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 #endif
  47
  48 // ----------------------------------------------------------------------------
  49 // resources
  50 // ----------------------------------------------------------------------------
  51
  52 // the application icon (under Windows and OS/2 it is in resources)
  53 #if defined(__WXGTK__) || defined(__WXMOTIF__) || defined(__WXMAC__) || defined(__WXMGL__) || defined(__WXX11__)
  54     #include "../sample.xpm"
  55 #endif
  56
  57 // ----------------------------------------------------------------------------
  58 // private classes
  59 // ----------------------------------------------------------------------------
  60
  61 // Define a new application type, each program should derive a class from wxApp
  62 class MyApp : public wxApp
  63 {
  64 public:
  65     // override base class virtuals
  66     // ----------------------------
  67
  68     // program startup
  69     virtual bool OnInit();
  70
  71     // 2nd-level exception handling: we get all the exceptions occuring in any
  72     // event handler here
  73     virtual void HandleEvent(wxEvtHandler *handler,
  74                              wxEventFunction func,
  75                              wxEvent& event) const;
  76
  77     // 3rd, and final, level exception handling: whenever an unhandled
  78     // exception is caught, this function is called
  79     virtual void OnUnhandledException();
  80 };
  81
  82 // Define a new frame type: this is going to be our main frame
  83 class MyFrame : public wxFrame
  84 {
  85 public:
  86     // ctor(s)
  87     MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size,
  88             long style = wxDEFAULT_FRAME_STYLE);
  89
  90     // event handlers (these functions should _not_ be virtual)
  91     void OnQuit(wxCommandEvent& event);
  92     void OnAbout(wxCommandEvent& event);
  93     void OnDialog(wxCommandEvent& event);
  94     void OnThrowString(wxCommandEvent& event);
  95
  96     // 1st-level exception handling: we overload ProcessEvent() to be able to
  97     // catch exceptions which occur in MyFrame methods here
  98     virtual bool ProcessEvent(wxEvent& event);
  99
 100 private:
 101     // any class wishing to process wxWidgets events must use this macro
 102     DECLARE_EVENT_TABLE()
 103 };
 104
 105 // A simple dialog which has only some buttons to throw exceptions
 106 class MyDialog : public wxDialog
 107 {
 108 public:
 109     MyDialog(wxFrame *parent);
 110
 111     // event handlers
 112     void OnThrowInt(wxCommandEvent& event);
 113     void OnThrowObject(wxCommandEvent& event);
 114     void OnCrash(wxCommandEvent& event);
 115
 116 private:
 117     DECLARE_EVENT_TABLE()
 118 };
 119
 120 // A trivial exception class
 121 class MyException
 122 {
 123 public:
 124     MyException(const wxString& msg) : m_msg(msg) { }
 125
 126     const wxChar *what() const { return m_msg.c_str(); }
 127
 128 private:
 129     wxString m_msg;
 130 };
 131
 132 // ----------------------------------------------------------------------------
 133 // constants
 134 // ----------------------------------------------------------------------------
 135
 136 // IDs for the controls and the menu commands
 137 enum
 138 {
 139     // control ids
 140     Except_ThrowInt = 100,
 141     Except_ThrowObject,
 142     Except_Crash,
 143
 144     // menu items
 145     Except_ThrowString = 200,
 146     Except_Dialog,
 147
 148     Except_Quit = wxID_EXIT,
 149     Except_About = wxID_ABOUT
 150 };
 151
 152 // ----------------------------------------------------------------------------
 153 // event tables and other macros for wxWidgets
 154 // ----------------------------------------------------------------------------
 155
 156 // the event tables connect the wxWidgets events with the functions (event
 157 // handlers) which process them. It can be also done at run-time, but for the
 158 // simple menu events like this the static method is much simpler.
 159 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 160     EVT_MENU(Except_Quit,  MyFrame::OnQuit)
 161     EVT_MENU(Except_About, MyFrame::OnAbout)
 162     EVT_MENU(Except_Dialog, MyFrame::OnDialog)
 163     EVT_MENU(Except_ThrowString, MyFrame::OnThrowString)
 164 END_EVENT_TABLE()
 165
 166 BEGIN_EVENT_TABLE(MyDialog, wxDialog)
 167     EVT_BUTTON(Except_ThrowInt, MyDialog::OnThrowInt)
 168     EVT_BUTTON(Except_ThrowObject, MyDialog::OnThrowObject)
 169     EVT_BUTTON(Except_Crash, MyDialog::OnCrash)
 170 END_EVENT_TABLE()
 171
 172 // Create a new application object: this macro will allow wxWidgets to create
 173 // the application object during program execution (it's better than using a
 174 // static object for many reasons) and also implements the accessor function
 175 // wxGetApp() which will return the reference of the right type (i.e. MyApp and
 176 // not wxApp)
 177 IMPLEMENT_APP(MyApp)
 178
 179 // ============================================================================
 180 // MyApp implementation
 181 // ============================================================================
 182
 183 // 'Main program' equivalent: the program execution "starts" here
 184 bool MyApp::OnInit()
 185 {
 186     // create the main application window
 187     MyFrame *frame = new MyFrame(_T("Except wxWidgets App"),
 188                                  wxPoint(50, 50), wxSize(450, 340));
 189
 190     // and show it (the frames, unlike simple controls, are not shown when
 191     // created initially)
 192     frame->Show(true);
 193
 194     // success: wxApp::OnRun() will be called which will enter the main message
 195     // loop and the application will run. If we returned false here, the
 196     // application would exit immediately.
