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
  48     #include "wx/thread.h"
  49 #endif
  50
  51 // ----------------------------------------------------------------------------
  52 // resources
  53 // ----------------------------------------------------------------------------
  54
  55 // the application icon (under Windows and OS/2 it is in resources)
  56 #ifndef wxHAS_IMAGES_IN_RESOURCES
  57     #include "../sample.xpm"
  58 #endif
  59
  60 // ----------------------------------------------------------------------------
  61 // private functions
  62 // ----------------------------------------------------------------------------
  63
  64 static void DoCrash()
  65 {
  66     char *p = 0;
  67     strcpy(p, "Let's crash");
  68 }
  69
  70 // ----------------------------------------------------------------------------
  71 // private classes
  72 // ----------------------------------------------------------------------------
  73
  74 // Define a new application type, each program should derive a class from wxApp
  75 class MyApp : public wxApp
  76 {
  77 public:
  78     // override base class virtuals
  79     // ----------------------------
  80
  81     // program startup
  82     virtual bool OnInit();
  83
  84     // 2nd-level exception handling: we get all the exceptions occurring in any
  85     // event handler here
  86     virtual bool OnExceptionInMainLoop();
  87
  88     // 3rd, and final, level exception handling: whenever an unhandled
  89     // exception is caught, this function is called
  90     virtual void OnUnhandledException();
  91
  92     // and now for something different: this function is called in case of a
  93     // crash (e.g. dereferencing null pointer, division by 0, ...)
  94     virtual void OnFatalException();
  95
  96     // you can override this function to do something different (e.g. log the
  97     // assert to file) whenever an assertion fails
  98     virtual void OnAssertFailure(const wxChar *file,
  99                                  int line,
 100                                  const wxChar *func,
 101                                  const wxChar *cond,
 102                                  const wxChar *msg);
 103 };
 104
 105 // Define a new frame type: this is going to be our main frame
 106 class MyFrame : public wxFrame
 107 {
 108 public:
 109     // ctor(s)
 110     MyFrame();
 111
 112     // event handlers (these functions should _not_ be virtual)
 113     void OnQuit(wxCommandEvent& event);
 114     void OnAbout(wxCommandEvent& event);
 115     void OnDialog(wxCommandEvent& event);
 116
 117     void OnThrowInt(wxCommandEvent& event);
 118     void OnThrowString(wxCommandEvent& event);
 119     void OnThrowObject(wxCommandEvent& event);
 120     void OnThrowUnhandled(wxCommandEvent& event);
 121
 122     void OnCrash(wxCommandEvent& event);
 123     void OnTrap(wxCommandEvent& event);
 124 #if wxUSE_ON_FATAL_EXCEPTION
 125     void OnHandleCrash(wxCommandEvent& event);
 126 #endif
 127
 128 protected:
 129
 130     // 1st-level exception handling: we overload ProcessEvent() to be able to
 131     // catch exceptions which occur in MyFrame methods here
 132     virtual bool ProcessEvent(wxEvent& event);
 133
 134     // provoke assert in main or worker thread
 135     //
 136     // this is used to show how an assert failure message box looks like
 137     void OnShowAssert(wxCommandEvent& event);
 138 #if wxUSE_THREADS
 139     void OnShowAssertInThread(wxCommandEvent& event);
 140 #endif // wxUSE_THREADS
 141
 142 private:
 143     // any class wishing to process wxWidgets events must use this macro
 144     DECLARE_EVENT_TABLE()
 145 };
 146
 147 // A simple dialog which has only some buttons to throw exceptions
 148 class MyDialog : public wxDialog
 149 {
 150 public:
 151     MyDialog(wxFrame *parent);
 152
 153     // event handlers
 154     void OnThrowInt(wxCommandEvent& event);
 155     void OnThrowObject(wxCommandEvent& event);
 156     void OnCrash(wxCommandEvent& event);
 157
 158 private:
 159     DECLARE_EVENT_TABLE()
 160 };
 161
 162 // A trivial exception class
 163 class MyException
 164 {
 165 public:
 166     MyException(const wxString& msg) : m_msg(msg) { }
 167
 168     const wxChar *what() const { return m_msg.c_str(); }
 169
 170 private:
 171     wxString m_msg;
 172 };
 173
 174 // Another exception class which just has to be different from anything else
 175 class UnhandledException
 176 {
 177 };
 178
 179 // ----------------------------------------------------------------------------
 180 // constants
 181 // ----------------------------------------------------------------------------
 182
 183 // IDs for the controls and the menu commands
 184 enum
 185 {
 186     // control ids and menu items
 187     Except_ThrowInt = wxID_HIGHEST,
 188     Except_ThrowString,
 189     Except_ThrowObject,
 190     Except_ThrowUnhandled,
 191     Except_Crash,
 192     Except_Trap,
 193 #if wxUSE_ON_FATAL_EXCEPTION
 194     Except_HandleCrash,
 195 #endif // wxUSE_ON_FATAL_EXCEPTION
 196     Except_ShowAssert,
 197 #if wxUSE_THREADS
 198     Except_ShowAssertInThread,
 199 #endif // wxUSE_THREADS
 200     Except_Dialog,
 201
 202     Except_Quit = wxID_EXIT,
 203     Except_About = wxID_ABOUT
 204 };
 205
 206 // ----------------------------------------------------------------------------
 207 // event tables and other macros for wxWidgets
 208 // ----------------------------------------------------------------------------
 209
 210 // the event tables connect the wxWidgets events with the functions (event
 211 // handlers) which process them. It can be also done at run-time, but for the
 212 // simple menu events like this the static method is much simpler.
