> On 22 May 2017, at 15:09, Xiaodi Wu via swift-evolution
> <[email protected]> wrote:
>
> Let's be clear: it _is_ rounded, just toward zero. It is consistent with the
> behavior of integer division. I would guess that your students also
> repeatedly struggle with the result that `2 / 3 == 0`? If so, they have not
> been taught some important fundamentals of integer arithmetic. If not, then
> it should be natural that `Int(2 / 3 as Double == Int(2 / 3 as UInt)`.
Just to add my thoughts; but while I agree that it's important developers learn
the intricacies of Int vs. Float, I don't think this is quite the same issue as
divisions.
If you're asking for an Int then you should have some idea that you're asking
for a whole number only, and so that follows on to division as Ints simply
cannot handle fractions.
However, for conversion from Float there's an expectation that some rounding
must occur, the problem is that it's not as expected; while you or I would
expect it to be this way with familiarity of other languages, for someone new
to the language this isn't always going to be the case. While it's reasonable
to expect new developers to know what an Int is, I think it's unreasonable for
them also to remember what the default rounding strategy of an implicitly
rounding constructor is.
For this reason I tend to agree with the principle that the Int(_:Float)
constructor should probably be labelled more intuitively, personally I'd like
to see:
func init(truncating:Float) { … }
func init(rounding:Float, _ strategy: FloatingPointRoundingRule) { … }
Here the init(truncating:) constructor is just a convenience form of
init(rounding:) with a strategy of .towardZero, which I believe is consistent
with the current behaviour. It's also easily swapped in anywhere that
init(_:Float) etc. are currently used._______________________________________________
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