In such a case I would use a method to set the boolean. So that you never set the boolean instance variable from outside directly, but call a method to change it. And in case you want to hide, that in fact a method is used, you can define it as a property. This would look like:
class MyClass:
# prefix the instance variables with an underscore
# as a convention to indicate they are private
_a = False
_b = [0,1,2]
# define accessors
@property
def a(self):
return self._a
@a.setter
def a(self, bool):
self._a= bool
if bool is True:
self._b= [0,1,2,3,4,5]
else:
self._b= [0,1,2]
# define accessors
@property
def b(self):
return self._b
Now we can test this:
o= MyClass()
print(f'{o._a}, {o._b}')
o.a=True
print(f'{o._a}, {o._b}')
o.a=False
print(f'{o._a}, {o._b}')
print(o.b)
o.b=[12,3]
This prints:
False, [0, 1, 2]
True, [0, 1, 2, 3, 4, 5]
False, [0, 1, 2]
[0, 1, 2]
Traceback (most recent call last):
File "<ipython-input-14-1e243ad0d3ed>", line 8, in <module>
o.b=[12,3]
AttributeError: can't set attribute
So you can see, that indeed the content of _b was changed, when a bool was assigned via o.a= and also, that you access the value of o._b by using the property o.b, but you can't set it via o.b=. This is just because I have not defined the setter. If you like to have one, you would have to define a function for it, just like in the setter of a.
If you define it this way, you should follow the convention, that you do not access the real instance variables _a and _b anywhere outside class MyClass in your code.
aandbto be instance attributes or class attributes? Hope you're aware of the difference.