398396 - Arithmetic mixing boxed (java) numbers and js numbers

Status: RESOLVED DUPLICATE of bug 371443

(Rhino Graveyard :: Core, defect)

Description

[Christophe Grand]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; fr; rv:1.8.1.7) Gecko/20070914 Firefox/2.0.0.7
Build Identifier: 

new java.lang.Double("3") + 1 returns "31".

Reproducible: Always

Steps to Reproduce:
At a rhino shell enter:
new java.lang.Double("3") + 1
Actual Results:  
31 (String)

Expected Results:  
4 (Number)

Comment 1

[Christophe Grand]

Attachment: NativeJavaObject.defaultValue(Class hint) defaults to Number when javaObject is an instanceof Number (and hint is null).

Comment 2

[Christophe Grand]

Oops: WrapFactory.setJavaPrimitiveWrap(false) solves my core problem but not "new java.lang.Double("3") + 1 returns "3.01"".

Comment 3

[Attila Szegedi]

Okay, so the + operator calls ToPrimitive() on both its left and right side (ECMA spec 11.6.1). Now, if you're *explicitly* creating a java.lang.Double, you're acknowledging that you're creating an object, and unhinted toPrimitive for objects will always call defaultValue on them (9.1), and defaultValue will ultimately invoke toString (Number hint step 5 in 8.6.2.6).

Ultimately, setJavaPrimitiveWrap() is used to decide whether to wrap or not return values from methods. If you're explicitly creating objects in your scripts, they're never considered primitive. 

So, everything operates as expected :-)

Comment 4

[Attila Szegedi]

Bug 371443 gives you further pointers if you want to implement your desired functionality

Comment 5

[Christophe Grand]

Thank you Attila for these explanations. 

As I said: my problem (doubles becoming Doubles because of being boxed to fit in a Map) was solved by using setJavaPrimitiveWrap.