Class instance variable assigned inside function

Question

Can a class instance variable be set equal to a class instance variable of another class that was created inside a function? The code below seems to work (a.var = [5, []]) after the call to func() but I want to make sure that I am not missing anything:

def func():
  class C:
    def __init__(self):
      self.var = [[] for _ in np.arange(2)]
  c = C()
  c.var[0] = 5
  a.var = c.var

class A:
  def __init__(self):
    self.id = 0
    self.var = [[] for _ in np.arange(2)]

if __name__ == "__main__":
  a = A()
  func()

Answer 1

Yes, you're just assigning objects. Now, you should be very careful with the way you've written this. It's a bad idea to rely on the scope you have set out -- it will work, but I could easily see someone losing track of "a" and it never getting passed down to func(). A better implementation of func, in my opinion:

def func(a, val=5):
  class C:
    def __init__(self):
      self.var = [[] for _ in range(2)]
  c = C()
  c.var[0] = val
  a.var = c.var

class A:
  def __init__(self):
    self.id = 0
    self.var = [[] for _ in range(2)]

if __name__ == "__main__":
  a = A()
  func(a)
  aa = A()
  func(aa, val=10)

Since lists can contain any objects, you could do some even weirder stuff like.

aa.var[1] = a