[Python-Dev] cpython: fix compiler warning by implementing this more cleverly (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Wed Nov 23 08:07:15 CET 2011

On Wed, Nov 23, 2011 at 4:49 PM, Terry Reedy <tjreedy at udel.edu> wrote:

I personally strongly prefer the one-line formula to the hardcoded magic numbers calculated from the formula. I find it much more readable. To me, the only justification for the switch would be if there is a serious worry about the kind being changed to something other than 1, 2, or 4. But the fact that this is checked with an assert that can be optimized away negates that. The one-liner could be followed by  assert(kind==1 || kind==2 || kind==4) which would also serve to remind the reader of the possibilities. You could even follow the formula with /* 4, 6, or 10 */ I think you reverted too soon.

+1 to what Terry said here, although I would add a genuinely explanatory comment that gives the calculation meaning:

/* For each character, allow for "\U" prefix and 2 hex digits per byte */
expandsize = 2 + 2 * kind;

Cheers, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

More information about the Python-Dev mailing list