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 // Copyright:   (c) 2003-2005 Vadim Zeitlin
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // For compilers that support precompilation, includes "wx/wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #ifdef __BORLANDC__
  23     #pragma hdrstop
  24 #endif
  25
  26 #if !wxUSE_EXCEPTIONS
  27     #error "This sample only works with wxUSE_EXCEPTIONS == 1"
  28 #endif // !wxUSE_EXCEPTIONS
  29
  30 // for all others, include the necessary headers (this file is usually all you
  31 // need because it includes almost all "standard" wxWidgets headers)
  32 #ifndef WX_PRECOMP
  33     #include "wx/log.h"
  34
  35     #include "wx/app.h"
  36     #include "wx/frame.h"
  37     #include "wx/dialog.h"
  38     #include "wx/menu.h"
  39
  40     #include "wx/button.h"
  41     #include "wx/sizer.h"
  42
  43     #include "wx/utils.h"
  44     #include "wx/msgdlg.h"
  45     #include "wx/icon.h"
  46
  47     #include "wx/thread.h"
  48 #endif
  49
  50 // ----------------------------------------------------------------------------
  51 // resources
  52 // ----------------------------------------------------------------------------
  53
  54 // the application icon (under Windows and OS/2 it is in resources)
  55 #ifndef wxHAS_IMAGES_IN_RESOURCES
  56     #include "../sample.xpm"
  57 #endif
  58
  59 // ----------------------------------------------------------------------------
  60 // private functions
  61 // ----------------------------------------------------------------------------
  62
  63 static void DoCrash()
  64 {
  65     char *p = 0;
  66     strcpy(p, "Let's crash");
  67 }
  68
  69 // ----------------------------------------------------------------------------
  70 // private classes
  71 // ----------------------------------------------------------------------------
  72
  73 // Define a new application type, each program should derive a class from wxApp
  74 class MyApp : public wxApp
  75 {
  76 public:
  77     // override base class virtuals
  78     // ----------------------------
  79
  80     // program startup
  81     virtual bool OnInit();
  82
  83     // 2nd-level exception handling: we get all the exceptions occurring in any
  84     // event handler here
  85     virtual bool OnExceptionInMainLoop();
  86
  87     // 3rd, and final, level exception handling: whenever an unhandled
  88     // exception is caught, this function is called
  89     virtual void OnUnhandledException();
  90
  91     // and now for something different: this function is called in case of a
  92     // crash (e.g. dereferencing null pointer, division by 0, ...)
  93     virtual void OnFatalException();
  94
  95     // you can override this function to do something different (e.g. log the
  96     // assert to file) whenever an assertion fails
  97     virtual void OnAssertFailure(const wxChar *file,
  98                                  int line,
  99                                  const wxChar *func,
 100                                  const wxChar *cond,
 101                                  const wxChar *msg);
 102 };
 103
 104 // Define a new frame type: this is going to be our main frame
 105 class MyFrame : public wxFrame
 106 {
 107 public:
 108     // ctor(s)
 109     MyFrame();
 110
 111     // event handlers (these functions should _not_ be virtual)
 112     void OnQuit(wxCommandEvent& event);
 113     void OnAbout(wxCommandEvent& event);
 114     void OnDialog(wxCommandEvent& event);
 115
 116     void OnThrowInt(wxCommandEvent& event);
 117     void OnThrowString(wxCommandEvent& event);
 118     void OnThrowObject(wxCommandEvent& event);
 119     void OnThrowUnhandled(wxCommandEvent& event);
 120
 121     void OnCrash(wxCommandEvent& event);
 122     void OnTrap(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     Except_Trap,
 192 #if wxUSE_ON_FATAL_EXCEPTION
 193     Except_HandleCrash,
 194 #endif // wxUSE_ON_FATAL_EXCEPTION
 195     Except_ShowAssert,
 196 #if wxUSE_THREADS
 197     Except_ShowAssertInThread,
 198 #endif // wxUSE_THREADS
 199     Except_Dialog,
 200
 201     Except_Quit = wxID_EXIT,
 202     Except_About = wxID_ABOUT
 203 };
 204
 205 // ----------------------------------------------------------------------------
 206 // event tables and other macros for wxWidgets
 207 // ----------------------------------------------------------------------------
 208
 209 // the event tables connect the wxWidgets events with the functions (event
 210 // handlers) which process them. It can be also done at run-time, but for the
 211 // simple menu events like this the static method is much simpler.