 197     return true;
 198 }
 199
 200 void
 201 MyApp::HandleEvent(wxEvtHandler *handler,
 202                    wxEventFunction func,
 203                    wxEvent& event) const
 204 {
 205     try
 206     {
 207         wxApp::HandleEvent(handler, func, event);
 208     }
 209     catch ( int i )
 210     {
 211         wxLogError(_T("Caught an int %d in MyApp."), i);
 212     }
 213 }
 214
 215 void MyApp::OnUnhandledException()
 216 {
 217     wxMessageBox(_T("Unhandled exception caught, program will terminate."),
 218                  _T("wxExcept Sample"), wxOK | wxICON_ERROR);
 219 }
 220
 221 // ============================================================================
 222 // MyFrame implementation
 223 // ============================================================================
 224
 225 // frame constructor
 226 MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size, long style)
 227        : wxFrame(NULL, wxID_ANY, title, pos, size, style)
 228 {
 229     // set the frame icon
 230     SetIcon(wxICON(sample));
 231
 232 #if wxUSE_MENUS
 233     // create a menu bar
 234     wxMenu *menuFile = new wxMenu;
 235     menuFile->Append(Except_Dialog, _T("Show &dialog\tCtrl-D"));
 236     menuFile->Append(Except_ThrowString, _T("Throw a &string\tCtrl-S"));
 237     menuFile->AppendSeparator();
 238     menuFile->Append(Except_Quit, _T("E&xit\tCtrl-Q"), _T("Quit this program"));
 239
 240     wxMenu *helpMenu = new wxMenu;
 241     helpMenu->Append(Except_About, _T("&About...\tF1"), _T("Show about dialog"));
 242
 243     // now append the freshly created menu to the menu bar...
 244     wxMenuBar *menuBar = new wxMenuBar();
 245     menuBar->Append(menuFile, _T("&File"));
 246     menuBar->Append(helpMenu, _T("&Help"));
 247
 248     // ... and attach this menu bar to the frame
 249     SetMenuBar(menuBar);
 250 #endif // wxUSE_MENUS
 251
 252 #if wxUSE_STATUSBAR && !defined(__WXWINCE__)
 253     // create a status bar just for fun (by default with 1 pane only)
 254     CreateStatusBar(2);
 255     SetStatusText(_T("Welcome to wxWidgets!"));
 256 #endif // wxUSE_STATUSBAR
 257 }
 258
 259 bool MyFrame::ProcessEvent(wxEvent& event)
 260 {
 261     try
 262     {
 263         return wxFrame::ProcessEvent(event);
 264     }
 265     catch ( const wxChar *msg )
 266     {
 267         wxLogMessage(_T("Caught a string \"%s\" in MyFrame"), msg);
 268
 269         return true;
 270     }
 271 }
 272
 273 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 274 {
 275     // true is to force the frame to close
 276     Close(true);
 277 }
 278
 279 void MyFrame::OnDialog(wxCommandEvent& WXUNUSED(event))
 280 {
 281     try
 282     {
 283         MyDialog dlg(this);
 284
 285         dlg.ShowModal();
 286     }
 287     catch ( ... )
 288     {
 289         Destroy();
 290         throw;
 291     }
 292 }
 293
 294 void MyFrame::OnThrowString(wxCommandEvent& WXUNUSED(event))
 295 {
 296     throw _T("some string");
 297 }
 298
 299 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 300 {
 301     wxString msg;
 302     msg.Printf( _T("This is the About dialog of the except sample.\n")
 303                 _T("Welcome to %s"), wxVERSION_STRING);
 304
 305     wxMessageBox(msg, _T("About Except"), wxOK | wxICON_INFORMATION, this);
 306 }
 307
 308 // ============================================================================
 309 // MyDialog implementation
 310 // ============================================================================
 311
 312 MyDialog::MyDialog(wxFrame *parent)
 313         : wxDialog(parent, wxID_ANY, wxString(_T("Throw exception dialog")))
 314 {
 315     wxSizer *sizerTop = new wxBoxSizer(wxVERTICAL);
 316
 317     sizerTop->Add(new wxButton(this, Except_ThrowInt, _T("Throw &int")),
 318                   0, wxCENTRE | wxALL, 5);
 319     sizerTop->Add(new wxButton(this, Except_ThrowObject, _T("Throw &object")),
 320                   0, wxCENTRE | wxALL, 5);
 321     sizerTop->Add(new wxButton(this, Except_Crash, _T("&Crash")),
 322                   0, wxCENTRE | wxALL, 5);
 323     sizerTop->Add(new wxButton(this, wxID_CANCEL, _T("&Cancel")),
 324                   0, wxCENTRE | wxALL, 5);
 325
 326     SetSizer(sizerTop);
 327     sizerTop->Fit(this);
 328 }
 329
 330 void MyDialog::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 331 {
 332     throw 17;
 333 }
 334
 335 void MyDialog::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 336 {
 337     throw MyException(_T("Exception thrown from the dialog"));
 338 }
 339
 340 void MyDialog::OnCrash(wxCommandEvent& WXUNUSED(event))
 341 {
 342     char *p = 0;
 343     strcpy(p, "Let's crash");
 344 }
 345