gistfile1.py

import copy

class MyClass(object):
    def __init__(self, x):
        self.x = x
        
    def __getattr__(self, name):
        if name == 'plus_one':
            newself = copy.copy(self)
            newself.x += 1
            return newself

a = MyClass(1)
print a.x

b = a.plus_one
print b.x, a.x

#    
# Traceback (most recent call last):
#  File "dev.py", line 16, in <module>
#    b = a.plus_one
#  File "dev.py", line 9, in __getattr__
#    newself = copy.copy(self)
#  File "/usr/lib/python2.7/copy.py", line 88, in copy
#    rv = reductor(2)
#TypeError: 'NoneType' object is not callable
#