Review: JDK 8 CR for Support Integer overflow

[Eamonn McManus]

I'm with Roger on this.

> Sorry, but I can't agree with this. Developers get negation of numbers
> wrong all the time by ignoring the special case. Its a big source of
> hidden bugs. Increment/decrement are replaceable by add/subtract (with
> less readability), but negate is not.

First of all, negate(x) certainly is replaceable by subtractExact(0,
x). Secondly, the problem is more that people don't realize that -x
might not be exact. If you know there's a problem then it isn't any
easier for you to know that a solution is to be found in Math than to
know that the problem is with MIN_VALUE.

Éamonn



On 6 February 2012 14:35, Stephen Colebourne <scolebourne at joda.org> wrote:
> On 6 February 2012 21:16, Roger Riggs <Roger.Riggs at oracle.com> wrote:
>>  * Removed the negateExact methods since they don't pull their weight
>>   in the API,
>>   simple tests for MIN_VALUE and MAX_VALUE can be done by the
>>   developer more efficiently.
>
> Sorry, but I can't agree with this. Developers get negation of numbers
> wrong all the time by ignoring the special case. Its a big source of
> hidden bugs. Increment/decrement are replaceable by add/subtract (with
> less readability), but negate is not.
>
> The whole purpose of methods like this is not to say "oh they're easy
> for the caller to write", but to write it once accurately,
> well-tested, and with clear intent for code readers. Look at the
> methods on Objects to see that complexity of the implementation is not
> the deciding factor.
>
> Many, many developers will thank you for having negate, increment and decrement.
>
> Stephen