[issue18352] collections.Counter with added attributes are not deepcopied properly.

2013-07-03 Thread Olivier Gagnon 

New submission from Olivier Gagnon:

The following code shows that the Counter is not deepcopied properly. The 
same code with an user defined class or a dict is copied with the "b" attribute.

import collections
import copy

count = collections.Counter()
count.b = 3
print(count.b) # prints 3

count_copy = copy.deepcopy(count)
print(count_copy.b) # raise AttributeError: 'Counter' object has no attribute 
'b'

--
components: Library (Lib)
messages: 192239
nosy: Olivier.Gagnon
priority: normal
severity: normal
status: open
title: collections.Counter with added attributes are not deepcopied properly.
type: behavior
versions: Python 3.3

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[issue18352] collections.Counter with added attributes are not deepcopied properly.

2013-07-10 Thread Olivier Gagnon 

Olivier Gagnon added the comment:

The dictionary and the set do not give the freedom to add dynamic attributes to 
them. I agree that the Counter should have the same behaviour.

However, this will raise the same bug when we inherit from a Counter object.

>>> class mylist(list): pass
... 
>>> l = mylist()
>>> l.foo = "bar"
>>> c = copy.deepcopy(l)
>>> print(c.foo) # prints bar

>>> class myCounter(Counter): pass
... 
>>> original = myCounter()
>>> original.foo = "bar"
>>> c = copy.deepcopy(original)
>>> c.foo
Traceback (most recent call last):
  File "", line 1, in 
AttributeError: 'myCounter' object has no attribute 'foo'

The reduction function should still copy every dynamic attribute of the object.

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[issue18352] collections.Counter with added attributes are not deepcopied properly.

2013-07-12 Thread Olivier Gagnon 

Olivier Gagnon added the comment:

I can understand that the current behaviour can be correct in regard with the 
added attributes of the object. However, should I open a new issue for the 
following inheritance behaviour which the reduce function affects also.

class myCounter(Counter):
def __init__(self, bar, *args):
self.foo = bar
super().__init__(*args)

class myDict(dict):
def __init__(self, bar, *args):
self.foo = bar
super().__init__(*args)

c = myCounter("bar")
l = myDict("bar")
print(c.foo) # prints bar
print(l.foo) # prints bar

cc = copy.copy(c)
ll = copy.copy(l)
print(cc.foo) # prints {}
print(ll.foo) # prints bar

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[issue18352] collections.Counter with added attributes are not deepcopied properly.

2013-07-13 Thread Olivier Gagnon 

Olivier Gagnon added the comment:

Yes I do have code that break because of this behaviour. I'm doing evolutionary 
algorithm using a framework called DEAP. This framework creates a type called 
individual at the runtime by subclassing a container and adding it a fitness 
attribute. Those individual are copied as not to modify every indivual when we 
work on a single one. AFAIK the only container that can't be used right now is 
the counter because the fitness is not copied. I'm sure I can come up with a 
hack to have this behaviour, but it does clash with other standard container 
type and there is no mention anywhere that the Counter should be different than 
every other container type in the python standard library.

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