SIngleton from __defaults__

[Asaf Las]

On Wednesday, January 22, 2014 6:18:57 PM UTC+2, Chris Angelico wrote:
> On Thu, Jan 23, 2014 at 3:07 AM, Asaf Las <r... at gmail.com> wrote:
> ChrisA

and this one is about multiclass container function with 
multithreading support:

import threading

def provider(cls, x = [threading.Lock(), {}]):
    provider.__defaults__[0][0].acquire()
    if not cls.__name__ in provider.__defaults__[0][1]:
        provider.__defaults__[0][1][cls.__name__] = cls()
    provider.__defaults__[0][0].release()
    return provider.__defaults__[0][1][cls.__name__]


class whatever():
    def __init__(self):
        self.one = 1
        self.zero = 0

class whatever1():
    def __init__(self):
        self.one = 1
        self.zero = 0

    
print(id(provider(whatever)))
print(id(provider(whatever)))
print(id(provider(whatever1)))
print(id(provider(whatever1)))

could be there some hidden faults i missed? 

/Asaf