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Active Perspective Core Expression [message #1219011]

Fri, 29 November 2013 10:34

Eclipse User

Hi,

I've already got around this in a different way but is there a core expression to get the Active Perspective Id in pure e4?

I have found below expression online but 'activeWorkbenchWindow.activePerspective' seems not to contain the Active Perspective Id. Is this known to be broken in e4?

<extension point="org.eclipse.core.expressions.definitions">
      <definition id="onValidationPerspective">
         <with variable="activeWorkbenchWindow.activePerspective">
               <equals value="com.sample.perspective1"/>
          </with>
      </definition>
</extension>

I also did try querying the variable with context.get("activeWorkbenchWindow.activePerspective") but it always returns 'null'.

Is there any other core expression that replaces this in e4?

Regards,

Ozgur.

Re: Active Perspective Core Expression [message #1219974 is a reply to message #1219011]

Sat, 07 December 2013 15:23

Eclipse User

On 11/29/13, 8:34 AM, Ozgur Cagdas wrote:
> Hi,
>
> I've already got around this in a different way but is there a core
> expression to get the Active Perspective Id in pure e4?
>
> I have found below expression online but
> 'activeWorkbenchWindow.activePerspective' seems not to contain the
> Active Perspective Id. Is this known to be broken in e4?
>
> <extension point="org.eclipse.core.expressions.definitions">
> <definition id="onValidationPerspective">
> <with variable="activeWorkbenchWindow.activePerspective">
> <equals value="com.sample.perspective1"/>
> </with>
> </definition>
> </extension>
>
>
> I also did try querying the variable with
> context.get("activeWorkbenchWindow.activePerspective") but it always
> returns 'null'.
>
> Is there any other core expression that replaces this in e4?
>
> Regards,
>
> Ozgur.
>
Did this ever get answered? I have similar question about how to write
a core expression to define a perspective BEFORE I have actually written
any code - I am working with the application model and would like to
make menu items visible based on perspectives.

Re: Active Perspective Core Expression [message #1221040 is a reply to message #1219974]

Mon, 16 December 2013 13:57

Eclipse User

Pure e4 apps don't have a 'WorkbenchWindow' from which the 'activePerspective' could be determined. In e4 you work against the model;

- Find the MPerspectiveStack using the EModelService's 'findElements' API
- It's 'selectedElement' is the currently active perspective

BTW, if you're doing a pure e4 app you're likely better off to orient your command implementation towards the DI mechanisms (POJO with @CanExecute and @Execute) methods rather than relying on core expressions since they're created through injection and therefore have access everything in the current context.

Re: Active Perspective Core Expression [message #1221291 is a reply to message #1221040]

Tue, 17 December 2013 05:19

Eclipse User

Eric,

Thanks very much for the direction. However, let's say for Handled Popup Menu Items, if we use @CanExecute rather than Visible-When, this just grays out the menu item instead of totally hiding it. So, I think we cannot achieve the exactly same behaviour.

Also, using @CanExecute means handling this at the command handler level, however, where the required functionality is modifying the visibility of the menu item, this should be handled at a central location regardless of individual handlers I think. So, this is where we need Visible-When. However, I appreciate why you are in favour of POJOs and DI as opposed to using core expressions, so maybe we need a new mechanism to be able to accommodate POJOs as Visible-When handlers. Does that make sense? Either an existing annotation like @CanExecute can be used or a new one (i.e. @IsVisible) can be appointed for this purpose.

I personally feel that current Core Expression definition mechanism is a bit lengthy anyway, so, replacing this with (or extending to) POJOs for Visible-When can also simplify the process.

Regards,

Ozgur.

Re: Active Perspective Core Expression [message #1221444 is a reply to message #1221291]

Tue, 17 December 2013 13:13

Eclipse User

If you want the heuristic to be that the menu / tb item only appears when it's active you could set the model element's 'toBeRendered' flag to whatever value you're going to return from your @CanExecute. I agree though that we might want some more formal pattern for visibility.

The reason we use the complex core expression in the IDE is mostly to allow our menus / tbs and context menus to show the correct state *without* loading / activating any bundles (quite a trick really... Wink

. In most RCP apps this is an unnecessary constraint since they usually have far fewer command contributions and there's no reason not to instantiate the handler itself.

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