[PROTON-1835] [python] Use of Python dict for AMQP maps does not allow derived or related keys of the same value

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: python-binding
• Assignee: Unassigned
• Reporter: Kim van der Riet
• Created: 25/Apr/18 15:00
• Updated: 02/May/18 22:18

Description

The AMQP map (expressed as a list) [binary(123), "hello", decimal128(123), "world"] cannot be implemented in Python using the dict type. This happens because proton.decimal is derived from bytes, and the dictionary treats the keys as the same value and causes the first value to be overwritten by the second:

>>> import proton
>>> {b'123': 'hello', proton.decimal128(b'123'): 'world'}
{'123': 'world'}

Using the [] operator to add the values one at a time to an empty dict results in the same outcome. Even using related classes (ie both derived from a common parent) don't work:

>>> import proton
>>> class mybin(bytes):
...     def __repr__(self):
...         return 'mybin(%s)' % bytes.__repr__(self)
... 
>>> {mybin(b'123'): 'hello', proton.decimal128(b'123'): 'world'}
{mybin('123'): 'world'}