On Thu, 31 Dec 2015 00:11:24 +1100, Chris Angelico wrote:
> On Wed, Dec 30, 2015 at 11:57 PM, Charles T. Smith
> <cts.private.ya...@gmail.com> wrote:
>> Hello,
>>
>> I thought __getitem__() was invoked when an object is postfixed with an
>> expression in brackets:
>>
>> - abc[n]
>>
>> and __getattr__() was invoked when an object is postfixed with an dot:
>>
>> - abc.member
>
> That would be normal (with the caveat that __getattr__ is called only if
> the attribute isn't found; __getattribute__ is called unconditionally).
>
>> but my __getitem__ is being invoked at this time, where there's no
>> subscript (going into a spiral recursion death):
>>
>> self.mcc = self.attrs.mcc
>>
>> Can anybody explain to me why __getitem__() would be invoked here?
>
> Can you post your entire class, or at least __getattr__? Also check
> superclasses, if there are any.
>
> ChrisA
(PDB)isinstance (self.attrs, attrdict)
True
As is so often the case, in composing my answer to your question, I discovered
a number of problems in my class (e.g. I was calling __getitem__() myself!), but
I'm puzzled now how to proceed. I thought the way you avoid triggering
__getattr__()
from within that was to use self.__dict__[name] but that doesn't work:
(PDB)p self.attrs.keys()
['mcc', 'abc']
(PDB)p self.attrs.__dict__['abc']
*** KeyError: KeyError('abc',)
class attrdict(dict):
def __init__ (self, name = None):
if name:
self.update (name)
print "attrdict: instantiated: ", name
# AutoVivification
def __getattr__ (self, name):
print "attrdict:av:__getattr__: entered for ", name #, " in ", self
#if not name in self.__dict__.keys():
if not name in self.keys():
print "attrdict:av:__getattr__: autovivifying ", name
#self.__dict__.__setitem__ (name, self.__class__())
#self.__setitem__ (name, self.__class__())
self.__setattr__ (name, self.__class__())
#return self.__getitem__(name)
#return self.__dict__.__getitem__(name)
return self.__getattribute__ (name)
def __getitem__ (self, key):
print "attrdict:av:__getitem__: entered for ", key #, " in ", self
return self.__getitem__(key)
def __getattr__deprecated (self, name):
return self[name]
def __setattr__(self, name, value):
self[name] = value
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