while 1 vs while True

Dan Bishop danb_83 at yahoo.com
Mon Dec 13 02:59:25 CET 2004


Timothy Fitz wrote:
> [ http://www.python.org/moin/PythonSpeed ]
> "Starting with Py2.3, the interpreter optimizes 'while 1' to just a
> single jump. In contrast "while True" takes several more steps. While
> the latter is preferred for clarity, time-critical code should use
the
> first form."
>
> Out of pure curiousity,
> Why wasn't 'While True' optimized also?

Probably has something to do with "True" and "False" not being
constants.

>>> True = 0
>>> while True:
...    print 'Not an infinite loop.  In fact, it never executes at all.'




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