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
"Cannot get the parameters from an undefined command"); 
		}
		if ((parameters == null) || (parameters.length == 0)) {
			return null;
		}
		final IParameter[] returnValue = new IParameter[parameters.length];
		System.arraycopy(parameters, 0, returnValue, 0, parameters.length);
		return returnValue;
	}
	/**
	 * Returns whether this command has a handler, and whether this handler is
	 * also handled and enabled.
	 * 
	 * @return <code>true</code> if the command is handled; <code>false</code>
	 *         otherwise.
	 */
	public final boolean isEnabled() {
		if (handler == null) {
			return false;
		}
		return handler.isHandled() && handler.isEnabled();
	}
	/**
	 * Returns whether this command has a handler, and whether this handler is
	 * also handled.
	 * 
	 * @return <code>true</code> if the command is handled; <code>false</code>
	 *         otherwise.
	 */
	public final boolean isHandled() {