 212 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 213     EVT_MENU(Except_Quit,  MyFrame::OnQuit)
 214     EVT_MENU(Except_About, MyFrame::OnAbout)
 215     EVT_MENU(Except_Dialog, MyFrame::OnDialog)
 216     EVT_MENU(Except_ThrowInt, MyFrame::OnThrowInt)
 217     EVT_MENU(Except_ThrowString, MyFrame::OnThrowString)
 218     EVT_MENU(Except_ThrowObject, MyFrame::OnThrowObject)
 219     EVT_MENU(Except_ThrowUnhandled, MyFrame::OnThrowUnhandled)
 220     EVT_MENU(Except_Crash, MyFrame::OnCrash)
 221     EVT_MENU(Except_Trap, MyFrame::OnTrap)
 222 #if wxUSE_ON_FATAL_EXCEPTION
 223     EVT_MENU(Except_HandleCrash, MyFrame::OnHandleCrash)
 224 #endif // wxUSE_ON_FATAL_EXCEPTION
 225     EVT_MENU(Except_ShowAssert, MyFrame::OnShowAssert)
 226 #if wxUSE_THREADS
 227     EVT_MENU(Except_ShowAssertInThread, MyFrame::OnShowAssertInThread)
 228 #endif // wxUSE_THREADS
 229 END_EVENT_TABLE()
 230
 231 BEGIN_EVENT_TABLE(MyDialog, wxDialog)
 232     EVT_BUTTON(Except_ThrowInt, MyDialog::OnThrowInt)
 233     EVT_BUTTON(Except_ThrowObject, MyDialog::OnThrowObject)
 234     EVT_BUTTON(Except_Crash, MyDialog::OnCrash)
 235 END_EVENT_TABLE()
 236
 237 // Create a new application object: this macro will allow wxWidgets to create
 238 // the application object during program execution (it's better than using a
 239 // static object for many reasons) and also implements the accessor function
 240 // wxGetApp() which will return the reference of the right type (i.e. MyApp and
 241 // not wxApp)
 242 IMPLEMENT_APP(MyApp)
 243
 244 // ============================================================================
 245 // MyApp implementation
 246 // ============================================================================
 247
 248 // 'Main program' equivalent: the program execution "starts" here
 249 bool MyApp::OnInit()
 250 {
 251     if ( !wxApp::OnInit() )
 252         return false;
 253
 254     // create the main application window
 255     MyFrame *frame = new MyFrame();
 256
 257     // and show it (the frames, unlike simple controls, are not shown when
 258     // created initially)
 259     frame->Show(true);
 260
 261     // success: wxApp::OnRun() will be called which will enter the main message
 262     // loop and the application will run. If we returned false here, the
 263     // application would exit immediately.
 264     return true;
 265 }
 266
 267 bool MyApp::OnExceptionInMainLoop()
 268 {
 269     try
 270     {
 271         throw;
 272     }
 273     catch ( int i )
 274     {
 275         wxLogWarning(wxT("Caught an int %d in MyApp."), i);
 276     }
 277     catch ( MyException& e )
 278     {
 279         wxLogWarning(wxT("Caught MyException(%s) in MyApp."), e.what());
 280     }
 281     catch ( ... )
 282     {
 283         throw;
 284     }
 285
 286     return true;
 287 }
 288
 289 void MyApp::OnUnhandledException()
 290 {
 291     // this shows how we may let some exception propagate uncaught
 292     try
 293     {
 294         throw;
 295     }
 296     catch ( UnhandledException& )
 297     {
 298         throw;
 299     }
 300     catch ( ... )
 301     {
 302         wxMessageBox(wxT("Unhandled exception caught, program will terminate."),
