Hello all,
This morning I tried to create my own read-only dictionary, and failed
miserably.
I don't understand why, can somebody enlighten me?
Below is a brute-force experiment that cannot deal with "x in obj", plz read
the explanation below the code:
--------------------------------
class myowndict(object):
def __init__(self, mydict):
self.mydict = mydict
# Below is produced with
# print '\n'.join([' self.%s = self.mydict.%s' % (v,v)
# for v in dir(dict)])
# commented-out functions done by hand
#
#self.__class__ = self.mydict.__class__
self.__cmp__ = self.mydict.__cmp__
self.__contains__ = self.mydict.__contains__
self.__delattr__ = self.mydict.__delattr__
self.__delitem__ = self.mydict.__delitem__
#self.__doc__ = self.mydict.__doc__
self.__eq__ = self.mydict.__eq__
self.__ge__ = self.mydict.__ge__
self.__getattribute__ = self.mydict.__getattribute__
self.__getitem__ = self.mydict.__getitem__
self.__gt__ = self.mydict.__gt__
self.__hash__ = self.mydict.__hash__
#self.__init__ = self.mydict.__init__
self.__iter__ = self.mydict.__iter__
self.__le__ = self.mydict.__le__
self.__len__ = self.mydict.__len__
self.__lt__ = self.mydict.__lt__
self.__ne__ = self.mydict.__ne__
#self.__new__ = self.mydict.__new__
self.__reduce__ = self.mydict.__reduce__
self.__reduce_ex__ = self.mydict.__reduce_ex__
self.__repr__ = self.mydict.__repr__
self.__setattr__ = self.mydict.__setattr__
self.__setitem__ = self.mydict.__setitem__
self.__str__ = self.mydict.__str__
self.clear = self.mydict.clear
self.copy = self.mydict.copy
self.fromkeys = self.mydict.fromkeys
self.get = self.mydict.get
self.has_key = self.mydict.has_key
self.items = self.mydict.items
self.iteritems = self.mydict.iteritems
self.iterkeys = self.mydict.iterkeys
self.itervalues = self.mydict.itervalues
self.keys = self.mydict.keys
self.pop = self.mydict.pop
self.popitem = self.mydict.popitem
self.setdefault = self.mydict.setdefault
self.update = self.mydict.update
self.values = self.mydict.values
# end of __init__
if __name__ == '__main__':
fd = myowndict({1:10})
print 1 in fd # FAILS! (with "TypeError: iterable argument required")
--------------------------------
I wanted to make my own dictionary. However, a simple element test failed
(after implementing various __*__ functions), and I cannot figure out why.
The above code is a brute force attempt, where I forward all methods (except
__class__, __doc__, __init__, and __new__) to my local 'mydict' object.
IT STILL FAILS.
So if copying all methods of a native dictionary is not enough, what should I
do to make my class work as a dictionary WITHOUT deriving from dict (which will
obviously work).
Sincerely,
Albert
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