is None or == None ?

Alf P. Steinbach alfps at start.no
Fri Nov 6 19:45:02 CET 2009


* Hrvoje Niksic:
> "Alf P. Steinbach" <alfps at start.no> writes:
> 
>> But wow. That's pretty hare-brained: dynamic allocation for every
>> stored value outside the cache range, needless extra indirection for
>> every operation.
>>
>> Even Microsoft COM managed to get this right.
>>
>> On the positive side, except that it would probably break every C
>> module (I don't know), in consultant speak that's definitely a
>> potential for improvement. :-p
> 
> Tagged integers have been tried, shown not really worth it, and
> ultimately rejected by the BDFL:
> 
> http://mail.python.org/pipermail/python-dev/2004-July/thread.html#46139

Yah, as I suspected. I looked at the first few postings in that thread and it 
seems an inefficient baroque implementation was created and tested, not 
realizing more than 50% speedup in a test not particularly much exercising its 
savings, and against that counts as mentioned in the thread and as I mentioned 
in quoted material above, breaking lots of existing C code.

Speedup would likely be more realistic with normal implementation (not fiddling 
with bit-fields and stuff) not to mention when removing other inefficiencies 
that likely dwarf and hide the low-level performance increase, but still I agree 
wholeheartedly with those who argue compatibility, not breaking code.

As long as it Works, don't fix it... ;-)


Cheers, (still amazed, though)

- Alf



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