interface/process.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        process.h
   3 // Purpose:     documentation for wxProcess class
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxProcess
  11     @wxheader{process.h}
  12
  13     The objects of this class are used in conjunction with the
  14     wxExecute function. When a wxProcess object is passed to
  15     wxExecute(), its wxProcess::OnTerminate virtual method
  16     is called when the process terminates. This allows the program to be
  17     (asynchronously) notified about the process termination and also retrieve its
  18     exit status which is unavailable from wxExecute() in the case of
  19     asynchronous execution.
  20
  21     Please note that if the process termination notification is processed by the
  22     parent, it is responsible for deleting the wxProcess object which sent it.
  23     However, if it is not processed, the object will delete itself and so the
  24     library users should only delete those objects whose notifications have been
  25     processed (and call wxProcess::Detach for others).
  26
  27     wxProcess also supports IO redirection of the child process. For this, you have
  28     to call its wxProcess::Redirect method before passing it to
  29     wxExecute. If the child process was launched successfully,
  30     wxProcess::GetInputStream,
  31     wxProcess::GetOutputStream and
  32     wxProcess::GetErrorStream can then be used to retrieve
  33     the streams corresponding to the child process standard output, input and
  34     error output respectively.
  35
  36     @b wxPerl note: In wxPerl this class has an additional @c Destroy method,
  37     for explicit destruction.
  38
  39     @library{wxbase}
  40     @category{appmanagement}
  41
  42     @seealso
  43     wxExecute, @ref overview_sampleexec "exec sample"
  44 */
  45 class wxProcess : public wxEvtHandler
  46 {
  47 public:
  48     //@{
  49     /**
  50         Constructs a process object. @a id is only used in the case you want to
  51         use wxWidgets events. It identifies this object, or another window that will
  52         receive the event.
  53         If the @a parent parameter is different from @NULL, it will receive
  54         a wxEVT_END_PROCESS notification event (you should insert EVT_END_PROCESS
  55         macro in the event table of the parent to handle it) with the given @e id.
  56         The second constructor creates an object without any associated parent (and
  57         hence no id neither) but allows to specify the @a flags which can have the
  58         value of @c wxPROCESS_DEFAULT or @c wxPROCESS_REDIRECT. Specifying the
  59         former value has no particular effect while using the latter one is equivalent
  60         to calling Redirect().
  61
  62         @param parent
  63             The event handler parent.
  64         @param id
  65             id of an event.
  66         @param flags
  67             either wxPROCESS_DEFAULT or wxPROCESS_REDIRECT
  68     */
  69     wxProcess(wxEvtHandler* parent = NULL, int id = -1);
  70     wxProcess(int flags);
  71     //@}
  72
  73     /**
  74         Destroys the wxProcess object.
  75     */
  76     ~wxProcess();
  77
  78     /**
  79         Closes the output stream (the one connected to the stdin of the child
  80         process). This function can be used to indicate to the child process that
  81         there is no more data to be read - usually, a filter program will only
  82         terminate when the input stream is closed.
  83     */
  84     void CloseOutput();
  85
  86     /**
  87         Normally, a wxProcess object is deleted by its parent when it receives the
  88         notification about the process termination. However, it might happen that the
  89         parent object is destroyed before the external process is terminated (e.g. a
  90         window from which this external process was launched is closed by the user)
  91         and in this case it @b should not delete the wxProcess object, but
  92         @b should call Detach() instead. After the wxProcess object is detached
  93         from its parent, no notification events will be sent to the parent and the
  94         object will delete itself upon reception of the process termination
  95         notification.
  96     */
  97     void Detach();
  98
  99     /**
 100         Returns @true if the given process exists in the system.
 101
 102         @see Kill(), @ref overview_sampleexec "Exec sample"
 103     */
 104     static bool Exists(int pid);
 105
 106     /**
 107         Returns an input stream which corresponds to the standard error output (stderr)
 108         of the child process.
 109     */
 110     wxInputStream* GetErrorStream() const;
 111
 112     /**
 113         It returns an input stream corresponding to the standard output stream of the
 114         subprocess. If it is @NULL, you have not turned on the redirection.
