Borg Pattern

Oct 06, 2010

Singleton Design Patterns create all sorts of problems as you have exactly one instance for the singleton class throughout the program.

# Singleton implementation using new-style classes
class Singleton(object):
    def __new__(type):
        if not '_the_instance' in type.__dict__:
            type._the_instance = object.__new__(type)
        return type._the_instance

class Foo(Singleton):
    pass

>>> foo = Foo()
>>> bar = Foo()
>>> id(foo), id(bar)
(10049912, 10049912)

Usually programmers use Singleton Patterns as a global entry point ...