Singleton in Python

singleton.py

class SingletonClass(object):
    def __new__(cls):
        if not cls._singleton:
            self = super(SingletonClass, cls).__new__(cls)

            # Real constructor
            self._init()

            cls._singleton = self

        return cls._singleton

    def _init(self):
        self.value = 42

# Call singleton

print SingletonClass().value
# > 42