Draft proposal: allow the use of relational operators on Comparable classes

[Neal Gafter]

Actually, I was referring to issues like the treatment of NaN,
negative zero, and the like.  Given

Float x1 = NaN;
Float x2 = NaN;

currently x1 <= x2 is false.  Under this proposal it would be true.
That's a breaking change.

-Neal

On Tue, Mar 10, 2009 at 5:03 PM, Reinier Zwitserloot
<reinier at zwitserloot.com> wrote:
> Reply inline
>
>  --Reinier Zwitserloot
>
>
>
> On Mar 10, 2009, at 17:21, Neal Gafter wrote:
>
>> This proposal is incompatible with the existing behavior of the
>> comparison operators on the boxed value classes, particularly for
>> Float and Double.
>>
>
> I'll help Neal out and be a bit more verbose:
>
> Existing behaviour unboxes first, which also means that you get type
> promotion to make parts fit. You can do this:
>
> Float x = 10.0;
> Double y = 12.0;
>
> if ( x < y ) /* stuff */;
>
> but you can not call x.compareTo(y), or y.compareTo(x). (AFAIK - it
> would be nice if someone tests this theory. Don't have a javac
> available at the moment).
>
> Easily fixed in the proposal by stating: If the operation would
> succeed under old unboxing rules, use those.
>
> After all, there are ambiguous rules regarding == as well (if I == two
> autoboxed values, is it reference comparison, or an equals check)? A
> choice was made there too.
>
>> On Tue, Mar 10, 2009 at 9:09 AM, Vilya Harvey
>> <vilya.harvey at gmail.com> wrote:
>>> I've attached a draft of a proposal to allow classes which
>>> implement the
>>> Comparable interface to be used as operands for the relational
>>> operators. So
>>> for example if you had two Strings, a and b, you would be able to
>>> write
>>>
>>> if (a < b) {
>>>    ...
>>> }
>>>
>>> instead of
>>>
>>> if (a.compareTo(b) < 0) {
>>>    ...
>>> }
>>>
>>> and you could do the same with your own classes as well.
>>>
>>> Thanks in advance for any feedback,
>>>
>>> Vil.
>>>
>>>
>>>
>>>
>>
>
>
>