Added some explanations about the memory mangement (through eoFunctorStore)
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evomarc
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5 changed files with 266 additions and 86 deletions
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@ -2,23 +2,22 @@
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<meta name="GENERATOR" content="Mozilla/4.75 [en] (X11; U; Linux 2.2.17-21mdk i686) [Netscape]">
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<meta name="GENERATOR" content="Mozilla/4.78 [en] (X11; U; Linux 2.4.7-10 i686) [Netscape]">
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<title>EO Programming guide</title>
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</head>
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<body text="#000000" link="#0000EE" vlink="#551A8B" alink="#FF0000" background="beige009.jpg">
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<b><font color="#CC0000">General: </font></b><a href="eoTutorial.html">Tutorial
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main page </a>-
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<a href="eoTopDown.html">Algorithm-Based</a>
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- <a href="eoBottomUp.html">Component-Based</a>
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- <a href="eoProgramming.html">Programming
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hints</a> - <font face="Arial,Helvetica"><a href="../../doc/html/index.html">EO
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<a href="eoTopDown.html">Algorithm-Based</a> - <a href="eoBottomUp.html">Component-Based</a>
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- <a href="eoProgramming.html">Programming hints</a> - <font face="Arial,Helvetica"><a href="../../doc/html/index.html">EO
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documentation</a></font>
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<br>
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<hr WIDTH="100%"><b><font color="#CC0000">Local: </font></b><a href="#templates">Templates</a>
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-
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<a href="#functors">Functors</a> -
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<a href="#STL">STL Library</a> - <a href="#random">Random
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numbers</a> - <a href="#notations">EO programming style</a>
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numbers</a> - <a href="#notations">EO programming style</a> - <a href="#memory">Memory
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management</a>
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<br>
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<hr WIDTH="100%">
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<center>
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@ -77,11 +76,14 @@ into three derived class. These classes tell you immediately what kind
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of arguments the <b><tt><font color="#993300">operator()</font></tt></b>
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method requires and what kind of result it produces. See <a href="#notations">EO
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conventions</a>, and the <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/classeo_functor_base.html">inheritance
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diagram of class eoFunctorBase</a>.</font></font></b>
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diagram of class eoFunctorBase</a>. </font></font></b> Also note that
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if you create new functors, you should also derive from one of these classes,
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as it is mandatory if you later use the EO <a href="#memory">memory management
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mechanism</a>.
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<br>For a more complete introduction to functors, with detailed discussion,
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go to the <a href="http://www.sgi.com/tech/stl/functors.html">STL
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documentation</a> - as STL also heavily relies on functors, and the eoFunctorBase
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paradigm is borrowed from there.
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go to the <a href="http://www.sgi.com/tech/stl/functors.html">STL documentation</a>
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- as STL also heavily relies on functors, and the eoFunctorBase paradigm
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is borrowed from there.
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<p><b><font color="#FF0000">Functors:</font><font color="#000099"> Example:</font></b>
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<p>The following is a basic example of how to program and use a functor
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object: First code the class:
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@ -372,7 +374,13 @@ myfunction(unsigned </font><font color="#FF6600">_popSize</font><font color="#99
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The initialization parameters of constructors should be named from the
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names of the variables they are used to initialize, e.g.</li>
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<p><br><b><tt><font color="#993300">class eoMyClass</font></tt></b>
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<br>
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<p>
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<br>
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<br>
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<br>
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<br>
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<p><b><tt><font color="#993300">class eoMyClass</font></tt></b>
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<br><b><tt><font color="#993300">{</font></tt></b>
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<br><b><tt><font color="#993300">public:</font></tt></b>
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<br><b><tt><font color="#993300"> eoMyClass(unsigned _popSize):</font><font color="#FF6600">popSize(_popSize)</font><font color="#993300">{...}</font></tt></b>
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@ -396,18 +404,91 @@ or <b><font face="Arial,Helvetica"><font size=+1><a href="../../doc/html/c
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Blabla</li>
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</ul>
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<hr WIDTH="100%">
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<br><a NAME="memory"></a><b><font color="#000099"><font size=+1>EO memory
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management</font></font></b>
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<p>Most of EO constructs are based on the <b><font color="#FF6600">encapsulation</font></b>
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of objects into other objects, and the embedded objects are passed through
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the constructor of the embedding object.
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<br>For instance, the construction of an algorithm requires a breeder (plus
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many other things of course), the construction of a breeder usually requires
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a selector, and in turn the construction of a selector requires some parameters.
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This gives something resembling the following
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<p><b><tt><font color="#993300">eoTournamentSelection<EOT> select(tSize);</font></tt></b>
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<br><b><tt><font color="#993300">eoBreeder<EOT> breed(select);</font></tt></b>
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<br><b><tt><font color="#993300">eoEasyAlgo<EOT> algo( ..., breed, ...);</font></tt></b>
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<p>Such a practice is no problem when doing <b><font color="#FF6600">everything
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in a (large!) main function</font></b>: all objects are local to that function,
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but when the end of the function is also the end of the program. For instance,
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all programs in <a href="eoLesson1.html">Lesson1</a>, <a href="eoLesson2.html">Lesson2</a>
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and <a href="eoLesson3.html">Lesson3</a> of this tutorial are built that
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way.
