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