http://www.eclipse.org/platform: Commands (Eclipse Foundation) 
Copyright (c) 2006, 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) 2006, 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.operations;

import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IStatus;


Extends IOperationApprover to approve the execution of a particular operation within an operation history. Operations that are candidates for execution have already been validated against their current state and according to the rules of the history. Prior to 3.2, an operation approver was only consulted for undo and redo of an operation, not its initial execution. 

By the time an IOperationApprover2 is consulted, the execution has already
been requested and it has been determined that the operation is valid.
Approvers should return an IStatus object with severity
OK if the operation should proceed, and any other severity if
it should not. When an operation is not approved, it is expected that the
object not allowing the operation has already consulted the user if necessary
or otherwise provided any necessary information to the user about the fact
that the operation is not approved.



 Like IOperationApprover, implementers of this extension must be prepared to receive the approval messages from a background thread. Any UI access occurring inside the implementation must be properly synchronized using the techniques specified by the client's widget library. 


Since:3.2
/**
 * Extends {@link IOperationApprover} to approve the execution of a particular
 * operation within an operation history. Operations that are candidates for
 * execution have already been validated against their current state and
 * according to the rules of the history. Prior to 3.2, an operation approver
 * was only consulted for undo and redo of an operation, not its initial
 * execution.
 * <p>
 * By the time an IOperationApprover2 is consulted, the execution has already
 * been requested and it has been determined that the operation is valid.
 * Approvers should return an <code>IStatus</code> object with severity
 * <code>OK</code> if the operation should proceed, and any other severity if
 * it should not. When an operation is not approved, it is expected that the
 * object not allowing the operation has already consulted the user if necessary
 * or otherwise provided any necessary information to the user about the fact
 * that the operation is not approved.
 * </p>
 * <p>
 * Like {@link IOperationApprover}, implementers of this extension must be
 * prepared to receive the approval messages from a background thread. Any UI
 * access occurring inside the implementation must be properly synchronized
 * using the techniques specified by the client's widget library.
 * </p>
 *
 * @since 3.2
 */
public interface IOperationApprover2 extends IOperationApprover {
	
Return a status indicating whether the specified operation should be
executed. Any status that does not have severity IStatus.OK
will not be approved. Implementers should not assume that the execution
will be performed when the status is OK, since other
operation approvers may veto the execution.

Params:
  • operation – 
           the operation to be executed
  • history – 
           the history performing the execution of the operation
  • info – 
           the IAdaptable (or null) provided by the
           caller in order to supply UI information for prompting the
           user if necessary. When this parameter is not
           null, it should minimally contain an adapter
           for the org.eclipse.swt.widgets.Shell.class. Even if UI
           information is provided, the implementation of this method
           must be prepared for being called from a background thread.
           Any UI access must be properly synchronized using the
           techniques specified by the client's widget library.
Returns:the IStatus describing whether the operation is approved. The
        execution will not proceed if the status severity is not
        OK, and the caller requesting the execution will
        be returned the status that caused the rejection. Any other
        status severities will not be interpreted by the history.
/**
	 * Return a status indicating whether the specified operation should be
	 * executed. Any status that does not have severity <code>IStatus.OK</code>
	 * will not be approved. Implementers should not assume that the execution
	 * will be performed when the status is <code>OK</code>, since other
	 * operation approvers may veto the execution.
	 *
	 * @param operation
	 *            the operation to be executed
	 * @param history
	 *            the history performing the execution of the operation
	 * @param info
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller in order to supply UI information for prompting the
	 *            user if necessary. When this parameter is not
	 *            <code>null</code>, it should minimally contain an adapter
	 *            for the org.eclipse.swt.widgets.Shell.class. Even if UI
	 *            information is provided, the implementation of this method
	 *            must be prepared for being called from a background thread.
	 *            Any UI access must be properly synchronized using the
	 *            techniques specified by the client's widget library.
	 * @return the IStatus describing whether the operation is approved. The
	 *         execution will not proceed if the status severity is not
	 *         <code>OK</code>, and the caller requesting the execution will
	 *         be returned the status that caused the rejection. Any other
	 *         status severities will not be interpreted by the history.
	 */
	IStatus proceedExecuting(IUndoableOperation operation,
			IOperationHistory history, IAdaptable info);
}