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/* XLogo4Schools - A Logo Interpreter specialized for use in schools, based on XLogo by Loic Le Coq
* Copyright (C) 2013 Marko Zivkovic
*
* Contact Information: marko88zivkovic at gmail dot com
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version. This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
* Public License for more details. You should have received a copy of the
* GNU General Public License along with this program; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*
*
* This Java source code belongs to XLogo4Schools, written by Marko Zivkovic
* during his Bachelor thesis at the computer science department of ETH Zurich,
* in the year 2013 and/or during future work.
*
* It is a reengineered version of XLogo written by Loic Le Coq, published
* under the GPL License at http://xlogo.tuxfamily.org/
*
* Contents of this file were entirely written Marko Zivkovic
*/
package xlogo.kernel;
/**
* In XLogo, myException was used. My exception was something rather funny.
* Actually it was really bad. myException was an exception that handled itself, by showing an error dialog and by aborting execution of the running Logo program.
* Thus throwing a myException was more like a function call with the side effect, that execution jumped to some other place, wherever it was caught.
* Note that to handle itself, myException had to have a reference to {@link Application}. Thus every part of the interpreter that wanted to throw Logo errors
* had to have such a reference, even though Application was not used otherwise.<br>
* By moving the exception handling at the root, where interpretation is started, in {@link Affichage}, I managed to decouple several classes from Application.
* (Still, many of them are unnecessarily dependent on Application, but I cannot refactor everything in the given time)
*
* Also note how ugly myException was used before. LaunchPrimitive is the best example. The general pattern was this:<br>
*
* <pre>
* {@code
* case i: // i : the id of some Logo primitive
* try
* {
* ...
* if (the next token is not as expected)
* throw new myException(application, errorMessage);
* ...
* }
* catch (myException)
* {}
* break; // => end of execute()
* // Because myException "handled itself", Affichage and Interprete will not continue execution
* }
* </pre>
*
* Note that almost all of the more than 300 Logo primitives contained such a statement, sometimes even more.
* That is more than 5x300 = 1500 unnecessary lines of code (after my style guide) that make the reading very hard,
* and introducing multiple levels of blocks { } to the structure.
*
* I took myself the time to remove all these unnecessary try-catches, place only one in Affichage and thus make the core of the application much more readable.
* <p><p>
* Note that I cannot test all the 300 Logo procedures for every case, but since throwing a myException caused the Interpreter to stop anyway,
* Redirecting the exception up to the root in Affichage will not change the flow of correct Logo Execution. Only executions which caused an exception can maybe behave slightly different now.
* I will for sure test all the procedures that we use in our school projects and a few more.
*
* <p><p>
* Another interesting thing, or again, really bad.
* The {@code static boolean lance} in myException was initialized with false. There are several assignments that set, again, false to it, but there is no single set to true.
* In most cases where lance is tested in a if-statement, it is tested in conjunction with Application.error (which can be true or false)
*
* <p> And then, there was also the nested class Affiche, which was never used.
*
*@author Marko Zivkovic
*/
public class LogoError extends Exception
{
private static final long serialVersionUID = 9184760816698357437L;
public LogoError()
{
}
public LogoError(String st)
{
super(st);
}
}
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