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