Counting instances of a class?

Question

I\'ve been cleaning up some code from a module I\'m extending and I can\'t seem to find a way to Pythonify this code:

global_next_id = 1

class Obj:
  def __         


        

Answer 1

Here is a way to count instances without descendant classes sharing the same id/count. A metaclass is used to create a separate id counter for each class.

Uses Python 3 syntax for Metaclasses.

import itertools

class InstanceCounterMeta(type):
    """ Metaclass to make instance counter not share count with descendants
    """
    def __init__(cls, name, bases, attrs):
        super().__init__(name, bases, attrs)
        cls._ids = itertools.count(1)

class InstanceCounter(object, metaclass=InstanceCounterMeta):
    """ Mixin to add automatic ID generation
    """
    def __init__(self):
        self.id = next(self.__class__._ids)