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