 303                      wxT("wxExcept Sample"), wxOK | wxICON_ERROR);
 304     }
 305 }
 306
 307 void MyApp::OnFatalException()
 308 {
 309     wxMessageBox(wxT("Program has crashed and will terminate."),
 310                  wxT("wxExcept Sample"), wxOK | wxICON_ERROR);
 311 }
 312
 313 void MyApp::OnAssertFailure(const wxChar *file,
 314                             int line,
 315                             const wxChar *func,
 316                             const wxChar *cond,
 317                             const wxChar *msg)
 318 {
 319     // take care to not show the message box from a worker thread, this doesn't
 320     // work as it doesn't have any event loop
 321     if ( !wxIsMainThread() ||
 322             wxMessageBox
 323             (
 324                 wxString::Format("An assert failed in %s().", func) +
 325                 "\n"
 326                 "Do you want to call the default assert handler?",
 327                 "wxExcept Sample",
 328                 wxYES_NO | wxICON_QUESTION
 329             ) == wxYES )
 330     {
 331         wxApp::OnAssertFailure(file, line, func, cond, msg);
 332     }
 333 }
 334
 335 // ============================================================================
 336 // MyFrame implementation
 337 // ============================================================================
 338
 339 // frame constructor
 340 MyFrame::MyFrame()
 341        : wxFrame(NULL, wxID_ANY, wxT("Except wxWidgets App"),
 342                  wxPoint(50, 50), wxSize(450, 340))
 343 {
 344     // set the frame icon
 345     SetIcon(wxICON(sample));
 346
 347 #if wxUSE_MENUS
 348     // create a menu bar
 349     wxMenu *menuFile = new wxMenu;
 350     menuFile->Append(Except_Dialog, wxT("Show &dialog\tCtrl-D"));
 351     menuFile->AppendSeparator();
 352     menuFile->Append(Except_ThrowInt, wxT("Throw an &int\tCtrl-I"));
 353     menuFile->Append(Except_ThrowString, wxT("Throw a &string\tCtrl-S"));
 354     menuFile->Append(Except_ThrowObject, wxT("Throw an &object\tCtrl-O"));
 355     menuFile->Append(Except_ThrowUnhandled,
 356                         wxT("Throw &unhandled exception\tCtrl-U"));
 357     menuFile->Append(Except_Crash, wxT("&Crash\tCtrl-C"));
 358     menuFile->Append(Except_Trap, "&Trap\tCtrl-T",
 359                      "Break into the debugger (if one is running)");
 360     menuFile->AppendSeparator();
 361 #if wxUSE_ON_FATAL_EXCEPTION
 362     menuFile->AppendCheckItem(Except_HandleCrash, wxT("&Handle crashes\tCtrl-H"));
 363     menuFile->AppendSeparator();
 364 #endif // wxUSE_ON_FATAL_EXCEPTION
 365     menuFile->Append(Except_ShowAssert, wxT("Provoke &assert failure\tCtrl-A"));
 366 #if wxUSE_THREADS
 367     menuFile->Append(Except_ShowAssertInThread,
 368                      wxT("Assert failure in &thread\tShift-Ctrl-A"));
 369 #endif // wxUSE_THREADS
 370     menuFile->AppendSeparator();
 371     menuFile->Append(Except_Quit, wxT("E&xit\tCtrl-Q"), wxT("Quit this program"));
 372
 373     wxMenu *helpMenu = new wxMenu;
 374     helpMenu->Append(Except_About, wxT("&About\tF1"), wxT("Show about dialog"));
 375
 376     // now append the freshly created menu to the menu bar...
