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
* The category to which this command belongs. This value should not be
	 * <code>null</code> unless the command is undefined.
	 */
	private Category category = null;
	/**
	 * A collection of objects listening to the execution of this command. This
	 * collection is <code>null</code> if there are no listeners.
	 */
	private transient ListenerList executionListeners = null;
	/**
	 * The handler currently associated with this command. This value may be
	 * <code>null</code> if there is no handler currently.
	 */
	private transient IHandler handler = null;
	/**
	 * The ordered array of parameters understood by this command. This value
	 * may be <code>null</code> if there are no parameters, or if the command
	 * is undefined. It may also be empty.
	 */
	private IParameter[] parameters = null;
	/**
	 * Constructs a new instance of <code>Command</code> based on the given
	 * identifier. When a command is first constructed, it is undefined.
	 * Commands should only be constructed by the <code>CommandManager</code>
	 * to ensure that the identifier remains unique.
	 * 
	 * @param id
	 *            The identifier for the command. This value must not be
	 *            <code>null</code>, and must be unique amongst all commands.
	 */