 213 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 214     EVT_MENU(Except_Quit,  MyFrame::OnQuit)
 215     EVT_MENU(Except_About, MyFrame::OnAbout)
 216     EVT_MENU(Except_Dialog, MyFrame::OnDialog)
 217     EVT_MENU(Except_ThrowInt, MyFrame::OnThrowInt)
 218     EVT_MENU(Except_ThrowString, MyFrame::OnThrowString)
 219     EVT_MENU(Except_ThrowObject, MyFrame::OnThrowObject)
 220     EVT_MENU(Except_ThrowUnhandled, MyFrame::OnThrowUnhandled)
 221     EVT_MENU(Except_Crash, MyFrame::OnCrash)
 222     EVT_MENU(Except_Trap, MyFrame::OnTrap)
 223 #if wxUSE_ON_FATAL_EXCEPTION
 224     EVT_MENU(Except_HandleCrash, MyFrame::OnHandleCrash)
 225 #endif // wxUSE_ON_FATAL_EXCEPTION
 226     EVT_MENU(Except_ShowAssert, MyFrame::OnShowAssert)
 227 #if wxUSE_THREADS
 228     EVT_MENU(Except_ShowAssertInThread, MyFrame::OnShowAssertInThread)
 229 #endif // wxUSE_THREADS
 230 END_EVENT_TABLE()
 231
 232 BEGIN_EVENT_TABLE(MyDialog, wxDialog)
 233     EVT_BUTTON(Except_ThrowInt, MyDialog::OnThrowInt)
 234     EVT_BUTTON(Except_ThrowObject, MyDialog::OnThrowObject)
 235     EVT_BUTTON(Except_Crash, MyDialog::OnCrash)
 236 END_EVENT_TABLE()
 237
 238 // Create a new application object: this macro will allow wxWidgets to create
 239 // the application object during program execution (it's better than using a
 240 // static object for many reasons) and also implements the accessor function
 241 // wxGetApp() which will return the reference of the right type (i.e. MyApp and
 242 // not wxApp)
 243 IMPLEMENT_APP(MyApp)
 244
 245 // ============================================================================
 246 // MyApp implementation
 247 // ============================================================================
 248
 249 // 'Main program' equivalent: the program execution "starts" here
 250 bool MyApp::OnInit()
 251 {
 252     if ( !wxApp::OnInit() )
 253         return false;
 254
 255     // create the main application window
 256     MyFrame *frame = new MyFrame();
 257
 258     // and show it (the frames, unlike simple controls, are not shown when
 259     // created initially)
 260     frame->Show(true);
 261
 262     // success: wxApp::OnRun() will be called which will enter the main message
 263     // loop and the application will run. If we returned false here, the
 264     // application would exit immediately.
