Eclipse RCP: Conditionally enabling/disabling perspective in Perspectie Switcher - eclipse-rcp

Question

The Open Perspective View shows a list of perspectives to which a user can switch. My custom perspective is there, too. Can I have it not listed or greyed out, if a certain condition bis not met?
The second best alternative that comes to my mind is to have it listed, but the actual switch is not carried out, if b == false.

Answer 1

The best way for me was to use the extension point org.eclipse.ui.activities, as greg-449 suggested, and add a propertyTester. In order to hide perspective related UI elements and not every UI element from the same plugin, one can use isEqualityPattern="true".
<extension point="org.eclipse.ui.activities">
<activity
description="Remove some UI Elements"
id="com.my.plugin.ui.hideUI"
name="HideUI">
<enabledWhen>
<test
forcePluginActivation="false"
property="com.my.plugin.ui.PlanningPropertyTester">
</test>
</enabledWhen>
</activity>
<activityPatternBinding
activityId="com.btc.edm.hidePlanning"
isEqualityPattern="true"
pattern="com.my.plugin.ui/id.of.the.perspective.to.hide">
</activityPatternBinding>
</extension>
<extension
point="org.eclipse.core.expressions.propertyTesters">
<propertyTester
class="com.my.plugin.ui.MyPropertyTester"
id="com.my.plugin.ui.propertyTester"
namespace="com.my.plugin.ui"
properties="MyPropertyTester"
type="java.lang.Object">
</propertyTester>
</extension>
It is important to have a fully qualified name for type.
The MyPropertyTester class extends org.eclipse.core.expressions.PropertyTester and overrides the test method.
public class MyPropertyTester extends PropertyTester {
#Override
public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
if (goodWeather()) {
return true;
return false;
}
}