 115         See Redirect().
 116     */
 117     wxInputStream* GetInputStream() const;
 118
 119     /**
 120         It returns an output stream correspoding to the input stream of the subprocess.
 121         If it is @NULL, you have not turned on the redirection.
 122         See Redirect().
 123     */
 124     wxOutputStream* GetOutputStream() const;
 125
 126     /**
 127         Returns the process ID of the process launched by Open().
 128     */
 129     long GetPid() const;
 130
 131     /**
 132         Returns @true if there is data to be read on the child process standard
 133         error stream.
 134
 135         @see IsInputAvailable()
 136     */
 137     bool IsErrorAvailable() const;
 138
 139     /**
 140         Returns @true if there is data to be read on the child process standard
 141         output stream. This allows to write simple (and extremely inefficient)
 142         polling-based code waiting for a better mechanism in future wxWidgets versions.
 143         See the @ref overview_sampleexec "exec sample" for an example of using this
 144         function.
 145
 146         @see IsInputOpened()
 147     */
 148     bool IsInputAvailable() const;
 149
 150     /**
 151         Returns @true if the child process standard output stream is opened.
 152     */
 153     bool IsInputOpened() const;
 154
 155     /**
 156         Send the specified signal to the given process. Possible signal values are:
 157
 158         @c wxSIGNONE, @c wxSIGKILL and @c wxSIGTERM have the same meaning
 159         under both Unix and Windows but all the other signals are equivalent to
 160         @c wxSIGTERM under Windows.
 161         The @a flags parameter can be wxKILL_NOCHILDREN (the default),
 162         or wxKILL_CHILDREN, in which case the child processes of this
 163         process will be killed too. Note that under Unix, for wxKILL_CHILDREN
 164         to work you should have created the process passing wxEXEC_MAKE_GROUP_LEADER.
 165         Returns the element of @c wxKillError enum:
 166
 167         @see Exists(), wxKill, @ref overview_sampleexec "Exec sample"
 168     */
 169     static wxKillError Kill(int pid, wxSignal signal = wxSIGNONE,
 170                             int flags = wxKILL_NOCHILDREN);
 171
 172     /**
 173         It is called when the process with the pid
 174
 175         @param pid finishes.
 176         It raises a wxWidgets event when it isn't overridden.
 177
 178         pid
 179             The pid of the process which has just terminated.
 180         @param status
 181             The exit code of the process.
 182     */
 183     void OnTerminate(int pid, int status);
 184
 185     /**
 186         This static method replaces the standard @c popen() function: it launches
 187         the process specified by the @a cmd parameter and returns the wxProcess
 188         object which can be used to retrieve the streams connected to the standard
 189         input, output and error output of the child process.
 190         If the process couldn't be launched, @NULL is returned. Note that in any
 191         case the returned pointer should @b not be deleted, rather the process
 192         object will be destroyed automatically when the child process terminates. This
 193         does mean that the child process should be told to quit before the main program
 194         exits to avoid memory leaks.
 195
 196         @param cmd
 197             The command to execute, including optional arguments.
 198         @param flags
 199             The flags to pass to wxExecute.
 200               NOTE: wxEXEC_SYNC should not be used.
 201
 202         @returns A pointer to new wxProcess object or @NULL on error.
 203
 204         @see wxExecute
 205     */
 206     static wxProcess* Open(const wxString& cmd,
 207                            int flags = wxEXEC_ASYNC);
 208
 209     /**
 210         Turns on redirection. wxExecute will try to open a couple of pipes
 211         to catch the subprocess stdio. The caught input stream is returned by
 212         GetOutputStream() as a non-seekable stream. The caught output stream is returned
 213         by GetInputStream() as a non-seekable stream.
 214     */
 215     void Redirect();
 216 };
 217
 218
 219 /**
 220     @class wxProcessEvent
 221     @wxheader{process.h}
 222
 223     A process event is sent when a process is terminated.
 224
 225     @library{wxbase}
 226     @category{events}
 227
 228     @seealso
 229     wxProcess, @ref overview_eventhandlingoverview
 230 */
 231 class wxProcessEvent : public wxEvent
 232 {
 233 public:
 234     /**
 235         Constructor. Takes a wxProcessObject or window id, a process id and an
 236         exit status.
 237     */
 238     wxProcessEvent(int id = 0, int pid = 0, int exitcode = 0);
 239
 240     /**
 241         Returns the exist status.
 242     */
 243     int GetExitCode();
 244
 245     /**
 246         Returns the process id.
 247     */
 248     int GetPid() const;
 249 };