Question

I am a hobbyist C++ programmer and currently working on a game (using Ogre3D) and I have a question regarding the memory allocation for my main classes.

I have read a lot on memory allocation, allocating automatically on the stack and dynamically on the heap, and their differences (performance, limited stack size). Still I am not sure what to use for my main class (Application) and some other ‘factory’ classes (created by a single instance of the Application class), which will all have a single instance existing throughout the entire execution.

Below is a simplified snippet of the layout:

int main() 
{
    // like this (automatic)
    Application app;
    app.create();    // initializing
    app.run();       // runs the game-loop

    // or like this (dynamic)
    Application* app;
    app = new Application();
    app->create();
    app->run();

    return(0);       // only reached after exiting game
}



class Application
{
public:
    Application();   // ctor
    ~Application();  // dtor

    // like this, using 'new' in ctor and 'delete' in dtor (dynamic)
    SceneManager* sceneManager_;   // a factory for handling scene objects
    DebugManager* debugManager_;   // a factory for handling debugging objects

    // or like this (automatic)
    SceneManager sceneManager_;
    DebugManager debugManager_;
};

Is it better to allocate memory on the stack or on the heap (both for the Application class and the factory classes)? And by what arguments?

Thanks in advance!

Answer 1

Always prefer automatic allocation over dynamic allocation. And when you need dynamic allocation, make sure its lifetime is managed by automatically allocated resource wrappers, like smart pointers.