kwargs)

def f3(operation, **kwargs):
    # get user_id if there is a variable user_id in the context, get `None` otherwise
    user_id = kwargs.get("user_id")
    # do something with user_id and operation

the kwargs dict is the equivalent to what you are looking at in context variables, but limited at a call stack. It is the same memory element passed (through pointer-like) in each function and not duplicates variables in memory.

In my opinion, but I would like to see what you all think, context variables is an elegant way to authorize globals variables and to control it.