interface/snglinst.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        snglinst.h
   3 // Purpose:     documentation for wxSingleInstanceChecker class
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxSingleInstanceChecker
  11     @wxheader{snglinst.h}
  12
  13     wxSingleInstanceChecker class allows to check that only a single instance of a
  14     program is running. To do it, you should create an object of this class. As
  15     long as this object is alive, calls to
  16     wxSingleInstanceChecker::IsAnotherRunning from
  17     other processes will return @true.
  18
  19     As the object should have the life span as big as possible, it makes sense to
  20     create it either as a global or in wxApp::OnInit. For
  21     example:
  22
  23     @code
  24     bool MyApp::OnInit()
  25     {
  26         const wxString name = wxString::Format("MyApp-%s", wxGetUserId().c_str());
  27         m_checker = new wxSingleInstanceChecker(name);
  28         if ( m_checker-IsAnotherRunning() )
  29         {
  30             wxLogError(_("Another program instance is already running, aborting."));
  31
  32             delete m_checker; // OnExit() won't be called if we return @false
  33             m_checker = @NULL;
  34
  35             return @false;
  36         }
  37
  38         ... more initializations ...
  39
  40         return @true;
  41     }
  42
  43     int MyApp::OnExit()
  44     {
  45         delete m_checker;
  46
  47         return 0;
  48     }
  49     @endcode
  50
  51     Note using wxGetUserId to construct the name: this
  52     allows different user to run the application concurrently which is usually the
  53     intended goal. If you don't use the user name in the wxSingleInstanceChecker
  54     name, only one user would be able to run the application at a time.
  55
  56     This class is implemented for Win32 and Unix platforms (supporting @c fcntl()
  57     system call, but almost all of modern Unix systems do) only.
  58
  59     @library{wxbase}
  60     @category{misc}
  61 */
  62 class wxSingleInstanceChecker
  63 {
  64 public:
  65     /**
  66         Like Create() but without
  67         error checking.
  68     */
  69     wxSingleInstanceChecker(const wxString& name,
  70                             const wxString& path = wxEmptyString);
  71
  72     /**
  73         Destructor frees the associated resources.
  74
  75         Note that it is not virtual, this class is not meant to be used polymorphically
  76     */
  77     ~wxSingleInstanceChecker();
  78
  79     /**
  80         Initialize the object if it had been created using the default constructor.
  81         Note that you can't call Create() more than once, so calling it if the
  82         @ref wxsingleinstancechecker() "non default ctor"
  83         had been used is an error.
  84
  85         @param name
  86         must be given and be as unique as possible. It is used as the
  87         mutex name under Win32 and the lock file name under Unix.
  88         GetAppName() and wxGetUserId()
  89         are commonly used to construct this parameter.
  90
  91         @param path
  92         is optional and is ignored under Win32 and used as the directory to
  93         create the lock file in under Unix (default is
  94         wxGetHomeDir())
  95
  96         @returns Returns @false if initialization failed, it doesn't mean that
  97                    another instance is running - use  IsAnotherRunning()
  98                    to check for it.
  99     */
 100     bool Create(const wxString& name,
 101                 const wxString& path = wxEmptyString);
 102
 103     /**
 104         Returns @true if another copy of this program is already running, @false
 105         otherwise.
 106     */
 107     bool IsAnotherRunning();
 108 };