 377     wxMenuBar *menuBar = new wxMenuBar();
 378     menuBar->Append(menuFile, wxT("&File"));
 379     menuBar->Append(helpMenu, wxT("&Help"));
 380
 381     // ... and attach this menu bar to the frame
 382     SetMenuBar(menuBar);
 383 #endif // wxUSE_MENUS
 384
 385 #if wxUSE_STATUSBAR && !defined(__WXWINCE__)
 386     // create a status bar just for fun (by default with 1 pane only)
 387     CreateStatusBar(2);
 388     SetStatusText(wxT("Welcome to wxWidgets!"));
 389 #endif // wxUSE_STATUSBAR
 390 }
 391
 392 bool MyFrame::ProcessEvent(wxEvent& event)
 393 {
 394     try
 395     {
 396         return wxFrame::ProcessEvent(event);
 397     }
 398     catch ( const wxChar *msg )
 399     {
 400         wxLogMessage(wxT("Caught a string \"%s\" in MyFrame"), msg);
 401
 402         return true;
 403     }
 404 }
 405
 406 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 407 {
 408     // true is to force the frame to close
 409     Close(true);
 410 }
 411
 412 void MyFrame::OnDialog(wxCommandEvent& WXUNUSED(event))
 413 {
 414     try
 415     {
 416         MyDialog dlg(this);
 417
 418         dlg.ShowModal();
 419     }
 420     catch ( ... )
 421     {
 422         wxLogWarning(wxT("An exception in MyDialog"));
 423
 424         Destroy();
 425         throw;
 426     }
 427 }
 428
 429 void MyFrame::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 430 {
 431     throw -17;
 432 }
 433
 434 void MyFrame::OnThrowString(wxCommandEvent& WXUNUSED(event))
 435 {
 436     throw wxT("string thrown from MyFrame");
 437 }
 438
 439 void MyFrame::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 440 {
 441     throw MyException(wxT("Exception thrown from MyFrame"));
 442 }
 443
 444 void MyFrame::OnThrowUnhandled(wxCommandEvent& WXUNUSED(event))
 445 {
 446     throw UnhandledException();
 447 }
 448
 449 void MyFrame::OnCrash(wxCommandEvent& WXUNUSED(event))
 450 {
 451     DoCrash();
 452 }
 453
 454 void MyFrame::OnTrap(wxCommandEvent& WXUNUSED(event))
 455 {
 456     wxTrap();
 457 }
 458
 459 #if wxUSE_ON_FATAL_EXCEPTION
 460
 461 void MyFrame::OnHandleCrash(wxCommandEvent& event)
 462 {
 463     wxHandleFatalExceptions(event.IsChecked());
 464 }
 465
 466 #endif // wxUSE_ON_FATAL_EXCEPTION
 467
 468 void MyFrame::OnShowAssert(wxCommandEvent& WXUNUSED(event))
 469 {
 470     // provoke an assert from wxArrayString
 471     wxArrayString arr;
 472     arr[0];
 473 }
 474
 475 #if wxUSE_THREADS
 476
 477 void MyFrame::OnShowAssertInThread(wxCommandEvent& WXUNUSED(event))
 478 {
 479     class AssertThread : public wxThread
 480     {
 481     public:
 482         AssertThread()
 483             : wxThread(wxTHREAD_JOINABLE)
 484         {
 485         }
 486
 487     protected:
 488         virtual void *Entry()
 489         {
 490             wxFAIL_MSG("Test assert in another thread.");
 491
 492             return 0;
 493         }
 494     };
 495
 496     AssertThread thread;
 497     thread.Create();
 498     thread.Run();
 499     thread.Wait();
 500 }
 501
 502 #endif // wxUSE_THREADS
 503
 504 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 505 {
 506     wxString msg;
 507     msg.Printf( wxT("This is the About dialog of the except sample.\n")
 508                 wxT("Welcome to %s"), wxVERSION_STRING);
 509
 510     wxMessageBox(msg, wxT("About Except"), wxOK | wxICON_INFORMATION, this);
 511 }
 512
 513 // ============================================================================
 514 // MyDialog implementation
 515 // ============================================================================
 516
 517 MyDialog::MyDialog(wxFrame *parent)
 518         : wxDialog(parent, wxID_ANY, wxString(wxT("Throw exception dialog")))
 519 {
 520     wxSizer *sizerTop = new wxBoxSizer(wxVERTICAL);
 521
 522     sizerTop->Add(new wxButton(this, Except_ThrowInt, wxT("Throw &int")),
 523                   0, wxCENTRE | wxALL, 5);
 524     sizerTop->Add(new wxButton(this, Except_ThrowObject, wxT("Throw &object")),
 525                   0, wxCENTRE | wxALL, 5);
 526     sizerTop->Add(new wxButton(this, Except_Crash, wxT("&Crash")),
 527                   0, wxCENTRE | wxALL, 5);
 528     sizerTop->Add(new wxButton(this, wxID_CANCEL, wxT("&Cancel")),
 529                   0, wxCENTRE | wxALL, 5);
 530
 531     SetSizerAndFit(sizerTop);
 532 }
 533
 534 void MyDialog::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 535 {
 536     throw 17;
 537 }
 538
 539 void MyDialog::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 540 {
 541     throw MyException(wxT("Exception thrown from MyDialog"));
 542 }
 543
 544 void MyDialog::OnCrash(wxCommandEvent& WXUNUSED(event))
 545 {
 546     DoCrash();
 547 }
 548