samples/except/except.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        samples/except/except.cpp
   3 // Purpose:     shows how C++ exceptions can be used in wxWidgets
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     2003-09-17
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2003-2005 Vadim Zeitlin
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 // ============================================================================
  13 // declarations
  14 // ============================================================================
  15
  16 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 // For compilers that support precompilation, includes "wx/wx.h".
  21 #include "wx/wxprec.h"
  22
  23 #ifdef __BORLANDC__
  24     #pragma hdrstop
  25 #endif
  26
  27 #if !wxUSE_EXCEPTIONS
  28     #error "This sample only works with wxUSE_EXCEPTIONS == 1"
  29 #endif // !wxUSE_EXCEPTIONS
  30
  31 // for all others, include the necessary headers (this file is usually all you
  32 // need because it includes almost all "standard" wxWidgets headers)
  33 #ifndef WX_PRECOMP
  34     #include "wx/log.h"
  35
  36     #include "wx/app.h"
  37     #include "wx/frame.h"
  38     #include "wx/dialog.h"
  39     #include "wx/menu.h"
  40
  41     #include "wx/button.h"
  42     #include "wx/sizer.h"
  43
  44     #include "wx/utils.h"
  45     #include "wx/msgdlg.h"
  46     #include "wx/icon.h"
  47 #endif
  48
  49 // ----------------------------------------------------------------------------
  50 // resources
  51 // ----------------------------------------------------------------------------
  52
  53 // the application icon (under Windows and OS/2 it is in resources)
  54 #if defined(__WXGTK__) || defined(__WXMOTIF__) || defined(__WXMAC__) || defined(__WXMGL__) || defined(__WXX11__)
  55     #include "../sample.xpm"
  56 #endif
  57
  58 // ----------------------------------------------------------------------------
  59 // private functions
  60 // ----------------------------------------------------------------------------
  61
  62 static void DoCrash()
  63 {
  64     char *p = 0;
  65     strcpy(p, "Let's crash");
  66 }
  67
  68 // ----------------------------------------------------------------------------
  69 // private classes
  70 // ----------------------------------------------------------------------------
  71
  72 // Define a new application type, each program should derive a class from wxApp
  73 class MyApp : public wxApp
  74 {
  75 public:
  76     // override base class virtuals
  77     // ----------------------------
  78
  79     // program startup
  80     virtual bool OnInit();
  81
  82     // 2nd-level exception handling: we get all the exceptions occurring in any
  83     // event handler here
  84     virtual bool OnExceptionInMainLoop();
  85
  86     // 3rd, and final, level exception handling: whenever an unhandled
  87     // exception is caught, this function is called
  88     virtual void OnUnhandledException();
  89
  90     // and now for something different: this function is called in case of a
  91     // crash (e.g. dereferencing null pointer, division by 0, ...)
  92     virtual void OnFatalException();
  93
  94     // you can override this function to do something different (e.g. log the
  95     // assert to file) whenever an assertion fails
  96     virtual void OnAssertFailure(const wxChar *file,
  97                                  int line,
  98                                  const wxChar *func,
  99                                  const wxChar *cond,
 100                                  const wxChar *msg);
 101 };
 102
 103 // Define a new frame type: this is going to be our main frame
 104 class MyFrame : public wxFrame
 105 {
 106 public:
 107     // ctor(s)
 108     MyFrame();
 109
 110     // event handlers (these functions should _not_ be virtual)
 111     void OnQuit(wxCommandEvent& event);
 112     void OnAbout(wxCommandEvent& event);
 113     void OnDialog(wxCommandEvent& event);
 114
 115     void OnThrowInt(wxCommandEvent& event);
 116     void OnThrowString(wxCommandEvent& event);
 117     void OnThrowObject(wxCommandEvent& event);
 118     void OnThrowUnhandled(wxCommandEvent& event);
 119
 120     void OnCrash(wxCommandEvent& event);
 121 #if wxUSE_ON_FATAL_EXCEPTION
 122     void OnHandleCrash(wxCommandEvent& event);
 123 #endif
 124
 125 protected:
 126
 127     // 1st-level exception handling: we overload ProcessEvent() to be able to
 128     // catch exceptions which occur in MyFrame methods here
