Added some improvements.

(1) removed the possible zombie state for the main window;
(2) simplified the window interface accordingly;
(3) guaranteed single window class registration
(4) using `std::make_unique`
(5) substituted asserts with exceptions

Author: PardCode

Tutorial1_Window/Game/main.cpp

@@ -23,10 +23,20 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.*/
 
 #include <OGL3D/Game/OGame.h>
+#include <iostream>
 
 int main()
 {
-	OGame game;
-	game.run();
+	try
+	{
+		OGame game;
+		game.run();
+	}
+	catch (const std::exception& e)
+	{
+		std::cout << "Error: " << e.what() << std::endl;
+		return -1;
+	}
+
 	return 0;
 }

Tutorial1_Window/OGL3D/include/OGL3D/Window/OWindow.h

@@ -29,9 +29,6 @@ class OWindow
 public:
 	OWindow();
 	~OWindow();
-
-	void onDestroy();
-	bool isClosed();
 private:
 	void* m_handle = nullptr;
 };

Tutorial1_Window/OGL3D/source/OGL3D/Game/OGame.cpp

@@ -28,7 +28,7 @@ SOFTWARE.*/
 
 OGame::OGame()
 {
-	m_display = std::unique_ptr<OWindow>(new OWindow());
+	m_display = std::make_unique<OWindow>();
 }
 
 OGame::~OGame()
@@ -37,16 +37,27 @@ OGame::~OGame()
 
 void OGame::run()
 {
-	MSG msg;
-	while (m_isRunning && !m_display->isClosed())
+	
+	while (m_isRunning)
 	{
-		if (PeekMessage(&msg, NULL, NULL, NULL, PM_REMOVE))
+		MSG msg = {};
+		if (PeekMessage(&msg, HWND(), NULL, NULL, PM_REMOVE))
 		{
-			TranslateMessage(&msg);
-			DispatchMessage(&msg);
+			if (msg.message == WM_QUIT)
+			{
+				m_isRunning = false;
+				continue;
+			}
+			else
+			{
+				TranslateMessage(&msg);
+				DispatchMessage(&msg);
+			}
+		}
+		else
+		{
+			Sleep(1);
 		}
-
-		Sleep(1);
 	}
 }
 

Tutorial1_Window/OGL3D/source/OGL3D/Window/OWindow.cpp

@@ -25,19 +25,18 @@ SOFTWARE.*/
 #include <OGL3D/Window/OWindow.h>
 #include <OGL3D/Game/OGame.h>
 #include <Windows.h>
-#include <assert.h>
+#include <stdexcept>
+#include <functional>
 
 LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
 	switch (msg)
 	{
-	case WM_DESTROY:
+	case WM_CLOSE:
 	{
-		OWindow* window = (OWindow *)GetWindowLongPtr(hwnd, GWLP_USERDATA);
-		window->onDestroy();
+		PostQuitMessage(0);
 		break;
 	}
-
 	default:
 		return DefWindowProc(hwnd, msg, wParam, lParam);
 	}
@@ -47,38 +46,35 @@ LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 
 OWindow::OWindow()
 {
-	WNDCLASSEX wc = {};
-	wc.cbSize = sizeof(WNDCLASSEX);
-	wc.lpszClassName = L"OGL3DWindow";
-	wc.lpfnWndProc = &WndProc;
-
-	assert(RegisterClassEx(&wc));
-
+	static const ATOM windowClassId = std::invoke(
+		[]() -> ATOM
+		{
+			WNDCLASSEX wc = {};
+			wc.cbSize = sizeof(WNDCLASSEX);
+			wc.lpszClassName = L"OGL3DWindow";
+			wc.lpfnWndProc = &WndProc;
+			return RegisterClassEx(&wc);
+		}
+	);
+
+	if (!windowClassId) throw std::runtime_error("RegisterClassEx failed");
+	
 	RECT rc = { 0,0,1024,768 };
 	AdjustWindowRect(&rc, WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU, false);
 
-	m_handle = CreateWindowEx(NULL, L"OGL3DWindow", L"PardCode | OpenGL 3D Game", WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU, CW_USEDEFAULT, CW_USEDEFAULT,
-		rc.right - rc.left, rc.bottom - rc.top, NULL, NULL, NULL, NULL);
+	m_handle = CreateWindowEx(NULL, MAKEINTATOM(windowClassId), L"PardCode | OpenGL 3D Game", WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU,
+		CW_USEDEFAULT, CW_USEDEFAULT,
+		rc.right - rc.left, rc.bottom - rc.top, HWND(), HMENU(), HINSTANCE(), NULL);
 
-	assert(m_handle);
+	if (!m_handle) throw std::runtime_error("CreateWindowEx failed");
 
 	SetWindowLongPtr((HWND)m_handle, GWLP_USERDATA, (LONG_PTR)this);
 
-	ShowWindow((HWND)m_handle, SW_SHOW);
-	UpdateWindow((HWND)m_handle);
+	ShowWindow(HWND(m_handle), SW_SHOW);
+	UpdateWindow(HWND(m_handle));
 }
 
 OWindow::~OWindow()
 {
-	DestroyWindow((HWND)m_handle);
-}
-
-void OWindow::onDestroy()
-{
-	m_handle = nullptr;
-}
-
-bool OWindow::isClosed()
-{
-	return !m_handle;
+	DestroyWindow(HWND(m_handle));
 }