/*******************************************************************************
* Copyright (c) 2006 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* 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 {@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 <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);
}
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