Singleton design pattern (Two approaches). Taken a lot of help from internet examples.

Singleton.py

"""
@Author: Sujayyendhiren Ramarao
@Description: Singleton class. More than one approach.
"""

#Decorator approach

def singleton(class_):
    instances = {}

    def getinstance(*args, **kwargs):
        if class_ not in instances:
            instances[class_] = class_(*args,**kwargs)

        return instances[class_]

    return  getinstance

@singleton
class TestClass():
    def __init__(self, value):
        self.value = value

    def getValue(self):
        return self.value



#Approach 2:
#Metaclass

class Singleton( type ):
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super( Singleton, cls ).__call__(*args,**kwargs)
        return cls._instances[cls]

class MyClass():
    __metaclass__ = Singleton

    def __init__(self, value):
        self.value = value

    def getValue(self):
        return self.value


if __name__ == "__main__":
    """ Approach 1
    test1 = TestClass(200)
    test2 = TestClass(400)

    print(str(test1.getValue()))
    print(str(test2.getValue()))
    """

    """ Approach 2"""
    class1 = MyClass( "value1" )
    class2 = MyClass( "value2" )

    print(str(class2.getValue()))