Hello,
I was learning Cython from this tutorial when I noticed a glitch:
Near the end, after boundscheck False, some variables are changed to
unsigned int. But this has unexpected consequences: variables t_from and such
are not determined correctly, as one of the arguments is negative, but gets
cast to unsigned for comaprison. (Yes, this is a weird feature of C.)
Actually, the use of unsigned does not seem to have any impact on performance,
so I suggest to scratch that part of tutorial. Just explain that with
boundscheck
off, negaitive indices no longer work.
(But there might perhaps be one small improvent in cython itself: with
boundscheck
off, the index might be cast to unsigned before it is used: this way we
probably
crash on negative values, instead of silently accessing the negative offset of
the array data.)
Thank you for nice piece of software,
Stepan Kasal
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