Copyright (c) 2005, 2015 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2005, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/

package org.eclipse.core.commands;


A parameter for a command. A parameter identifies a type of information that
the command might accept. For example, a "Show View" command might accept the
id of a view for display. This parameter also identifies possible values, for
display in the user interface.

Since:
3.1/**
 * <p>
 * A parameter for a command. A parameter identifies a type of information that
 * the command might accept. For example, a "Show View" command might accept the
 * id of a view for display. This parameter also identifies possible values, for
 * display in the user interface.
 * </p>
 *
 * @since 3.1
 */
public interface IParameter {

	
Returns the identifier for this parameter.
Returns:
The identifier; never null./**
	 * Returns the identifier for this parameter.
	 *
	 * @return The identifier; never <code>null</code>.
	 */
	public String getId();

	
Returns the human-readable name for this parameter.
Returns:
The parameter name; never null./**
	 * Returns the human-readable name for this parameter.
	 *
	 * @return The parameter name; never <code>null</code>.
	 */
	public String getName();

	
Returns the values associated with this parameter.
Throws:
ParameterValuesException – 
            If the values can't be retrieved for some reason.
Returns:
The values associated with this parameter. This must not be
        null./**
	 * Returns the values associated with this parameter.
	 *
	 * @return The values associated with this parameter. This must not be
	 *         <code>null</code>.
	 * @throws ParameterValuesException
	 *             If the values can't be retrieved for some reason.
	 */
	public IParameterValues getValues() throws ParameterValuesException;

	
Returns whether parameter is optional. Otherwise, it is required.
Returns:
true if the parameter is optional;
        false if it is required./**
	 * Returns whether parameter is optional. Otherwise, it is required.
	 *
	 * @return <code>true</code> if the parameter is optional;
	 *         <code>false</code> if it is required.
	 */
	public boolean isOptional();
}