You can't have references to variables in Python. A variable is just a name, in some namespace (usually the __dict__ of a module, class, or instance object, or the special local namespace inside a function-call frame), for a value.
You can have references to values, but of course numbers are immutable values, so you can't change the number 1 into the number 2.
So, what you can do is create some kind of mutable value that holds the number, and share references to that.
One obvious possibility is to just give each Specific instance a reference to the General instance that created it:
class General():
def __init__(self):
self._shared_variable = 0
self._specific1 = Specific(self)
self._specific2 = Specific(self)
class Specific():
def __init__(self, shared_general):
self._shared_general = shared_general
def modify_shared_variable(self):
self._shared_general._shared_variable +=1
Another possibility is to store a single-element list:
class General():
def __init__(self):
self._shared_variable = [0]
self._specific1 = Specific(self._shared_variable)
self._specific2 = Specific(self._shared_variable)
class Specific():
def __init__(self, shared):
self._shared = shared
def modify_shared_variable(self):
self._shared[0] += 1
(This is really the same thing you're doing in C++, but without the syntactic sugar of arrays and pointers being nearly the same thing…)
Or you can create a simple MutableInteger class that holds an int, proxies non-mutating methods to it, adds a set method to replace it, and handles += and other mutating methods by calling set and returning self, instead of returning a new value.
