error_with_exceptions.d

import core.sys.windows.windows;
import std.utf : toUTFz;
import std.stdio: writeln;

int main() {
    writeln("start");
    try {
        WinThing meh = new WinThing();
    } catch(Exception e) {
        writeln("error");
    }
    writeln("end");
    return 0;
}

class WinThing {
    private static string BASE_CLASS = "BaseClass";
    private static WinThing*[HWND] winMap;
    private HWND hwnd;

    static this() {
        WNDCLASSEX wc;

        wc.style         = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
        wc.lpfnWndProc   = &WndProc;
        wc.cbClsExtra    = 0;
        wc.cbWndExtra    = 0;
        wc.hInstance     = GetModuleHandle(NULL);
        wc.hIcon         = LoadIcon(NULL, IDI_WINLOGO);
        wc.hIconSm       = wc.hIcon;
        wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
        wc.hbrBackground = cast(HBRUSH)GetStockObject(BLACK_BRUSH);
        wc.lpszMenuName  = NULL;
        wc.lpszClassName = toUTFz!(const wchar*)(BASE_CLASS);
        wc.cbSize        = WNDCLASSEX.sizeof;

        if(!RegisterClassEx(&wc)) {
            writeln("Could not register new windows class.");
            return;
        }
    }

    extern(Windows)
    static LRESULT WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) nothrow {
        WinThing* window = null;

        try {
            if (msg == WM_CREATE) {
                
                // pointer passed into createWindowEx can be obtained from the create struct
                CREATESTRUCT* createStruct = cast(CREATESTRUCT*) lparam;

                // store pointer to window in lookup map
                window = cast(WinThing*)((*createStruct).lpCreateParams);
                winMap[hwnd] = window;
            } else {
                // all messages, fetch window and invoke instance specific handler
                window = winMap[hwnd];
            }
        } catch(Exception e) {
        }

        // return (*window).handleMessage(hwnd, msg, wparam, lparam);

        return DefWindowProc(hwnd, msg, wparam, lparam);
    }

    this() {
        // pass the pointer to this class to create window ex
        hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, toUTFz!(const wchar*)(BASE_CLASS), "Test Window", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 800, 800, NULL, NULL, GetModuleHandle(NULL), cast(void*)this);
        if(hwnd == NULL) {
            writeln("Could not create window.");
            return;
        }

        ShowWindow(hwnd, SW_SHOW);
        UpdateWindow(hwnd);
    }

    public LRESULT handleMessage(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
        // instance specific things...
        return DefWindowProc(hwnd, msg, wparam, lparam);
    }
}