Game Development -

Service Locator

In game development, service locator is the library that offers access to resources outside a single game object.

class Locator
{
public:
    static void initialize()
    {
        service_ = &nullService_;
    }
    static Audio& getAudioService()
    {
        assert(service != NULL);
        return *service_;
    }
    static void setAudioService(Audio* service)
    {
        if (service == NULL)
        {
            // Revert to null service.
            service_ = &nullService_;
        }
        else
        {
            service_ = service;
        }
    }

private:
    static Audio* service_;
    static NullAudio nullService_;
};

class Audio
{
public:
    virtual ~Audio() {}
    virtual void playSound(int soundID) = 0;
    virtual void stopSound(int soundID) = 0;
    virtual void stopAllSounds() = 0;
};

class ConsoleAudio : public Audio
{
public:
    virtual void playSound(int soundID)
    {
        // Play sound using console audio api...
    }

    virtual void stopSound(int soundID)
    {
        // Stop sound using console audio api...
    }

    virtual void stopAllSounds()
    {
        // Stop all sounds using console audio api...
    }
};

class NullAudio: public Audio
{
public:
    virtual void playSound(int soundID) { /* Do nothing. */ }
    virtual void stopSound(int soundID) { /* Do nothing. */ }
    virtual void stopAllSounds()        { /* Do nothing. */ }
};