为什么AfxGetApp能得到我当前进程的CWinApp继承类对象?
例如，我的继承类对象叫做CMyProjectApp: public CWinApp.
难道mfc框架在什么地方去注册了我的类名"CMyProjectApp"或者对象地址，以至于AfxGetApp能否返回记录了的这个实例指针?
感觉很神奇，可是其实现机制是怎么样的，能简单的描述一下么?

[解决办法]
你不是有个theapp的对象么，这个直接返回这个对象就的地址就可以了
[解决办法]
你的程序定义了一个CWinApp的对象，CWinApp的构造函数将this赋值到模块状态中保存起来
每次AfxGetApp从这个地方把this拿出来
[解决办法]

CWinApp::CWinApp(LPCTSTR lpszAppName)
{
if (lpszAppName != NULL)
m_pszAppName = _tcsdup(lpszAppName);
else
m_pszAppName = NULL;

// initialize CWinThread state
AFX_MODULE_STATE* pModuleState = _AFX_CMDTARGET_GETSTATE();
ENSURE(pModuleState);
AFX_MODULE_THREAD_STATE* pThreadState = pModuleState->m_thread;
ENSURE(pThreadState);
ASSERT(AfxGetThread() == NULL);
pThreadState->m_pCurrentWinThread = this;
ASSERT(AfxGetThread() == this);
m_hThread = ::GetCurrentThread();
m_nThreadID = ::GetCurrentThreadId();

// initialize CWinApp state
ASSERT(afxCurrentWinApp == NULL); // only one CWinApp object please
pModuleState->m_pCurrentWinApp = this;
ASSERT(AfxGetApp() == this);

// in non-running state until WinMain
m_hInstance = NULL;
m_hLangResourceDLL = NULL;
m_pszHelpFilePath = NULL;
m_pszProfileName = NULL;
m_pszRegistryKey = NULL;
m_pszExeName = NULL;
m_pRecentFileList = NULL;
m_pDocManager = NULL;
m_atomApp = m_atomSystemTopic = NULL;
m_lpCmdLine = NULL;
m_pCmdInfo = NULL;

// initialize wait cursor state
m_nWaitCursorCount = 0;
m_hcurWaitCursorRestore = NULL;

// initialize current printer state
m_hDevMode = NULL;
m_hDevNames = NULL;
m_nNumPreviewPages = 0;     // not specified (defaults to 1)

// initialize DAO state
m_lpfnDaoTerm = NULL;   // will be set if AfxDaoInit called

// other initialization
m_bHelpMode = FALSE;
m_eHelpType = afxWinHelp;
m_nSafetyPoolSize = 512;        // default size
}

pModuleState->m_pCurrentWinApp = this;