Thanks for the clarification on the JSON vs JavaScript object. I
thought about using an overlay type earlier, but came away from the
documentation with the impression that overlays were intended to be
used for already existing objects "in the wild", but the technique you
demonstrate below seems to make sense and I will try it tomorrow.
On Jun 14, 4:51 pm, Thomas Broyer <t.bro...@gmail.com> wrote:
> On 14 juin, 20:28, markmccall <markwmcc...@gmail.com> wrote:
>
> > I am integrating a 3rd party JavaScript library into my GWT 2.0
> > application and I have succeeded in invoking the libary using basic
> > JSNI but I want to take the integration even further so that callers
> > of the library never have to code any JSNI, if possible. The 3rd
> > party library has a class Foo with a JSON structure as a constructore
> > parameter.
>
> JSON is a data format, what you're talking about is a JavaScript
> object, which you probably generally write directly as an object
> literal (the thing within braces, with comma-separated name:value
> pairs)
>
>
>
>
>
> > The structure contains simple properties as well as
> > predefined functions where users of this library can place custom own
> > behavior. Foo will call those functions to invoke the custom behavior
> > at time of is own choosing. In the example below I have shown 2
> > functions called 'onBeforeCompute' and 'onAfterCompute' which would be
> > invoked during Foo's loadData prcoess. The normal JSNI implementation
> > would look something like this:
>
> > public native JavaScriptObject setUp() /*-{
> > var config = {
> > prop1: 'val1',
> > prop2: 'val2',
> > onBeforeCompute: function(someparam) {
> > // do something custom here
> > },
> > onAfterCompute: function(someparam1, someparam2) {
> > // do something custom here
> > }};
>
> > var foo = $wnd.Foo(config);
> > foo.loadData(...)
>
> > }-*/
>
> > I would like to wrap all of this code up so that my applications that
> > use the 3rd party library never have to code any JSNI, if possible. I
> > am envisioning something like this:
>
> > public class MyWidget extends Composite
> > {
> > public MyWidget()
> > {
> > Config config = new Config();
> > config.setProp1("val1");
> > config.setProp2("val2");
> > config.setOnBeforeHandler(new MyOnBeforeComputeHandler());
> > config.setOnAfterHandler(new MyOnAfterComputeHandler());
> > Foo foo1 = new Foo(config);
> > SimplePanel panel = new SimplePanel(foo1);
> > initWidget(panel);
> > foo1.loadData(...);
> > }
>
> > }
>
> > public class MyOnBeforeComputeHandler implements
> > OnBeforeComputeHandler // interface definition excluded for brevity
> > {
> > public void onBeforeCompute(JavaScriptObject someparam)
> > {
> > // do something custom here
> > }
>
> > }
>
> > public class MyOnAfterComputeHandler implements
> > OnAfterComputeHandler // interface definition excluded for brevity
> > {
> > public void onAfterComputeHandler(JavaScriptObject someparam1,
> > JavaScriptObject someparam2)
> > {
> > // do something custom here
> > }
>
> > }
>
> > Setting the simple properties on the Config class is easy - I can
> > simply use the JSONObject, but I do not know how to deal with the
> > onBeforeCompute and onAfterCompute functions that are part of the
> > Config object
>
> > public class Config
> > {
> > private JSONObject jsonPeer = new JSONObject();
>
> Why not use a JavaScriptObject "overlay type"?
>
> > public void setProp1(String value){ jsonPeer.put ("prop1", value)};
> > public void setProp2(String value){ jsonPeer.put ("prop2", value)};
> > public asJson() {return jsonPeer.getJavaScriptObject());
> > public void setPreLoadHandler(PreLoadHandler handler) { ??? }
> > public void setPostLoadHandler(PostLoadHandler handler) { ??? }
>
> > }
>
> > Am I on the right track? Is there a better way?
>
> Re-written as an overlay type:
>
> public final class Config extends JavaScriptObject {
> public static Config newInstance() /*-{ }-*/;
>
> protected Config() { }
>
> public native void setProp1(String value) /*-{ this.prop1 = value; }-
> */;
> public native void setProp2(String value) /*-{ this.prop2 = value;}-
> */;
> public native void setPreLoadHandler(PreLoadHandler handler) /*-{
> var that = this;
> this.onBeforeCompute = $entry(function(someparam) {
> handl...@my.app.client.preloadhandler::onBeforeCompute(Lcom/
> google/gwt/core/client/JavaScriptObject;)(someparam);
> });
> }-*/;
> public native void setPostLoadHandler(PostLoadHandler handler) /*-{
> var that = this;
> this.onBeforeCompute = $entry(function(someparam) {
> handl...@my.app.client.postloadhandler::onAfterCompute(Lcom/
> google/gwt/core/client/JavaScriptObject;Lcom/google/gwt/core/client/
> JavaScriptObject;)(someparam1, someparam2);
> });
> }-*/;
>
>
>
> }
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