example of singleton design pattern in python

singleton.py

counter = 1

class TestSingleton:
	__instance = None
	__var = 0
	def __init__(self):
		global counter
		self.__var = counter
		counter += 1		

	def get_var(self):
		return self.__var

	@staticmethod
	def get_instance():
		if TestSingleton.__instance == None :
			TestSingleton.__instance = TestSingleton()
		return TestSingleton.__instance

t1 = TestSingleton.get_instance()
print id(t1), t1.get_var()

t2 = TestSingleton.get_instance()
print id(t2), t2.get_var()

t3 = TestSingleton.get_instance()
print id(t3), t3.get_var()