Bug 121709 [Commands] parameters: Add types
I'm going to attach a patch that adds support for typed command parameters. This addresses several issues: - parameter values are strings, but handlers may want to work on objects - multiple handlers of a command should have a consistent way of converting string parameter values to objects - tooling to construct parameterized commands that starts with object parameter values needs a way of producing string parameter values that will work when the command is executed - there should be a way to classify commands by their object parameter types so, given an object, a set of commands that may work with it can be suggested To address these issues, the patch allows parameter types to be declared in the extension-point XML. The example below defines a command for negating integers and a parameter type that works with it. <extension point="org.eclipse.ui.commands"> <command id="org.example.commands.negateInteger" defaultHandler="org.example.commands.NegateIntegerHandler" name="Negate an Integer"> <commandParameter id="param" name="the param" optional="false" typeId="org.example.commands.Integer"/> </command> <commandParameterType id="org.example.commands.Integer" converter="org.example.commands.IntegerConverter" type="java.lang.Integer"/> </extension> In addition to extending the schema for org.eclipse.ui.commands, code has been added to a number of plugins (primarily org.eclipse.core.commands) to support the notion of typed parameters.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
final NotEnabledException exception = new NotEnabledException(
						"Trying to execute a disabled command"); 
				fireNotEnabled(exception);
				throw exception;
			}
			
			try {
				final Object returnValue = handler.execute(event);
				firePostExecuteSuccess(returnValue);
				return returnValue;
			} catch (final ExecutionException e) {
				firePostExecuteFailure(e);
				throw e;
			}
		}
		final NotHandledException e = new NotHandledException(
				"There is no handler to execute."); 
		fireNotHandled(e);
		throw e;
	}
	/**
	 * Notifies the listeners for this command that it has changed in some way.
	 * 
	 * @param commandEvent
	 *            The event to send to all of the listener; must not be
	 *            <code>null</code>.
	 */
	private final void fireCommandChanged(final CommandEvent commandEvent) {
		if (commandEvent == null) {
			throw new NullPointerException("Cannot fire a null event");