[Python-Dev] Octal literals (original) (raw)

Josiah Carlson jcarlson at uci.edu
Sun Feb 5 18:38:35 CET 2006

bokr at oz.net (Bengt Richter) wrote:

Martin v. Lowis <martin at v.loewis.de> wrote: >Bengt Richter wrote: >>>The typical way of processing incoming ints in C is through >>>PyArgParseTuple, which already has the code to coerce long->int >>>(which in turn may raise an exception for a range violation). >>> >>>So for typical C code, 0x80000004 is a perfect bit mask in Python 2.4. >> >> Ok, I'll take your word that 'k' coercion takes no significant time for longs vs ints. > >I didn't say that 'k' takes no significant time for longs vs ints. In >fact, I did not make any performance claims. I don't know what the >relative performance is.

Sorry, I apologize for putting words in your mouth.

In regards to the aesthetics and/or inconsistancies of:

-0x80000000 -2147483648L -2147483648 -2147483648 -(2147483648) -2147483648L

  1. If your Python code distinguishes between ints and longs, it has a bug.

  2. If your C extension to Python isn't using the 'k' format specifier as Martin is telling you to, then your C extension has a bug.

  3. If you are concerned about potential performance degredation due to a use of 'k' rather than 'i' or 'I', then you've forgotten the fact that Python function calling is orders of magnitude slower than the minimal bit twiddling that PyInt_AsUnsignedLongMask() or PyLong_AsUnsignedLongMask() has to do.

Please, just use 'k' and let the list get past this.

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