What Is The Pythonic Way To Avoid Reference Before Assignment Errors In Enclosing Scopes?

I'm speaking about the general case. Here's an example: c = 1 def a(): def b(): print(c) b() c = 2 a() This code will return the following error: NameError: f

Solution 1:

Passing it as a parameter

When passing a outside variable as a parameter, avoid reusing names unless it's not possible that this variable can handle any other variable as parameter, then it doesn't really matter otherwise it will be confusing if you pass d the next time and you do operations on c within the function.

Secondly, the value ofcwill not get modified within the function even if changing name from param to c (it has very little meaning) when passing as a variable because it's not considered as a global varaible, even tho the variable is an object it will only be a object in this function unless you pass it into a class.

c = 1defa(param):
    defb():
        print(param)
    b()
    param = 2

a(c)

You would need to stick to the global option if you don't want to pass it as a parameter and you still want to affect c outside of your function. The global option will affect the "outside" c variable as your want it to.. but this is not really considered best practice, avid it if possible.

c = 1def a():
    global c
    def b():
        print(c)
    b()
    c = 2

a()

Here's what i would recommend:

c = 1defa(param):
    defb():
        print(param)
    b()
    param = 2return param

c = a(c)

Or even:

c = 1defb(param):
    print(param)
defa(param):
    b(param)
    param = 2return param

c = a(c)