Windows API и COM

// Проследите фактическое поведение HandleOwner.
program HandleOwner;
uses Winapi.Windows, System.SysUtils;
var H: THandle;
begin
  H := CreateFile('data.bin', GENERIC_READ, FILE_SHARE_READ, nil,
    OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if H = INVALID_HANDLE_VALUE then
    RaiseLastOSError;
  try
    Writeln('opened');
  finally
    CloseHandle(H);
  end;
end.

// Проследите фактическое поведение ComGateway.
unit ComGateway;
interface
type
  ISpreadsheetGateway = interface
    procedure ExportRows(const FileName: string);
  end;
implementation
uses System.Win.ComObj, Winapi.ActiveX;
end.

// Платформенный вызов изолирован, а полученный HANDLE проверяется и закрывается.
program WinApiAdapter;
{$APPTYPE CONSOLE}
uses System.SysUtils, Winapi.Windows, Winapi.ShellAPI;
type
  IProcessLauncher = interface
    function Launch(const FileName, Args: string): Cardinal;
  end;
  TWindowsProcessLauncher = class(TInterfacedObject, IProcessLauncher)
    function Launch(const FileName, Args: string): Cardinal;
  end;
function TWindowsProcessLauncher.Launch(const FileName, Args: string): Cardinal;
var
  Info: TShellExecuteInfo;
begin
  FillChar(Info, SizeOf(Info), 0);
  Info.cbSize := SizeOf(Info);
  Info.fMask := SEE_MASK_NOCLOSEPROCESS;
  Info.lpFile := PChar(FileName);
  Info.lpParameters := PChar(Args);
  if not ShellExecuteEx(@Info) then
    RaiseLastOSError;
  if Info.hProcess = 0 then
    raise EInvalidOpException.Create('process handle was not returned');
  try
    Result := GetProcessId(Info.hProcess);
    if Result = 0 then
      RaiseLastOSError;
  finally
    CloseHandle(Info.hProcess);
  end;
end;
begin
end.

// Проследите фактическое поведение ComAcrossThreads.
program ComAcrossThreads;
uses System.Win.ComObj;
var Excel: OleVariant;
procedure CreateExcel;
begin
  Excel := CreateOleObject('Excel.Application');
end;
procedure Worker;
begin
  Excel.Workbooks.Add;
end;
begin end.

// Отделите правило языка от удачного запуска ComThread.
program ComThread;
uses System.Win.ComObj, Winapi.ActiveX;
procedure Worker;
begin
  OleCheck(CoInitializeEx(nil, COINIT_APARTMENTTHREADED));
  try
    { create and use COM objects in this apartment }
  finally
    CoUninitialize;
  end;
end;
begin end.

// Определите реальную гарантию в MessageLoopWork.
program MessageLoopWork;
uses Winapi.Windows;
function WindowProc(Wnd: HWND; Msg: UINT; WParam: WPARAM; LParam: LPARAM): LRESULT; stdcall;
begin
  if Msg = WM_COMMAND then
  begin
    Sleep(8000);
    Result := 0;
    Exit;
  end;
  Result := DefWindowProc(Wnd, Msg, WParam, LParam);
end;
begin end.