// $Id: ModelCommand.java 12 2010-04-03 00:07:22Z marcusvnac $
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package org.argouml.model;
/**
* A command to record the state of an object before an undoable change.<p>
* The model implementation should create a ModelCommand for any
* undoable operation performed. Any mutator method should normally be
* undoable except loading a model from file.
*
* @author Bob Tarling
*/
public abstract class ModelCommand {
/**
* Execute this command.
* @return any result generated by this command
*/
public abstract Object execute();
/**
* Determine whether the command can be undone.
*
* @return true if the command can be undone
*/
public abstract boolean isUndoable();
/**
* Determine whether the command can be redone once undone.
*
* @return true if the command can be redone
*/
public abstract boolean isRedoable();
/**
* Undo this command.
*/
public abstract void undo();
}