 129     virtual bool ProcessEvent(wxEvent& event);
 130
 131 #ifdef __WXDEBUG__
 132     // show how an assert failure message box looks like
 133     void OnShowAssert(wxCommandEvent& event);
 134 #endif // __WXDEBUG__
 135
 136 private:
 137     // any class wishing to process wxWidgets events must use this macro
 138     DECLARE_EVENT_TABLE()
 139 };
 140
 141 // A simple dialog which has only some buttons to throw exceptions
 142 class MyDialog : public wxDialog
 143 {
 144 public:
 145     MyDialog(wxFrame *parent);
 146
 147     // event handlers
 148     void OnThrowInt(wxCommandEvent& event);
 149     void OnThrowObject(wxCommandEvent& event);
 150     void OnCrash(wxCommandEvent& event);
 151
 152 private:
 153     DECLARE_EVENT_TABLE()
 154 };
 155
 156 // A trivial exception class
 157 class MyException
 158 {
 159 public:
 160     MyException(const wxString& msg) : m_msg(msg) { }
 161
 162     const wxChar *what() const { return m_msg.c_str(); }
 163
 164 private:
 165     wxString m_msg;
 166 };
 167
 168 // Another exception class which just has to be different from anything else
 169 class UnhandledException
 170 {
 171 };
 172
 173 // ----------------------------------------------------------------------------
 174 // constants
 175 // ----------------------------------------------------------------------------
 176
 177 // IDs for the controls and the menu commands
 178 enum
 179 {
 180     // control ids and menu items
 181     Except_ThrowInt = wxID_HIGHEST,
 182     Except_ThrowString,
 183     Except_ThrowObject,
 184     Except_ThrowUnhandled,
 185     Except_Crash,
 186 #if wxUSE_ON_FATAL_EXCEPTION
 187     Except_HandleCrash,
 188 #endif // wxUSE_ON_FATAL_EXCEPTION
 189 #ifdef __WXDEBUG__
 190     Except_ShowAssert,
 191 #endif // __WXDEBUG__
 192     Except_Dialog,
 193
 194     Except_Quit = wxID_EXIT,
 195     Except_About = wxID_ABOUT
 196 };
 197
 198 // ----------------------------------------------------------------------------
 199 // event tables and other macros for wxWidgets
 200 // ----------------------------------------------------------------------------
 201
 202 // the event tables connect the wxWidgets events with the functions (event
 203 // handlers) which process them. It can be also done at run-time, but for the
 204 // simple menu events like this the static method is much simpler.
 205 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 206     EVT_MENU(Except_Quit,  MyFrame::OnQuit)
 207     EVT_MENU(Except_About, MyFrame::OnAbout)
 208     EVT_MENU(Except_Dialog, MyFrame::OnDialog)
 209     EVT_MENU(Except_ThrowInt, MyFrame::OnThrowInt)
 210     EVT_MENU(Except_ThrowString, MyFrame::OnThrowString)
 211     EVT_MENU(Except_ThrowObject, MyFrame::OnThrowObject)
 212     EVT_MENU(Except_ThrowUnhandled, MyFrame::OnThrowUnhandled)
 213     EVT_MENU(Except_Crash, MyFrame::OnCrash)
 214 #if wxUSE_ON_FATAL_EXCEPTION
 215     EVT_MENU(Except_HandleCrash, MyFrame::OnHandleCrash)
 216 #endif // wxUSE_ON_FATAL_EXCEPTION
 217 #ifdef __WXDEBUG__
 218     EVT_MENU(Except_ShowAssert, MyFrame::OnShowAssert)
 219 #endif // __WXDEBUG__
 220 END_EVENT_TABLE()
 221
 222 BEGIN_EVENT_TABLE(MyDialog, wxDialog)
 223     EVT_BUTTON(Except_ThrowInt, MyDialog::OnThrowInt)
 224     EVT_BUTTON(Except_ThrowObject, MyDialog::OnThrowObject)
 225     EVT_BUTTON(Except_Crash, MyDialog::OnCrash)
 226 END_EVENT_TABLE()
 227
 228 // Create a new application object: this macro will allow wxWidgets to create
 229 // the application object during program execution (it's better than using a
 230 // static object for many reasons) and also implements the accessor function
 231 // wxGetApp() which will return the reference of the right type (i.e. MyApp and
 232 // not wxApp)
 233 IMPLEMENT_APP(MyApp)
 234
 235 // ============================================================================
 236 // MyApp implementation
 237 // ============================================================================
 238
 239 // 'Main program' equivalent: the program execution "starts" here
 240 bool MyApp::OnInit()
 241 {
 242     if ( !wxApp::OnInit() )
 243         return false;
 244
 245     // create the main application window
 246     MyFrame *frame = new MyFrame();
 247
 248     // and show it (the frames, unlike simple controls, are not shown when
 249     // created initially)
 250     frame->Show(true);
 251
 252     // success: wxApp::OnRun() will be called which will enter the main message
 253     // loop and the application will run. If we returned false here, the
 254     // application would exit immediately.
