varname_hack.py

import itertools


def name_func(var, scope=globals):
    try:
        return itertools.ifilter(
        	lambda x: var is scope().get(x),
        	scope().keys()
    	).next()
    except StopIteration:
        return None


class NamedVar(type):

    def __new__(meta, name, bases, dct):
        dct['__varname__'] = property(name_func)
        return type.__new__(meta, name, bases, dct)


class A(object):

	__metaclass__ = NamedVar

	def __init__(self, v=0):
		self._val = v

	def __repr__(self):
		return '{var}: {val}'.format(
			var=self.__varname__,
			val=self._val
		)


if __name__ == '__main__':
	a = A()
	b = A(1)
	c = A(1)
	print (a, b, c)