Execute class code once C++ - c++

Question

I am trying to use sdl as a window manager for openGL. I looked into using Windows native API, but looked to confusing.
With that being said, I have a class Window which I would like to wrap all the SDL stuff in for my windows management right now. Figure it will let me swap out windows management later if I find I do not want to use SDL.
I am guessing that a lot of openGL initialization code only needs to be run one time.
if(SDL_Init(SDL_INIT_EVERYTHING) < 0 ) {
exit(0x1);
}
SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
SDL_GL_SetAttribute(SDL_GL_BUFFER_SIZE, 32);
SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 8);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 2);
Then in the class constructor I can create the window with
Window::Window(int winW, int winH) {
if((Surf_Display = SDL_SetVideoMode(winW,winH,32, SDL_HWSURFACE | SDL_GL_DOUBLEBUFFER | SDL_OPENGL | SDL_RESIZABLE )) == NULL) {
exit(2);
}
glClearColor(0, 0, 0, 0);
glClearDepth(1.0f);
glViewport(0, 0, winW, winH);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, winW, winH, 0, 1, -1);
glMatrixMode(GL_MODELVIEW);
glEnable (GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glLoadIdentity();
}
I'm just not sure how to go about doing this. If I put the code before I define the class in the header, does this achieve the desired result?
;init code
;class window { };

Answer 1

The simplest thing would be to put that initialisation code into a function and the to just call this function from main:
/* header */
void init_window_management (void);
/* some source file */
void init_window_management (void) {
// your code
}
/* main file */
// ... also include that header ...
int main(int argc, char ** argv) {
// ...
init_window_management();
// ... use instances of the window class
}
Then there's also std::call_once.
If I put the code before I define the class in the header, does this achieve the desired result?
No. A header is for function and class declarations. Code to execute lives in (member) functions, these are then called (ultimately) via the main function.