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How to detect when the result of the canExecute-method method has changed on an already open menu [message #1749330]

Mon, 05 December 2016 15:18

Klaus Reger

Messages: 13
Registered: December 2016

Junior Member

Hello everybody,

I have the following question:

A user has opened a menu with the right mouse button, but has not yet made a selection. In the meantime, the canExecute method returns the value false for one of the menu items.
However, the corresponding menu entry in question is not grayed out, and a click on it only calls the canExecute method.

But in this case, I would like to generate a warning message informing the user that the function is no longer available.

How can you do this because the canExecute handler has no indication of the event's trigger?

Thank you very much.

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Re: How to detect when the result of the canExecute-method method has changed on an already open men [message #1752542 is a reply to message #1749330]

Wed, 25 January 2017 00:26

Patrik Suzzi

Messages: 2
Registered: February 2018

Junior Member

@CanExecute is computed at initialization, and when the state changes.
It is not intended to be triggered when your mouse hovers over one menuItem linked to a specific handler.

I suggest you change the label of the related menuItem, instead of displaying a warning.

Below you can see a change in Eclipse code where, at the end of the @Execute method, the commandService is used to change the label of a menu Item:
https://git.eclipse.org/r/#/c/89058/2/bundles/org.eclipse.ui.workbench/Eclipse+UI/org/eclipse/ui/internal/handlers/ToggleStatusBarHandler.java

Regards,
Ing. Patrik Suzzi
Consultant Software Engineer,
Eclipse Platform Committer
https://about.me/psuzzi

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