On Tue, Sep 27, 2011 at 1:05 PM, Alexander Belopolsky <alexander.belopol...@gmail.com> wrote: > On Tue, Sep 27, 2011 at 2:53 PM, Guido van Rossum <gu...@python.org> wrote: >> On Tue, Sep 27, 2011 at 11:48 AM, Alexander Belopolsky >> <alexander.belopol...@gmail.com> wrote: >>> On Tue, Sep 27, 2011 at 2:36 PM, Guido van Rossum <gu...@python.org> wrote: >>> .. >>>> But that's exactly what we don't *want* you to do! Because (unless you >>>> are a numerical wizard) you probably aren't doing the error analysis >>>> needed to avoid the "unexpected extra point" problem due to floating >>>> point inaccuracies. For your own good, we want you to state the count >>>> and let us deliver the number of points you want. > > I don't disagree that the ability to provide count= option is useful. > I am just saying that there are also cases where float step is known > exactly and count (or stop) can be deduced from stop (or count) > without any floating point issues. Iteration over integers that > happen to be represented by floats is one use case, but using integer > range may be a better option in this case. In US it is still popular > to measure things in power of two fractions. Simulating a carpenter's > yard does not suffer from rounding when done in floats. Counting by > .5 and .25 has its uses too. Maybe frange() should just signal the FP > inexact exception if we expect users to need hand holding to such a > degree.
But why offer an API that is an attractive nuisance? I don't think that it is a burden to the user to have to specify "from 0 to 2 inches in 8 steps" instead of "from 0 to 2 inches in 1/4 inch steps". (And what if they tried to say "from 0 to 3 1/4 inches in 1/2 inch steps" ?) -- --Guido van Rossum (python.org/~guido) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
