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E4 Commands and Handlers [message #787666]

Tue, 31 January 2012 21:14

Josh Davis

Messages: 20
Registered: August 2011

Junior Member

Should this code work?

ECommandService eCommandService = context.get(ECommandService.class);
final Category lunch = eCommandService.getCategory("z.ex.view.keybindings.category");
        if (!lunch.isDefined()) {
            lunch.define("Lunch", "Actions take at lunch time.");
        }
final Command eatTaco = eCommandService.getCommand("z.ex.view.keybindings.eatTaco");
        if (!eatTaco.isDefined()) {
            eatTaco.define("Eat That Taco", "Go for the taco.", lunch);
        }

EHandlerService eHandlerService = context.get(EHandlerService.class);
final IHandler handler = new AbstractHandler() {
   public Object execute(final ExecutionEvent event) throwsExecutionException {
                System.out.println("Eat that Taco");
                return null;
            }
        };
        eHandlerService.activateHandler("z.ex.view.keybindings.eatTaco", handler);

I can't seem to get it to do what I am expecting.
I expect the command to be created (which it does) and then a handler added to the command (which it does not)
I copied this example from an example for adding commands and handlers in e3. I modified how the services are looked up

When activateHandler is called shouldn't eatTaco.getHandler() not be null? Unfortunately it is still null. I am having the same issue when I try to use the compatibility layer (IHandlerService and ICommandService is used in the e3 example)

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Re: E4 Commands and Handlers [message #787699 is a reply to message #787666]

Tue, 31 January 2012 22:04

Lars Vogel

Messages: 1098
Registered: July 2009

Senior Member

I don't think that will work. Mixing Eclipse 4 and Eclipse 3 is AFAIK not supported.

Not sure if you have seen this, but I have an updated version of my Eclipse 4 Tutorial online. I'm not covering exactly your case but I also show how to dynamically add model elements.

Mayby it helps.

[Updated on: Tue, 31 January 2012 22:25]

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Re: E4 Commands and Handlers [message #787708 is a reply to message #787699]

Tue, 31 January 2012 22:21

Josh Davis

Messages: 20
Registered: August 2011

Junior Member

Thanks for the reply Lars. I always check your tutorial and Tom's before I post. So I am familiar with it. If the solution to my issue is in your tutorial, I am not seeing it. I am not sure what you meant by "Mixing Eclipse 4 and Eclipse 4 is AFAIK not supported." I think you might have meant Eclipse 3?
I don't think my above code example has Eclipse 3 in it, unless I am overlooking something.
EHandlerService is a e4 class from what I can tell.

I mentioned e3 in my post because we also have some classes that are trying to add commands and activate handlers using the ICommandService and IHandlerService which I would expect to be handled by the compatibility layer. When I step through the code it looks like it is trying to activate the handler, however once the logic is done the command doesn't seem to be getting assigned the handler.

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Re: E4 Commands and Handlers [message #787716 is a reply to message #787708]

Tue, 31 January 2012 22:32

Lars Vogel

Messages: 1098
Registered: July 2009

Senior Member

Sorry I had a typo. I was referring to the following section: http://www.vogella.de/articles/Eclipse4RCP/article.html#importantmodelelement_examples

At the end of this chapter I show how you can add a model element dynamically. In my example a Part.

In your example your are using AbstractHandler, I believe you should try using the @Execute annotation.

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Re: E4 Commands and Handlers [message #787748 is a reply to message #787716]

Tue, 31 January 2012 23:40

Lars Vogel

Messages: 1098
Registered: July 2009

Senior Member

The following works for me:

Command command = commandService.getCommand("testing.throwingerror.aboutCommand");

// Returns true
System.out.println(command.isDefined());

// Activate Handler
handerService.activateHandler("testing.throwingerror.aboutCommand",new AboutHandler());

ParameterizedCommand cmd = commandService.createCommand("testing.throwingerror.aboutCommand", null);
command = commandService.getCommand("testing.throwingerror.aboutCommand");

// Return null and false, not sure why
System.out.println(command.getHandler());
System.out.println(command.isEnabled());

// Execution works file
System.out.println(handerService.canExecute(cmd));
handerService.executeHandler(cmd);

The only think I don't know is why isEnabled() and getHandler() return false and null.

Maybe Paul can clarify.

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Re: E4 Commands and Handlers [message #788242 is a reply to message #787748]

Wed, 01 February 2012 14:50

Lars Vogel

Messages: 1098
Registered: July 2009

Senior Member

I just asked Paul in IRC.

command.getHandler() and command.isEnabled() are for Eclipse 3.x based API and are not used in Eclipse 4. Hence they will always return null / false in Eclipse 4 applications.

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