Class destructor -- strange behaviour

[Spes]

Hi,

I have this simple code:
| #!/usr/bin/python
| import codecs
| import re
| from copy import deepcopy
|
| class MyClass(object):
| def __del__(self):
| deepcopy(1)
|
| x=MyClass()

but I get an error:
| Exception exceptions.TypeError: "'NoneType' object is not callable"
in <bound method MyClass.__del__ of <__main__.MyClass object at
0x6fcf0>ignored

The problem disappears if I do anything of this:
1. change
- from copy import deepcopy
+ import copy
and call directly copy.deepcopy(1)

or
2. don't store object to variable `x'

or
3. don't import module `re'

The first solution is OK, but I would like to know why it behaves so
strange. We have tested on:

- Mac OS X Tiger for PPC
Python 2.3.5 (#1, Mar 20 2005, 20:38:20)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1809)] on darwin

- Linux 64bit and 32bit
Python 2.4.4 (#1, Oct 30 2007, 14:31:50)
[GCC 4.1.2 (Gentoo 4.1.2 p1.0.2)] on linux2
Python 2.5 (r25:51908, Jan 12 2007, 13:57:15)
[GCC 4.0.2 20051125 (Red Hat 4.0.2-8)] on linux2

Thanks for the explanation,
Vlasta

[MonkeeSage]

On Dec 6, 3:51 pm, Spes <[e-mail]:

Hi,

I have this simple code:
| #!/usr/bin/python
| import codecs
| import re
| from copy import deepcopy
|
| class MyClass(object):
| def __del__(self):
| deepcopy(1)
|
| x=MyClass()

but I get an error:
| Exception exceptions.TypeError: "'NoneType' object is not callable"
in <bound method MyClass.__del__ of <__main__.MyClass object at
0x6fcf0>ignored

The problem disappears if I do anything of this:
1. change
- from copy import deepcopy
+ import copy
and call directly copy.deepcopy(1)

or
2. don't store object to variable `x'

or
3. don't import module `re'

The first solution is OK, but I would like to know why it behaves so
strange. We have tested on:

- Mac OS X Tiger for PPC
Python 2.3.5 (#1, Mar 20 2005, 20:38:20)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1809)] on darwin

- Linux 64bit and 32bit
Python 2.4.4 (#1, Oct 30 2007, 14:31:50)
[GCC 4.1.2 (Gentoo 4.1.2 p1.0.2)] on linux2
Python 2.5 (r25:51908, Jan 12 2007, 13:57:15)
[GCC 4.0.2 20051125 (Red Hat 4.0.2-8)] on linux2

Thanks for the explanation,
Vlasta

I can't explain why, but it also works if you call del x manually
before the script exits.

Regards,
Jordan

[Jason]

On Dec 6, 2:51 pm, Spes <[e-mail]:

Hi,

I have this simple code:
| #!/usr/bin/python
| import codecs
| import re
| from copy import deepcopy
|
| class MyClass(object):
| def __del__(self):
| deepcopy(1)
|
| x=MyClass()

but I get an error:
| Exception exceptions.TypeError: "'NoneType' object is not callable"
in <bound method MyClass.__del__ of <__main__.MyClass object at
0x6fcf0>ignored

The problem disappears if I do anything of this:
1. change
- from copy import deepcopy
+ import copy
and call directly copy.deepcopy(1)

or
2. don't store object to variable `x'

or
3. don't import module `re'

The first solution is OK, but I would like to know why it behaves so
strange. We have tested on:

- Mac OS X Tiger for PPC
Python 2.3.5 (#1, Mar 20 2005, 20:38:20)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1809)] on darwin

- Linux 64bit and 32bit
Python 2.4.4 (#1, Oct 30 2007, 14:31:50)
[GCC 4.1.2 (Gentoo 4.1.2 p1.0.2)] on linux2
Python 2.5 (r25:51908, Jan 12 2007, 13:57:15)
[GCC 4.0.2 20051125 (Red Hat 4.0.2-8)] on linux2

Thanks for the explanation,
Vlasta

Gabriel nailed the problem down. Another solution is to explicitly
import module names in your destructor, ie:

def __del__(self):
from copy import deepcopy
deepcopy(1)

This guarantees that your destructor has "deepcopy" binding that you
want, even if the name has already been reassigned to None in your
current module by the interpreter as it is shutting down.

--Jason