Question

How to catch an exception thrown by the static object a in the pseudo-code below, where WndProc() is the standard message processing function in the Win32 API ?

class A
{
    public:
    class Exception{};
    A() throw(Exception) { ... }
};

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, UINT wParam, LONG lParam)
{
    static A a;

    switch( message )
    {
        case WM_CREATE:

        ...

        break;

        ...

        default:

        return DefWindowProc(hwnd, message, wParam, lParam);
    }
    return 0;
}

Answer 1

Use a static pointer, initialized to NULL, and create the class instance when WM_CREATE is called.

Of course, for any message other than WM_CREATE, if you will be using the instance you should double-check that the pointer is not NULL – just in case you’re getting messages in an unexpected order.