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 classes
  60 // ----------------------------------------------------------------------------
  61
  62 // Define a new application type, each program should derive a class from wxApp
  63 class MyApp : public wxApp
  64 {
  65 public:
  66     // override base class virtuals
  67     // ----------------------------
  68
  69     // program startup
  70     virtual bool OnInit();
  71
  72     // 2nd-level exception handling: we get all the exceptions occuring in any
  73     // event handler here
  74     virtual void HandleEvent(wxEvtHandler *handler,
  75                              wxEventFunction func,
  76                              wxEvent& event) const;
  77
  78     // 3rd, and final, level exception handling: whenever an unhandled
  79     // exception is caught, this function is called
  80     virtual void OnUnhandledException();
  81 };
  82
  83 // Define a new frame type: this is going to be our main frame
  84 class MyFrame : public wxFrame
  85 {
  86 public:
  87     // ctor(s)
  88     MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size,
  89             long style = wxDEFAULT_FRAME_STYLE);
  90
  91     // event handlers (these functions should _not_ be virtual)
  92     void OnQuit(wxCommandEvent& event);
  93     void OnAbout(wxCommandEvent& event);
  94     void OnDialog(wxCommandEvent& event);
  95     void OnThrowString(wxCommandEvent& event);
  96
  97     // 1st-level exception handling: we overload ProcessEvent() to be able to
  98     // catch exceptions which occur in MyFrame methods here
  99     virtual bool ProcessEvent(wxEvent& event);
 100
 101 private:
 102     // any class wishing to process wxWidgets events must use this macro
 103     DECLARE_EVENT_TABLE()
 104 };
 105
 106 // A simple dialog which has only some buttons to throw exceptions
 107 class MyDialog : public wxDialog
 108 {
 109 public:
 110     MyDialog(wxFrame *parent);
 111
 112     // event handlers
 113     void OnThrowInt(wxCommandEvent& event);
 114     void OnThrowObject(wxCommandEvent& event);
 115     void OnCrash(wxCommandEvent& event);
 116
 117 private:
 118     DECLARE_EVENT_TABLE()
 119 };
 120
 121 // A trivial exception class
 122 class MyException
 123 {
 124 public:
 125     MyException(const wxString& msg) : m_msg(msg) { }
 126
 127     const wxChar *what() const { return m_msg.c_str(); }
 128
 129 private:
 130     wxString m_msg;
 131 };
 132
 133 // ----------------------------------------------------------------------------
 134 // constants
 135 // ----------------------------------------------------------------------------
 136
 137 // IDs for the controls and the menu commands
 138 enum
 139 {
 140     // control ids
 141     Except_ThrowInt = 100,
 142     Except_ThrowObject,
 143     Except_Crash,
 144
 145     // menu items
 146     Except_ThrowString = 200,
 147     Except_Dialog,
 148
 149     Except_Quit = wxID_EXIT,
 150     Except_About = wxID_ABOUT
 151 };
 152
 153 // ----------------------------------------------------------------------------
 154 // event tables and other macros for wxWidgets
 155 // ----------------------------------------------------------------------------
 156
 157 // the event tables connect the wxWidgets events with the functions (event
 158 // handlers) which process them. It can be also done at run-time, but for the
 159 // simple menu events like this the static method is much simpler.
 160 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 161     EVT_MENU(Except_Quit,  MyFrame::OnQuit)
 162     EVT_MENU(Except_About, MyFrame::OnAbout)
 163     EVT_MENU(Except_Dialog, MyFrame::OnDialog)
 164     EVT_MENU(Except_ThrowString, MyFrame::OnThrowString)
 165 END_EVENT_TABLE()
 166
 167 BEGIN_EVENT_TABLE(MyDialog, wxDialog)
 168     EVT_BUTTON(Except_ThrowInt, MyDialog::OnThrowInt)
 169     EVT_BUTTON(Except_ThrowObject, MyDialog::OnThrowObject)
 170     EVT_BUTTON(Except_Crash, MyDialog::OnCrash)
 171 END_EVENT_TABLE()
 172
 173 // Create a new application object: this macro will allow wxWidgets to create
 174 // the application object during program execution (it's better than using a
 175 // static object for many reasons) and also implements the accessor function
 176 // wxGetApp() which will return the reference of the right type (i.e. MyApp and
 177 // not wxApp)
 178 IMPLEMENT_APP(MyApp)
 179
 180 // ============================================================================
 181 // MyApp implementation
 182 // ============================================================================
 183
 184 // 'Main program' equivalent: the program execution "starts" here
 185 bool MyApp::OnInit()
 186 {
 187     // create the main application window
 188     MyFrame *frame = new MyFrame(_T("Except wxWidgets App"),
 189                                  wxPoint(50, 50), wxSize(450, 340));
 190
 191     // and show it (the frames, unlike simple controls, are not shown when
 192     // created initially)
 193     frame->Show(true);
 194
 195     // success: wxApp::OnRun() will be called which will enter the main message
 196     // loop and the application will run. If we returned false here, the
 197     // application would exit immediately.