 265     return true;
 266 }
 267
 268 bool MyApp::OnExceptionInMainLoop()
 269 {
 270     try
 271     {
 272         throw;
 273     }
 274     catch ( int i )
 275     {
 276         wxLogWarning(wxT("Caught an int %d in MyApp."), i);
 277     }
 278     catch ( MyException& e )
 279     {
 280         wxLogWarning(wxT("Caught MyException(%s) in MyApp."), e.what());
 281     }
 282     catch ( ... )
 283     {
 284         throw;
 285     }
 286
 287     return true;
 288 }
 289
 290 void MyApp::OnUnhandledException()
 291 {
 292     // this shows how we may let some exception propagate uncaught
 293     try
 294     {
 295         throw;
 296     }
 297     catch ( UnhandledException& )
 298     {
 299         throw;
 300     }
 301     catch ( ... )
 302     {
 303         wxMessageBox(wxT("Unhandled exception caught, program will terminate."),
 304                      wxT("wxExcept Sample"), wxOK | wxICON_ERROR);
 305     }
 306 }
 307
 308 void MyApp::OnFatalException()
 309 {
 310     wxMessageBox(wxT("Program has crashed and will terminate."),
 311                  wxT("wxExcept Sample"), wxOK | wxICON_ERROR);
 312 }
 313
 314 void MyApp::OnAssertFailure(const wxChar *file,
 315                             int line,
 316                             const wxChar *func,
 317                             const wxChar *cond,
 318                             const wxChar *msg)
 319 {
 320     // take care to not show the message box from a worker thread, this doesn't
 321     // work as it doesn't have any event loop
 322     if ( !wxIsMainThread() ||
 323             wxMessageBox
 324             (
 325                 wxString::Format("An assert failed in %s().", func) +
 326                 "\n"
 327                 "Do you want to call the default assert handler?",
 328                 "wxExcept Sample",
 329                 wxYES_NO | wxICON_QUESTION
 330             ) == wxYES )
 331     {
 332         wxApp::OnAssertFailure(file, line, func, cond, msg);
 333     }
 334 }
 335
 336 // ============================================================================
 337 // MyFrame implementation
 338 // ============================================================================
 339
 340 // frame constructor
 341 MyFrame::MyFrame()
 342        : wxFrame(NULL, wxID_ANY, wxT("Except wxWidgets App"),
 343                  wxPoint(50, 50), wxSize(450, 340))
 344 {
 345     // set the frame icon
 346     SetIcon(wxICON(sample));
 347
 348 #if wxUSE_MENUS
 349     // create a menu bar
 350     wxMenu *menuFile = new wxMenu;
 351     menuFile->Append(Except_Dialog, wxT("Show &dialog\tCtrl-D"));
 352     menuFile->AppendSeparator();
 353     menuFile->Append(Except_ThrowInt, wxT("Throw an &int\tCtrl-I"));
 354     menuFile->Append(Except_ThrowString, wxT("Throw a &string\tCtrl-S"));
 355     menuFile->Append(Except_ThrowObject, wxT("Throw an &object\tCtrl-O"));
 356     menuFile->Append(Except_ThrowUnhandled,
 357                         wxT("Throw &unhandled exception\tCtrl-U"));
 358     menuFile->Append(Except_Crash, wxT("&Crash\tCtrl-C"));
 359     menuFile->Append(Except_Trap, "&Trap\tCtrl-T",
 360                      "Break into the debugger (if one is running)");
 361     menuFile->AppendSeparator();
 362 #if wxUSE_ON_FATAL_EXCEPTION
 363     menuFile->AppendCheckItem(Except_HandleCrash, wxT("&Handle crashes\tCtrl-H"));
 364     menuFile->AppendSeparator();
 365 #endif // wxUSE_ON_FATAL_EXCEPTION
 366     menuFile->Append(Except_ShowAssert, wxT("Provoke &assert failure\tCtrl-A"));
 367 #if wxUSE_THREADS
 368     menuFile->Append(Except_ShowAssertInThread,
 369                      wxT("Assert failure in &thread\tShift-Ctrl-A"));
 370 #endif // wxUSE_THREADS
 371     menuFile->AppendSeparator();
 372     menuFile->Append(Except_Quit, wxT("E&xit\tCtrl-Q"), wxT("Quit this program"));
 373
 374     wxMenu *helpMenu = new wxMenu;
 375     helpMenu->Append(Except_About, wxT("&About\tF1"), wxT("Show about dialog"));
 376
 377     // now append the freshly created menu to the menu bar...
