Framework Design Principle

Frameworks must be designed starting from a set of usage scenarios and code samples implementing these scenarios.

RegistryKey key = Registry.CurrentUser.OpenSubKey("Software\Microsoft\Windows\CurrentVersion\Run");
key.AddValue("notepad.exe", "%windir%\notepad.exe");

class Key
{
public:
Key(HKEY root, LPCTSTR path, DWORD desired_access = MAXIMUM_ALLOWED);
~Key();
operator HKEY();
};

class KeyReader : protected Key
{
public:
KeyReader(HKEY root, LPCTSTR path, DWORD desired_access = GENERIC_READ);
bool ReadValue(LPTSTR name, DWORD &value);
};

class KeyReadWriter : protected KeyReader
{
public:
KeyReadWriter(HKEY root, LPCTSTR path, DWORD desired_access = GENERIC_READ|GENERIC_WRITE);
bool WriteValue(LPTSTR name, DWORD value);
bool DeleteValue(LPTSTR name);
};

DWORD Version;

try
{
    reg_key Key(HKEY_LOCAL_MACHINE, L"SOFTWARE\\MyProgram");
    Version = Key.read(L"Version");
}

catch (std::exception &Exc)
{
    ...
}

BOOL
GetVersion(
    __inout DWORD      * pVersion
    )
HKEY hKey;

if (ERROR_SUCCESS != RegOpenKeyExW(HKEY_LOCAL_MACHINE,
    L"SOFTWARE\\MyProgram",
    NULL,
    KEY_READ,
    &hKey))
{
    return FALSE;
}

DWORD cbVersion(sizeof (DWORD));
DWORD fType;

if (ERROR_SUCCESS != RegQueryValueExW(hKey,
    L"Version",
    NULL,
    &fType,
    pVersion,
    &cbVersion))
{
    RegCloseKey(hKey);
    return FALSE;
}

RegCloseKey(hKey);

if (REG_DWORD != fType)
{
    return FALSE;
}

return TRUE
}

O>DWORD Version;

O>try
O>{
O>    reg_key Key(HKEY_LOCAL_MACHINE, L"SOFTWARE\\MyProgram");
O>    Version = Key.read(L"Version");
O>}

O>

BOOL GetVersion(__inout DWORD      * pVersion)
{
    HKEY hKey; HRESULT hr; 
    DWORD fType, cbVersion = sizeof (DWORD);

    if (S_OK == (hr = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
                                L"SOFTWARE\\MyProgram",
                                NULL,
                                KEY_READ,
                                &hKey)))
    {
        hr = RegQueryValueExW(hKey,
                                        L"Version",
                                        NULL,
                                        &fType,
                                        (LPBYTE)pVersion,
                                        &cbVersion);
        if (REG_DWORD != fType) hr = E_FAIL;
        RegCloseKey(hKey);
    }
    return S_OK == hr?TRUE:FALSE;
}

• обертка над системными функциями
  
• абстракция от операционной системы (для портабельности или юнит-тестированности других модулей, к примеру)

Registry
{
  Key ReadKey(..)
}

RegistryInfoNotifier
{
  SendRegistryKeyOverEmail(Key, email)
}