pointless musings on performance

Rob Williscroft rtw at freenet.co.uk
Tue Nov 24 13:31:37 CET 2009


mk wrote in news:mailman.915.1259064240.2873.python-list at python.org in 
comp.lang.python:

> 
> def pythonic():
 
> def unpythonic():
 
 
> Decidedly counterintuitive: are there special optimizations for "if 
> nonevar:" type of statements in cpython implementation?
> 

from dis import dis

dis( unpythonic )

18          31 LOAD_FAST                0 (nonevar)
             34 LOAD_CONST               0 (None)
             37 COMPARE_OP               9 (is not)
             40 JUMP_IF_FALSE            4 (to 47)

dis( pythonic )

11          31 LOAD_FAST                0 (nonevar)
             34 JUMP_IF_FALSE            4 (to 41)
 
Rob.
 




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