[Python-Dev] Strategy for converting the decimal module to C

[Georg Brandl]

Raymond Hettinger wrote:
> 
>>> I think it was tripping-up the folks working on the C implementation. 
>>> Georg can speak to it more directly.  IIRC, the issue was that the
>>> context object exposed a dictionary which a user could update directly
>>> and there was no notification back to the surrounding object so it could
>>> update an underlying bitfield representation.
>>>     
>>
>> Yes, that's exactly what the problem was. Working with bitfields internally
>> is fine as long as Python code doesn't want to change the dicts exposed
>> as a wrapper.
>>   
> 
> If you want to stick with dictionary-like access to traps and flags,
> then use a dict subclass that overrides each of the mutating methods.

That may be easiest to do in Python code. I'll leave it to Mateusz to decide.

> Even then, we need to drop the concept of having the flags as counters
> rather than booleans.

Yes. Given that even Tim couldn't imagine a use case for counting the
exceptions, I think it's sensible.

Georg