[records] equality on float / double components

[Paul Sandoz]

> On 6 Dec 2017, at 10:22, Kevin Bourrillion <kevinb at google.com> wrote:
> 
> I'd strongly expect this to behave exactly as Float.equals() does. The +0.0/-0.0 problem exists but is nothing new.
> 

I concur. Float/Double.equals/compare is also used for float/double[] array equals and compare.

Paul.

> 
> On Wed, Dec 6, 2017 at 1:07 PM, Brian Goetz <brian.goetz at oracle.com <mailto:brian.goetz at oracle.com>> wrote:
> It's time to play everyone's favorite game show, "What about NaN".
> 
> If we have a record:
> 
>     record Foo(float f);
> 
> We would like Object.equals() to be reflexive, symmetric, and transitive.  But if we define equals() in the obvious way (delegating to float==), then `new Foo(Float.NaN`) would not be equal to itself.
> 
> If we delegate instead to `Float.compare(this.f, that.f)`, the NaN problem goes away (though comparison becomes modestly more expensive), but now +0 and -0 are distinguished (== treats them the same.)
> 
> 
> 
> 
> --
> Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com <mailto:kevinb at google.com>
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