 255     return true;
 256 }
 257
 258 bool MyApp::OnExceptionInMainLoop()
 259 {
 260     try
 261     {
 262         throw;
 263     }
 264     catch ( int i )
 265     {
 266         wxLogWarning(wxT("Caught an int %d in MyApp."), i);
 267     }
 268     catch ( MyException& e )
 269     {
 270         wxLogWarning(wxT("Caught MyException(%s) in MyApp."), e.what());
 271     }
 272     catch ( ... )
 273     {
 274         throw;
 275     }
 276
 277     return true;
 278 }
 279
 280 void MyApp::OnUnhandledException()
 281 {
 282     // this shows how we may let some exception propagate uncaught
 283     try
 284     {
 285         throw;
 286     }
 287     catch ( UnhandledException& )
 288     {
 289         throw;
 290     }
 291     catch ( ... )
 292     {
 293         wxMessageBox(wxT("Unhandled exception caught, program will terminate."),
 294                      wxT("wxExcept Sample"), wxOK | wxICON_ERROR);
 295     }
 296 }
 297
 298 void MyApp::OnFatalException()
 299 {
 300     wxMessageBox(wxT("Program has crashed and will terminate."),
 301                  wxT("wxExcept Sample"), wxOK | wxICON_ERROR);
 302 }
 303
 304 void MyApp::OnAssertFailure(const wxChar *file,
 305                             int line,
 306                             const wxChar *func,
 307                             const wxChar *cond,
 308                             const wxChar *msg)
 309 {
 310     if ( wxMessageBox
 311          (
 312             wxString::Format("An assert failed in %s().", func) +
 313             "\n"
 314             "Do you want to call the default assert handler?",
 315             "wxExcept Sample",
 316             wxYES_NO | wxICON_QUESTION
 317          ) == wxYES )
 318     {
 319         wxApp::OnAssertFailure(file, line, func, cond, msg);
 320     }
 321 }
 322
 323 // ============================================================================
 324 // MyFrame implementation
 325 // ============================================================================
 326
 327 // frame constructor
 328 MyFrame::MyFrame()
 329        : wxFrame(NULL, wxID_ANY, wxT("Except wxWidgets App"),
 330                  wxPoint(50, 50), wxSize(450, 340))
 331 {
 332     // set the frame icon
 333     SetIcon(wxICON(sample));
 334
 335 #if wxUSE_MENUS
 336     // create a menu bar
 337     wxMenu *menuFile = new wxMenu;
 338     menuFile->Append(Except_Dialog, wxT("Show &dialog\tCtrl-D"));
 339     menuFile->AppendSeparator();
 340     menuFile->Append(Except_ThrowInt, wxT("Throw an &int\tCtrl-I"));
 341     menuFile->Append(Except_ThrowString, wxT("Throw a &string\tCtrl-S"));
 342     menuFile->Append(Except_ThrowObject, wxT("Throw an &object\tCtrl-O"));
 343     menuFile->Append(Except_ThrowUnhandled,
 344                         wxT("Throw &unhandled exception\tCtrl-U"));
 345     menuFile->Append(Except_Crash, wxT("&Crash\tCtrl-C"));
 346     menuFile->AppendSeparator();
 347 #if wxUSE_ON_FATAL_EXCEPTION
 348     menuFile->AppendCheckItem(Except_HandleCrash, wxT("&Handle crashes\tCtrl-H"));
 349     menuFile->AppendSeparator();
 350 #endif // wxUSE_ON_FATAL_EXCEPTION
 351 #ifdef __WXDEBUG__
 352     menuFile->Append(Except_ShowAssert, wxT("Provoke &assert failure\tCtrl-A"));
 353     menuFile->AppendSeparator();
 354 #endif // __WXDEBUG__
 355     menuFile->Append(Except_Quit, wxT("E&xit\tCtrl-Q"), wxT("Quit this program"));
 356
 357     wxMenu *helpMenu = new wxMenu;
 358     helpMenu->Append(Except_About, wxT("&About...\tF1"), wxT("Show about dialog"));
 359
 360     // now append the freshly created menu to the menu bar...
