Type Singleton

source code

object --+    
         |    
      type --+
             |
            Singleton

Singleton metaclass. To make a class instance a singleton, use this class
as your class's metaclass as follows:

class MyClass(object):
    __metaclass__ = Singleton

Singletons are created by passing the exact same arguments to the
constructor. For example:

class T():
    __metaclass__ = Singleton
    
    def __init__(self, value=None):
        self.value = value
    
t1 = T()
t2 = T()
t1 is t2
True
t3 = T(5)
t4 = T(5)
t3 is t4
True
t1 is t3
False