On 2010-04-01 16:52 PM, Ani wrote:
On Apr 1, 12:10 pm, Robert Kern<robert.k...@gmail.com> wrote:
On 2010-04-01 13:56 PM, Ani wrote:
Hi All:
I am just a beginner in python. Can anyone please tell me what is
wrong with this piece of code?
import copy
class BaseDummyObject(object):
def __init__(self):
pass
def __getattr__(self, item):
try:
return self.__dict__.__getitem__(item)
except KeyError:
print "Attribute Error: attr %s of class %s non-existent!"
%(item,
self.__class__.__name__)
You need to raise an AttributeError here. Otherwise, it implicitly returns None
for all attributes not in the __dict__ and thus confusing the copy.deepcopy()
code.
Thanks Robert. So I raised the exception and now everything looks
good. So what's happening here? When a certain attribute is not
available in the __dict__ and an exception is raised, who's catching
it?
copy.deepcopy(), in this case, or one of the functions it calls. You can use
traceback.print_stack() to see who is attempting to get the attribute. It is
checking for certain methods on the object which control how the object gets
seralized. copy.deepcopy() uses the same mechanism as pickle to serialize and
reconstruct the object in memory.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
--
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