 361     wxMenuBar *menuBar = new wxMenuBar();
 362     menuBar->Append(menuFile, wxT("&File"));
 363     menuBar->Append(helpMenu, wxT("&Help"));
 364
 365     // ... and attach this menu bar to the frame
 366     SetMenuBar(menuBar);
 367 #endif // wxUSE_MENUS
 368
 369 #if wxUSE_STATUSBAR && !defined(__WXWINCE__)
 370     // create a status bar just for fun (by default with 1 pane only)
 371     CreateStatusBar(2);
 372     SetStatusText(wxT("Welcome to wxWidgets!"));
 373 #endif // wxUSE_STATUSBAR
 374 }
 375
 376 bool MyFrame::ProcessEvent(wxEvent& event)
 377 {
 378     try
 379     {
 380         return wxFrame::ProcessEvent(event);
 381     }
 382     catch ( const wxChar *msg )
 383     {
 384         wxLogMessage(wxT("Caught a string \"%s\" in MyFrame"), msg);
 385
 386         return true;
 387     }
 388 }
 389
 390 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 391 {
 392     // true is to force the frame to close
 393     Close(true);
 394 }
 395
 396 void MyFrame::OnDialog(wxCommandEvent& WXUNUSED(event))
 397 {
 398     try
 399     {
 400         MyDialog dlg(this);
 401
 402         dlg.ShowModal();
 403     }
 404     catch ( ... )
 405     {
 406         wxLogWarning(wxT("An exception in MyDialog"));
 407
 408         Destroy();
 409         throw;
 410     }
 411 }
 412
 413 void MyFrame::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 414 {
 415     throw -17;
 416 }
 417
 418 void MyFrame::OnThrowString(wxCommandEvent& WXUNUSED(event))
 419 {
 420     throw wxT("string thrown from MyFrame");
 421 }
 422
 423 void MyFrame::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 424 {
 425     throw MyException(wxT("Exception thrown from MyFrame"));
 426 }
 427
 428 void MyFrame::OnThrowUnhandled(wxCommandEvent& WXUNUSED(event))
 429 {
 430     throw UnhandledException();
 431 }
 432
 433 void MyFrame::OnCrash(wxCommandEvent& WXUNUSED(event))
 434 {
 435     DoCrash();
 436 }
 437
 438 #if wxUSE_ON_FATAL_EXCEPTION
 439
 440 void MyFrame::OnHandleCrash(wxCommandEvent& event)
 441 {
 442     wxHandleFatalExceptions(event.IsChecked());
 443 }
 444
 445 #endif // wxUSE_ON_FATAL_EXCEPTION
 446
 447 #ifdef __WXDEBUG__
 448
 449 void MyFrame::OnShowAssert(wxCommandEvent& WXUNUSED(event))
 450 {
 451     // provoke an assert from wxArrayString
 452     wxArrayString arr;
 453     arr[0];
 454 }
 455
 456 #endif // __WXDEBUG__
 457
 458 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 459 {
 460     wxString msg;
 461     msg.Printf( wxT("This is the About dialog of the except sample.\n")
 462                 wxT("Welcome to %s"), wxVERSION_STRING);
 463
 464     wxMessageBox(msg, wxT("About Except"), wxOK | wxICON_INFORMATION, this);
 465 }
 466
 467 // ============================================================================
 468 // MyDialog implementation
 469 // ============================================================================
 470
 471 MyDialog::MyDialog(wxFrame *parent)
 472         : wxDialog(parent, wxID_ANY, wxString(wxT("Throw exception dialog")))
 473 {
 474     wxSizer *sizerTop = new wxBoxSizer(wxVERTICAL);
 475
 476     sizerTop->Add(new wxButton(this, Except_ThrowInt, wxT("Throw &int")),
 477                   0, wxCENTRE | wxALL, 5);
 478     sizerTop->Add(new wxButton(this, Except_ThrowObject, wxT("Throw &object")),
 479                   0, wxCENTRE | wxALL, 5);
 480     sizerTop->Add(new wxButton(this, Except_Crash, wxT("&Crash")),
 481                   0, wxCENTRE | wxALL, 5);
 482     sizerTop->Add(new wxButton(this, wxID_CANCEL, wxT("&Cancel")),
 483                   0, wxCENTRE | wxALL, 5);
 484
 485     SetSizerAndFit(sizerTop);
 486 }
 487
 488 void MyDialog::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 489 {
 490     throw 17;
 491 }
 492
 493 void MyDialog::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 494 {
 495     throw MyException(wxT("Exception thrown from MyDialog"));
 496 }
 497
 498 void MyDialog::OnCrash(wxCommandEvent& WXUNUSED(event))
 499 {
 500     DoCrash();
 501 }
 502