generate exception when encoding duplicate keys

[arman0]

>>> pyamf.decode(pyamf.encode({0:0, '0':1})).next()
{u'0': 1}

My guess is that the user almost always has a bug when encoding a python dict which will result in duplicate AS object keys. Therefore, it would be help for pyamf to raise an exception in such cases.

-arman

[nick]

Branching to source:pyamf/branches/duplicate-keys-458

[nick]

Encoding the example dict now raises an AttributeError:

>>> import pyamf
pyamf.encode({0:0, '0':1})
>>> pyamf.encode({0:0, '0':1})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "pyamf/__init__.py", line 1069, in encode
    encoder.writeElement(el)
  File "pyamf/amf0.py", line 541, in writeElement
    func(data)
  File "pyamf/amf0.py", line 758, in writeObject
    obj_attrs = self._getObjectAttrs(o, alias)
  File "pyamf/amf0.py", line 722, in _getObjectAttrs
    obj_attrs = util.get_attrs(o)
  File "pyamf/util/__init__.py", line 732, in get_attrs
    'different key types?' % (sk,))
AttributeError: A duplicate attribute (0) was already found in this collection, are you mixing different key types?

[thijs]

I added a docstring for the AttributeError in r2204.

The test from the ticket description worked and ParseDump succeeded, so ready to merge.

[nick]

Merged in r2206.