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<p><a class='wikilink' href='../Main/HomePage.html'>Main</a> > <span class='wikitrail'><a class='wikilink' href='Main.html'>Reference Manual</a> > <a class='wikilink' href='Developer.html'>Information for developers</a> > <a class='selflink' href='DeveloperExtend.html'>Extension modules</a></span>
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<p class='vspace'>FrePPLe is designed as an extendable framework.<br />Additional modeling and solver modules can be loaded at runtime without recompiling the library.<br />Such extension modules can be shipped with frePPLe, or can be developed by third parties. Modules can be open source or have a commercial license.
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<p class='vspace'>An simple example is available in the testcase <a class='wikilink' href='TestSampleModule.html'>sample_module</a>.<br />FrePPLe currently includes three examples of such extension modules: a module implementing a python interpreter, a forecast class implementing a special type of demand, and a solver using a linear programming algorithm.
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<p class='vspace'>The steps below define how a custom extension can be build on the framework.
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<div class='vspace'></div><ul><li>The proper way to build extension is by creating modules.<br /> Other ways of extending the package may technically be possible, but are not recommended.<br /> Copying the code and header structure from an existing module is the quickest and easiest start.
<div class='vspace'></div></li><li>Create your own header files, and include the frePPLe header file planner.h to have access to the frePPLe objects.<br /> A simple header file can look like this:
</li></ul><div class='vspace'></div><pre> #include "frepple.h"
using namespace frepple;
namespace your_module
{
MODULE_EXPORT const char* initialize(
const CommandLoadLibrary::ParameterList& z
);
...
your classes and function definitons
...
}
</pre><div class='vspace'></div><ul><li>Create your own C++ implementation files, which will include your customized header file.<br /> It is important is to include an initialize() method, and use it to register your extension in the frePPLe framework. The method is automatically called when the module is loaded.
</li></ul><div class='vspace'></div><pre> #include "your_module.h"
namespace your_module
{
MODULE_EXPORT const char* initialize(
const CommandLoadLibrary::ParameterList& z
)
{
...
your initialization code goes here
...
}
your method and class implementations go here
</pre><div class='vspace'></div><ul><li>Compile your code as a loadable module.<br /> The command line options and arguments vary for each compiler and platform. For gcc I use the options
"-module -shrext .so -avoid-version", adding also "-no-undefined" when running under Cygwin.<br /> To keep things simple and transparant please use the .so extension for you modules and place them in the $FREPPLE_HOME directory.
<div class='vspace'></div></li><li>Update the init.xml or init.py file to load your module with the "frepple.loadmodule" Python function.<br /> Keyword arguments to this function are passed to the initialize() funtion when the module is loaded.
<div class='vspace'></div></li><li>Update the file frepple.xsd by defining the XML constructs enabled by your module.<br /> To keep things clean and modular, it is recommended to do this by including a seperate xsd file rather than directly entering the definition in the file.
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