FXMLLoader templates

[Martin Sladecek]

After discussion with Richard, we decided to remove the template flag 
from FXMLLoader for 8.0.
This API is not mature yet, due to the reasons described below and 
should be completely re-designed for some next release.

This means that loading the same fxml multiple times will still require 
multiple FXMLLoader instances.

Any comments?

Thanks,
-Martin

On 09/20/2013 02:22 PM, Martin Sladecek wrote:
> Hi,
> I would like to discuss a 8.0 feature of FXMLLoader - the template flag.
> I was introduced with this issue: 
> https://javafx-jira.kenai.com/browse/RT-23413, but unfortunately, it 
> never worked: https://javafx-jira.kenai.com/browse/RT-28121. I was 
> trying to fix the issue, but the whole concept of a flag for loading 
> templates seems hardly usable and incorrect to me and should be 
> replaced with something more appropriate.
>
> The reason is the handling of root, controller and the namespace 
> before and after the load. Both are treated in 2 different ways. 
> Before the load, they are used to adjust the following load - by 
> setting the root (for <fx:root> tag), setting the namespace and a 
> controller.
> However, after the load, these properties (though not FX-properties) 
> can be used to query what was just loaded. The root of the FXML, the 
> namespace with all "id"s and the controller.
>
> Now that's not very useful when you want to use template loading. My 
> solution for RT-28121 (when keeping the old API) is to save the 
> namespace after setTemplate(true) was called, using this namespace on 
> each load(), clearing it at the begging of load() +  disallow 
> setController() for this mode.
>
> But that doesn't cover all of the relevant use-cases I can think of. 
> Actually, without changing the API, I doubt we can support all such 
> use-cases.
>
> Here's the set I'm working with:
> 1) setup some "template namespace", n times do { adjust namespace 
> (based on template namespace) , load) }
>
> 2) n times do {load, query id from namespace}
>
> 3) n times do {setController(new Controller) load }
>
> 4) n times do {load, query newly created controller}
>
> 5,6) same as 3,4 but with root
>
> So while in 1,3 we would need to clear namespace/controller after each 
> load, in 2,4 we need to clear it before each load. In case 3), 
> forgetting to set a new controller would otherwise result in 2 
> instances with the same controller.
>
> One solution might be to split this to 2 independent calls. 
> setController/getLoadedController, ObservableMap getNamespace() and 
> Map getLoadedNamespace (unmodifiable).
>
> Another might be a completely new class FXMLTemplate.
> It might yield new pre-set FXMLLoaders that can be adjusted and 
> loaded, but it means generating a temporary object for each call.
> Also, FXMLLoader would need to be updated, so that it's only possible 
> to call load() once.
>
> Other ideas / use-cases?
>
> Thanks,
> -Martin