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<p>It is however a big problem when you want to outsource some code in
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other functions: indeed, the above sequence create objects that <b><font color="#FF6600">dissapear</font></b>
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when exiting the function, and thus cannot be used outside their defining
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function.
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<p>The solution is of course to use <b><font color="#FF6600">pointers</font></b>,
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which gives something like
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<p><b><tt><font color="#993300">eoTournamentSelection<EOT> *ptSelect
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= new eoTournamentSelection<EOT>(tSize);</font></tt></b>
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<br><b><tt><font color="#993300">eoBreeder<EOT> *ptBreed = new eoBreeder<EOT>(select);</font></tt></b>
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<br><b><tt><font color="#993300">eoEasyAlgo<EOT> *ptAlgo = new eoEasyAlgo<EOT>(
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..., breed, ...);</font></tt></b>
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<p>and you can then use the dynamically allocated objects anywhere. But
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the trouble with such a construct is that after exiting the function where
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such objects are defined, <b><font color="#FF6600">you will never be able
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to free</font></b> this allocated memory, should you not need the objects
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any nore. Whereas this is not in general a big problem (except of being
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a very bad practice that will make you a very naughty programmer :-), it
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will prevent any re-entrance of the resulting code, and for instance you
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will not be able to use an evolutionary algorithm within another loop of
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some outside code.
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<p>The solution in EO us to use an <b><tt><font color="#993300"><font size=+1><a href="../../doc/html/classeo_functor_store.html">eoFunctorStore</a></font></font></tt></b>
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object to store such nowhere-belonging pointers: whenever you allocate
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such a thing, store it into an eoState : deleting that state will delete
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all the stored pointers - one eoState is thus the only object you have
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to care of.
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<p>The above pointera llocation sequence thus become
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<p><b><tt><font color="#993300">eoTournamentSelection<EOT> *ptSelect
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= new eoTournamentSelection<EOT>(tSize);</font></tt></b>
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<br><b><tt><font color="#993300">state.storeFunctor(ptSelect);</font></tt></b>
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<br><b><tt><font color="#993300">eoBreeder<EOT> *ptBreed = new eoBreeder<EOT>(select);</font></tt></b>
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<br><b><tt><font color="#993300">state.storeFunctor(ptBreed);</font></tt></b>
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<br><b><tt><font color="#993300">eoEasyAlgo<EOT> *ptAlgo = new eoEasyAlgo<EOT>(
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..., breed, ...);</font></tt></b>
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<br><b><tt><font color="#993300">state.storeFunctor(ptAlgo);</font></tt></b>
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<p>or, even more quickly (though less readably)
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<p><b><tt><font color="#993300">eoTournamentSelection<EOT> *ptSelect
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=</font></tt></b>
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<br><b><tt><font color="#993300">
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state.storeFunctor(new eoTournamentSelection<EOT>(tSize));</font></tt></b>
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<br><b><tt><font color="#993300">eoBreeder<EOT> *ptBreed =</font></tt></b>
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<br><b><tt><font color="#993300">
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state.storeFunctor(new eoBreeder<EOT>(select));</font></tt></b>
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<br><b><tt><font color="#993300">eoEasyAlgo<EOT> *ptAlgo =</font></tt></b>
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<br><b><tt><font color="#993300">
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state.storeFunctor(new eoEasyAlgo<EOT>( ..., breed, ...));</font></tt></b>
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<p>In both the above code, state is an <b><tt><font color="#993300"><font size=+1>eoFunctorStore</font></font></tt></b>
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that is of course <b><font color="#FF6600">passed from outside the function</font></b>
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- and it's called state because in most cases it will actually be an eoState.
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As its name says, an <b><tt><font color="#993300"><font size=+1>eoFunctorStore</font></font></tt></b>
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can store any object that is an (derives from) <b><tt><font size=+1><a href="../../doc/html/classeo_functor_base.html">eoFunctorBase</a></font></tt></b>
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- hence all objects in EO that are used as functors should derive from
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either <a href="#functors">eoF, eoUF or eBF</a>.
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<p>Examples of such constructs are shown in the make_xxx files described
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in <a href="eoLesson4.html">Lesson4</a>.
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<br>
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<hr WIDTH="100%"><b><font color="#CC0000">Local: </font></b><a href="#templates">Templates</a>
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-
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<a href="#functors">Functors</a> -
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<a href="#STL">STL Library</a> - <a href="#random">Random
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numbers</a> - <a href="#notations">EO programming style</a>
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numbers</a> - <a href="#notations">EO programming style</a> - <a href="#memory">Memory
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management</a>
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<br>
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<hr WIDTH="100%">
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<br><b><font color="#CC0000">General: </font></b><a href="eoTutorial.html">Tutorial
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main page </a>- <a href="eoTopDown.html">Algorithm-Based</a>
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- <a href="eoBottomUp.html">Component-Based</a>
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- <a href="eoProgramming.html">Programming
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hints</a> - <font face="Arial,Helvetica"><a href="../../doc/html/index.html">EO
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main page </a>- <a href="eoTopDown.html">Algorithm-Based</a> - <a href="eoBottomUp.html">Component-Based</a>
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- <a href="eoProgramming.html">Programming hints</a> - <font face="Arial,Helvetica"><a href="../../doc/html/index.html">EO
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documentation</a></font>
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<br>
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<hr>
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