Wednesday, August 23, 2017

Re: ClassCastException in generics

On Wednesday, August 23, 2017 at 2:15:32 PM UTC+2, Kirill Prazdnikov wrote:
    instanceOfArrayBuffer for file = false
    instanceOfArrayBuffer for good copy = true
 Uncaught Error: java.lang.ClassCastException 

I think that it is a problem for generics. 
GWT will fail its checkcast for any instance of system type (like array buffer or whatever) for any class created other in any context other then $wnd.

JS "new ArrayBuffer(10)" and "new $wnd.ArrayBuffer(10)" has different type from GWT point of view.

From JS point of view:

Then my next question: 

if GWT generates checkckast as "yze_g$(fileBuffer_0_g$, $wnd.ArrayBuffer)",  where "$wnd.ArrayBuffer" is a type
how can I ask GWT to generate checkckast  to ArrayBuffer, not to $wnd.ArrayBuffer ?

In case you really need to reference a type in GWT's hidden iframe, then you can use namespace="<window>" instead of namespace=GLOBAL; but this is undocumented behavior that could possibly change or break at any time.
Better fix you JSNI to use $wnd, or use JsInterop all the way down, with namespace=GLOBAL.

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