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Reusing a propertyTester outside expressions [message #333264]

Tue, 02 December 2008 16:44

Stefan Winkler

Messages: 307
Registered: July 2009
Location: Germany

Senior Member

Hi,

is there a way / a common pattern for the following scenario:

I have defined a (EMF-)Object (basically a Bean with several getters and
setters).
Also I have defined a propertyTester which evaluates several of the
bean's properties and then returns a derived flag depending on the
properties' values. This works nicely if the propertyTester is used in
command handler enablement expressions.

Now I want to create a view including a TableViewer which lists several
of those objects and I want to use an italic font, if the propertyTester
evaluates to true. So far, I have duplicated the evaluation code for the
tester to the LabelProvider of the TableViewer to return the appropriate
font. I just wondered, if there is a way of calling the propertyTester
instead, such that I could write

public Font getFont(Object element) {
if ( callToPropertyTester(element) ) {
return italicFont;
}
return JFaceResources.getDefaultFont();
}

Thanks for any hint.

Cheers,
Stefan

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Re: Reusing a propertyTester outside expressions [message #333296 is a reply to message #333264]

Wed, 03 December 2008 15:29

Paul Webster

Messages: 6859
Registered: July 2009
Location: Ottawa

Senior Member

If you provide the property tester, you could simply do a new
MyPT().test(object, other, information)

(caching the MyPT instance if necessary).

To use it the exact same way as used in the IEvaluationService, you
would have to do something like RegistryPageContributor. Check out:

org.eclipse.ui.internal.dialogs.RegistryPageContributor.init ializeEnablement(IConfigurationElement)
org.eclipse.ui.internal.dialogs.RegistryPageContributor.fail sEnablement(Object)

Property testers are not generally provided as part of the programmatic
expressions API because you can simply write a subclass of
org.eclipse.core.expressions.Expression

PW

--
Paul Webster
http://wiki.eclipse.org/Platform_Command_Framework
http://wiki.eclipse.org/Command_Core_Expressions
http://wiki.eclipse.org/Menu_Contributions
http://wiki.eclipse.org/Menus_Extension_Mapping
http://help.eclipse.org/ganymede/index.jsp?topic=/org.eclips e.platform.doc.isv/guide/workbench.htm

Paul Webster
http://wiki.eclipse.org/Platform_Command_Framework
http://wiki.eclipse.org/Command_Core_Expressions
http://wiki.eclipse.org/Menu_Contributions

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