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
* </p>
	 * <p>
	 * Notification is sent to all listeners that something has changed.
	 * </p>
	 * 
	 * @param name
	 *            The name of this command; must not be <code>null</code>.
	 * @param description
	 *            The description for this command; may be <code>null</code>.
	 * @param category
	 *            The category for this command; must not be <code>null</code>.
	 * @param parameters
	 *            The parameters understood by this command. This value may be
	 *            either <code>null</code> or empty if the command does not
	 *            accept parameters.
	 */
	public final void define(final String name, final String description,
			final Category category, final IParameter[] parameters) {
		if (name == null) {
			throw new NullPointerException(
					"The name of a command cannot be null"); 
		}
		if (category == null) {
			throw new NullPointerException(
					"The category of a command cannot be null"); 
		}
		final boolean definedChanged = !this.defined;
		this.defined = true;
		final boolean nameChanged = !Util.equals(this.name, name);
		this.name = name;