com.wandrell.pattern.command.UndoableCommand Maven / Gradle / Ivy
/**
* The MIT License (MIT)
*
* Copyright (c) 2015 the original author or authors.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.wandrell.pattern.command;
/**
* Extension of {@link Command} which allows reversing the process done during
* the execution.
*
* This is done calling the {@link #undo() undo} method after the
* {@link #execute() execute} method call. Note that if any exception is caused
* by the undoing it is expected to be let spread out of the method, and not be
* caught inside.
*
* Note that if the command's execution has caused an exception, then it may not
* be possible to undo it.
*
* Also, if the command has not been executed, then undoing it is expected to do
* nothing.
*
* A simple example of this procedure would be a command which during it's
* execution adds a 1 to a number it stores. Undoing the command would subtract
* 1 from said stored number.
*
* @author Bernardo Martínez Garrido
*/
public interface UndoableCommand extends Command {
/**
* Undoes the work done during the execution.
*
* If the {@code Command} has not been executed when this method is called
* then this call is expected to do nothing at all.
*
* If any error has occurred during the execution, then it may not be
* possible to undo the command's execution.
*
* Also, if the command has not been executed undoing it is expected to do
* nothing.
*
* @throws Exception
* when any exception is thrown during the undoing
*/
public void undo() throws Exception;
}