Hi everyone,
Trying to work with overlays I often need to write extreme amount of
boilerplate code just for transferring data between Java and Javascript.
(a) Take the following simple class as an example. I just want to run the
JS function stored in the private variable setFunc for different object
types. I understand that the Java objects (Double, Date, Integer etc.)
could not have to be appropriately converted, but in the cases of Strings
and the primitives it seems rather odd to have to repeat exactly the same
code over and over again.
(b) In addition, even the Java Objects are actually used by the application
as simple busses for transferring data from a JavaScript part to another
through the Java code (e.g. JavaScript nullable number to Double and then
back to JavaScript Number).
I suspect that the in both above cases (multiple identical methods and Java
Objects as busses) the compiler is not able to optimize the code, so
affecting the performance. One possible solution would be to use
JavaScriptObject as a bus, but, unfortunately, it seems that it cannot
store JS primitives.
I wonder if there is a better way for treating data transfers between JS
and Java or if the upcoming next generation JS interoperability solves the
problem. I’d appreciate any idea for better treating.
*public* *class* ViewPropWritable *extends* ViewProp {
*private* JavaScriptObject setFunc;
*private* JavaScriptObject data;
*public* ViewPropWritable(Binder view, ValueChangeListener uiElement,
String getExpr) {
*super*(view, uiElement, getExpr);
}
*public* ViewPropWritable(Binder view, ValueEditor uiElement,
String getExpr, String setExpr, String validExpr) {
*super*(view, uiElement, getExpr);
setFunc = getSetFunc(setExpr, validExpr);
((ValueEditor)uiElement).bindChangeEvent(*this*);
}
*public* *void* setScope(Scope scope) {
*this*.data = scope.getData();
}
*public* *boolean* setValue(Double value) {
*return* value == *null* ? setNull() : set(value.doubleValue());
}
*public* *boolean* setValue(Boolean value) {
*return* value == *null* ? setNull() : set(value.booleanValue());
}
*public* *boolean* setValue(Date value) {
*return* value == *null* ? setNull() : set(value.getTime());
}
*public* *native* *boolean* setValue(String value) /*-{
var f = [email protected]::setFunc;
return f(this.data, value);
}-*/;
* public* *native* *boolean* setValue(JavaScriptObject value) /*-{
var f = [email protected]::setFunc;
return f(this.data, value);
}-*/;
// Private methods
*private* *native* *boolean* set(*double* value) /*-{
var f = [email protected]::setFunc;
return f(this.data, value);
}-*/;
*private* *native* *boolean* set(*boolean* value) /*-{
var f = [email protected]::setFunc;
return f(this.data, value);
}-*/;
*private* *native* *boolean* setNull() /*-{
var f = [email protected]::setFunc;
return f(this.data, value);
}-*/;
*private* *native* JavaScriptObject getSetFunc(String setExpr, String
validExpr) /*-{
return function() {
var sf = new Function("$", "v", setExpr + "=v;");
if (validExpr) {
var vf = new Function("$", "v", validExpr);
return function(d, v) {
var b = v ? v(d, v) : true;
if (b) sf(d, v);
return b;
}
} else {
return function(d, v) {
return sf(d, v);
}
}
}();
}-*/;
}
BTW, the documentation of GWT 2.7 suggests that fully qualified class names
are not necessary anymore, but Eclipse complains if I set this.
@ViewPropWritable::setFunc for example.
Thanks,
Elias
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