The RFModule Class

In this tutorial we show more details of how to write an iCub module using the module helper class.

Introduction

In a previous tutorial we showed how to use the ResourceFinder to organize modules parameters in $YARP_DATA_HOME/contexts.

The RFModule helper class simplify writing an iCub module that uses the ResourceFinder class.

This is how a module will look like:

#include <iostream>
#include <iomanip>
 
#include <yarp/os/Network.h>
#include <yarp/os/RFModule.h>
 
using namespace std;
using namespace yarp::os;
 
class MyModule:public RFModule
{
    Port handlerPort; // a port to handle messages
    int count;
public:
 
    double getPeriod()
    {
        /* module periodicity (seconds), called implicitly by the module. */
        return 1.0;
    }
 
    /* This is our main function. Will be called periodically every getPeriod() seconds */
    bool updateModule()
    {
        count++;
        cout<<"["<<count<<"]"<< " updateModule... "<<endl;
 
        return true;
    }
 
 
    /* Message handler. Just echo all received messages. */
    bool respond(const Bottle& command, Bottle& reply)
    {
        cout<<"Got something, echo is on"<<endl;
        if (command.get(0).asString()=="quit")
            return false;
        else
            reply=command;
        return true;
    }
 
 
    /* Configure function. Receive a previously initialized
       resource finder object. Use it to configure your module.
       If you are migrating from the old module, this is the function
       equivalent to the "open" method. */
    bool configure(yarp::os::ResourceFinder &rf)
    {
        count=0;
        /* optional, attach a port to the module
           so that messages received from the port are redirected
           to the respond method */
        handlerPort.open("/myModule");
        attach(handlerPort);
        return true;
    }
 
    // Interrupt function.
    bool interruptModule()
    {
        cout<<"Interrupting your module, for port cleanup"<<endl;
        return true;
    }
 
    /* Close function, to perform cleanup. */
    bool close()
    {
        /* optional, close port explicitly */
        cout<<"Calling close function\n";
        handlerPort.close();
      return true;
    }
};

and this is the main function to instantiate it.

int main(int argc, char * argv[])
{
    /* initialize yarp network */
    Network yarp;
 
    /* create your module */
    MyModule module;
 
    /* prepare and configure the resource finder */
    ResourceFinder rf;
    rf.configure(argc, argv);
    rf.setVerbose(true);
 
    cout << "Configuring and starting module. \n";
    module.runModule(rf);   // This calls configure(rf) and, upon success, the module execution begins with a call to updateModule()
 
    cout<<"Main returning..."<<endl;
 
    return 0;
}

Code

See code in: src/module/tutorial_module.cpp