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