Singleton.h File Reference

Definition of the Singleton template that is used as base class for classes that allow only one instance. More...

#include "UtilPrereqs.h"
#include <cstring>
#include <typeinfo>
#include "OrxAssert.h"

Go to the source code of this file.

Classes
class	orxonox::Singleton< T >
	Base for singleton classes. More...

Namespaces
	orxonox
	Die Wagnis Klasse hat die folgenden Aufgaben:

Detailed Description

Definition of the Singleton template that is used as base class for classes that allow only one instance.

Classes that inherit from orxonox::Singleton follow the singleton pattern and thus allow only one instance of the class to exist. This istance is stored in a static variable called singletonPtr_s. orxonox::Singleton will access this variable, but it must be implemented in the deriving class.

Example:

class TestSingleton : public Singleton<TestSingleton>   // inherit from Singleton, pass the own class as template argument
{
    friend class Singleton<TestSingleton>;              // friend declaration so Singleton can access singletonPtr_s

    public:
        TestSingleton();                                // public constructor because we may want to manage this singleton
                                                        //     with an orxonox::ScopedSingletonWrapper
        virtual ~TestSingleton();                       // public destructor

        void testFunction();                            // put your functions here

    private:
        int testValue_;                                 // put your variables here

        static TestSingleton* singletonPtr_s;           // static singleton instance pointer, used by the Singleton template
};

And don't forget to initialize the static singleton pointer in the source (*.cc) file:

TestSingleton* TestSingleton::singletonPtr_s = nullptr;

If a class inherits from orxonox::Singleton, it also inherits its functions. The most important function is orxonox::Singleton::getInstance() which returns a reference to the only instance of the singleton.

Example:

TestSingleton::TestSingleton()                          // implement the constructor
{
    this->testValue_ = 15;
}

void TestSingleton::testFunction()                      // implement testFunction
{
    orxout() << "My value is " << this->testValue_ << endl;
}

TestSingleton::getInstance().testFunction();            // prints "My value is 15"