You are right of course, there needs to be consistency between typeof
operator and treatment as JS numbers.
This is in fact an unpleasant problem to solve. I've struggled trying to
fix this without breaking any existing code, but I've come to the
conclusion that it is not possible. Since we can't treat all Java
longs/Longs as JS numbers, we'd have to differentiate depending on
whether the value can be represented as double without losing precision.
In a way we already do this with optimistic types, but I consider it
more a bug than a feature. It's weird (and error prone) if the return
value for a Java method returning long is reported as number or object
depending on the actual value.
So I think the right thing to do is draw a clear line between which Java
primitive/wrapper types represent JS numbers and which don't. I've
uploaded a new webrev that implements this:
http://cr.openjdk.java.net/~hannesw/8143896/webrev.01/
Note that the only types to be treated as JS numbers are the direct
wrapper classes for Java primitives that can be fully represented as
doubles. This means also things like AtomicInteger and DoubleAdder will
be reported and treated as objects. I think that's the correct thing to
do as they are not primitive numbers in the first place. They are still
converted to numbers when used in such a context in JS. So I think the
only place where this change is a actually painful/surprising is longs.
Unfortunately the check for number type in JSType.isNumber gets a bit
long as we have to individually check for all primitive wrapper classes.
I've done extensive benchmarking and I don't think it has an impact on
performance. In any way, I wouldn't know how to handle this differently.
Let me know what you think.
Hannes
Am 2016-01-04 um 05:00 schrieb Sundararajan Athijegannathan:
I think I already commented on this webrev -- that we need to cover
tests for BigInteger, BigDecimal.
Also, I'm not sure linking Double and Int by nashorn primitive
linkers is the right solution. AtomicInteger, DoubleAdder etc. are all
Number subtypes. We return "number" when typeof is used on any Number
subtype.
Now, that means JS code will see these as 'number' type objects -- yet
Number.prototype methods won't work on those!! I know this is hard
problem -- we also have another (somewhat related) BigDecimal,
BigInteger toString / String conversion issue. We need to discuss this.
-Sundar
On 1/2/2016 8:29 PM, Attila Szegedi wrote:
+1
On Dec 18, 2015, at 3:54 PM, Hannes Wallnoefer
<hannes.wallnoe...@oracle.com> wrote:
Please review JDK-8143896: java.lang.Long is implicitly converted to
double
http://cr.openjdk.java.net/~hannesw/8143896/webrev/
Thanks,
Hannes
