prototype proplem

[suziwen]

function clock(){

}

clock.prototype = new qt.QWidget();
clock.prototype.printvalue = function(){
console.log('xxx');
}

var clocka = new clock();

and when run
problem :
.node-gyp/0.8.16/src/node_object_wrap.h:61: static T* node::ObjectWrap::Unwrap(v8::Handlev8::Object) [with T = QWidgetWrap]: Assertion `handle->InternalFieldCount() > 0' failed.
已放弃