 378     wxMenuBar *menuBar = new wxMenuBar();
 379     menuBar->Append(menuFile, wxT("&File"));
 380     menuBar->Append(helpMenu, wxT("&Help"));
 381
 382     // ... and attach this menu bar to the frame
 383     SetMenuBar(menuBar);
 384 #endif // wxUSE_MENUS
 385
 386 #if wxUSE_STATUSBAR && !defined(__WXWINCE__)
 387     // create a status bar just for fun (by default with 1 pane only)
 388     CreateStatusBar(2);
 389     SetStatusText(wxT("Welcome to wxWidgets!"));
 390 #endif // wxUSE_STATUSBAR
 391 }
 392
 393 bool MyFrame::ProcessEvent(wxEvent& event)
 394 {
 395     try
 396     {
 397         return wxFrame::ProcessEvent(event);
 398     }
 399     catch ( const wxChar *msg )
 400     {
 401         wxLogMessage(wxT("Caught a string \"%s\" in MyFrame"), msg);
 402
 403         return true;
 404     }
 405 }
 406
 407 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 408 {
 409     // true is to force the frame to close
 410     Close(true);
 411 }
 412
 413 void MyFrame::OnDialog(wxCommandEvent& WXUNUSED(event))
 414 {
 415     try
 416     {
 417         MyDialog dlg(this);
 418
 419         dlg.ShowModal();
 420     }
 421     catch ( ... )
 422     {
 423         wxLogWarning(wxT("An exception in MyDialog"));
 424
 425         Destroy();
 426         throw;
 427     }
 428 }
 429
 430 void MyFrame::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 431 {
 432     throw -17;
 433 }
 434
 435 void MyFrame::OnThrowString(wxCommandEvent& WXUNUSED(event))
 436 {
 437     throw wxT("string thrown from MyFrame");
 438 }
 439
 440 void MyFrame::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 441 {
 442     throw MyException(wxT("Exception thrown from MyFrame"));
 443 }
 444
 445 void MyFrame::OnThrowUnhandled(wxCommandEvent& WXUNUSED(event))
 446 {
 447     throw UnhandledException();
 448 }
 449
 450 void MyFrame::OnCrash(wxCommandEvent& WXUNUSED(event))
 451 {
 452     DoCrash();
 453 }
 454
 455 void MyFrame::OnTrap(wxCommandEvent& WXUNUSED(event))
 456 {
 457     wxTrap();
 458 }
 459
 460 #if wxUSE_ON_FATAL_EXCEPTION
 461
 462 void MyFrame::OnHandleCrash(wxCommandEvent& event)
 463 {
 464     wxHandleFatalExceptions(event.IsChecked());
 465 }
 466
 467 #endif // wxUSE_ON_FATAL_EXCEPTION
 468
 469 void MyFrame::OnShowAssert(wxCommandEvent& WXUNUSED(event))
 470 {
 471     // provoke an assert from wxArrayString
 472     wxArrayString arr;
 473     arr[0];
 474 }
 475
 476 #if wxUSE_THREADS
 477
 478 void MyFrame::OnShowAssertInThread(wxCommandEvent& WXUNUSED(event))
 479 {
 480     class AssertThread : public wxThread
 481     {
 482     public:
 483         AssertThread()
 484             : wxThread(wxTHREAD_JOINABLE)
 485         {
 486         }
 487
 488     protected:
 489         virtual void *Entry()
 490         {
 491             wxFAIL_MSG("Test assert in another thread.");
 492
 493             return 0;
 494         }
 495     };
 496
 497     AssertThread thread;
 498     thread.Create();
 499     thread.Run();
 500     thread.Wait();
 501 }
 502
 503 #endif // wxUSE_THREADS
 504
 505 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 506 {
 507     wxString msg;
 508     msg.Printf( wxT("This is the About dialog of the except sample.\n")
 509                 wxT("Welcome to %s"), wxVERSION_STRING);
 510
 511     wxMessageBox(msg, wxT("About Except"), wxOK | wxICON_INFORMATION, this);
 512 }
 513
 514 // ============================================================================
 515 // MyDialog implementation
 516 // ============================================================================
 517
 518 MyDialog::MyDialog(wxFrame *parent)
 519         : wxDialog(parent, wxID_ANY, wxString(wxT("Throw exception dialog")))
 520 {
 521     wxSizer *sizerTop = new wxBoxSizer(wxVERTICAL);
 522
 523     sizerTop->Add(new wxButton(this, Except_ThrowInt, wxT("Throw &int")),
 524                   0, wxCENTRE | wxALL, 5);
 525     sizerTop->Add(new wxButton(this, Except_ThrowObject, wxT("Throw &object")),
 526                   0, wxCENTRE | wxALL, 5);
 527     sizerTop->Add(new wxButton(this, Except_Crash, wxT("&Crash")),
 528                   0, wxCENTRE | wxALL, 5);
 529     sizerTop->Add(new wxButton(this, wxID_CANCEL, wxT("&Cancel")),
 530                   0, wxCENTRE | wxALL, 5);
 531
 532     SetSizerAndFit(sizerTop);
 533 }
 534
 535 void MyDialog::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 536 {
 537     throw 17;
 538 }
 539
 540 void MyDialog::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 541 {
 542     throw MyException(wxT("Exception thrown from MyDialog"));
 543 }
 544
 545 void MyDialog::OnCrash(wxCommandEvent& WXUNUSED(event))
 546 {
 547     DoCrash();
 548 }
 549