 198     return true;
 199 }
 200
 201 void
 202 MyApp::HandleEvent(wxEvtHandler *handler,
 203                    wxEventFunction func,
 204                    wxEvent& event) const
 205 {
 206     try
 207     {
 208         wxApp::HandleEvent(handler, func, event);
 209     }
 210     catch ( int i )
 211     {
 212         wxLogError(_T("Caught an int %d in MyApp."), i);
 213     }
 214 }
 215
 216 void MyApp::OnUnhandledException()
 217 {
 218     wxMessageBox(_T("Unhandled exception caught, program will terminate."),
 219                  _T("wxExcept Sample"), wxOK | wxICON_ERROR);
 220 }
 221
 222 // ============================================================================
 223 // MyFrame implementation
 224 // ============================================================================
 225
 226 // frame constructor
 227 MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size, long style)
 228        : wxFrame(NULL, wxID_ANY, title, pos, size, style)
 229 {
 230     // set the frame icon
 231     SetIcon(wxICON(sample));
 232
 233 #if wxUSE_MENUS
 234     // create a menu bar
 235     wxMenu *menuFile = new wxMenu;
 236     menuFile->Append(Except_Dialog, _T("Show &dialog\tCtrl-D"));
 237     menuFile->Append(Except_ThrowString, _T("Throw a &string\tCtrl-S"));
 238     menuFile->AppendSeparator();
 239     menuFile->Append(Except_Quit, _T("E&xit\tCtrl-Q"), _T("Quit this program"));
 240
 241     wxMenu *helpMenu = new wxMenu;
 242     helpMenu->Append(Except_About, _T("&About...\tF1"), _T("Show about dialog"));
 243
 244     // now append the freshly created menu to the menu bar...
 245     wxMenuBar *menuBar = new wxMenuBar();
 246     menuBar->Append(menuFile, _T("&File"));
 247     menuBar->Append(helpMenu, _T("&Help"));
 248
 249     // ... and attach this menu bar to the frame
 250     SetMenuBar(menuBar);
 251 #endif // wxUSE_MENUS
 252
 253 #if wxUSE_STATUSBAR && !defined(__WXWINCE__)
 254     // create a status bar just for fun (by default with 1 pane only)
 255     CreateStatusBar(2);
 256     SetStatusText(_T("Welcome to wxWidgets!"));
 257 #endif // wxUSE_STATUSBAR
 258 }
 259
 260 bool MyFrame::ProcessEvent(wxEvent& event)
 261 {
 262     try
 263     {
 264         return wxFrame::ProcessEvent(event);
 265     }
 266     catch ( const wxChar *msg )
 267     {
 268         wxLogMessage(_T("Caught a string \"%s\" in MyFrame"), msg);
 269
 270         return true;
 271     }
 272 }
 273
 274 void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
 275 {
 276     // true is to force the frame to close
 277     Close(true);
 278 }
 279
 280 void MyFrame::OnDialog(wxCommandEvent& WXUNUSED(event))
 281 {
 282     try
 283     {
 284         MyDialog dlg(this);
 285
 286         dlg.ShowModal();
 287     }
 288     catch ( ... )
 289     {
 290         Destroy();
 291         throw;
 292     }
 293 }
 294
 295 void MyFrame::OnThrowString(wxCommandEvent& WXUNUSED(event))
 296 {
 297     throw _T("some string");
 298 }
 299
 300 void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 301 {
 302     wxString msg;
 303     msg.Printf( _T("This is the About dialog of the except sample.\n")
 304                 _T("Welcome to %s"), wxVERSION_STRING);
 305
 306     wxMessageBox(msg, _T("About Except"), wxOK | wxICON_INFORMATION, this);
 307 }
 308
 309 // ============================================================================
 310 // MyDialog implementation
 311 // ============================================================================
 312
 313 MyDialog::MyDialog(wxFrame *parent)
 314         : wxDialog(parent, wxID_ANY, wxString(_T("Throw exception dialog")))
 315 {
 316     wxSizer *sizerTop = new wxBoxSizer(wxVERTICAL);
 317
 318     sizerTop->Add(new wxButton(this, Except_ThrowInt, _T("Throw &int")),
 319                   0, wxCENTRE | wxALL, 5);
 320     sizerTop->Add(new wxButton(this, Except_ThrowObject, _T("Throw &object")),
 321                   0, wxCENTRE | wxALL, 5);
 322     sizerTop->Add(new wxButton(this, Except_Crash, _T("&Crash")),
 323                   0, wxCENTRE | wxALL, 5);
 324     sizerTop->Add(new wxButton(this, wxID_CANCEL, _T("&Cancel")),
 325                   0, wxCENTRE | wxALL, 5);
 326
 327     SetSizer(sizerTop);
 328     sizerTop->Fit(this);
 329 }
 330
 331 void MyDialog::OnThrowInt(wxCommandEvent& WXUNUSED(event))
 332 {
 333     throw 17;
 334 }
 335
 336 void MyDialog::OnThrowObject(wxCommandEvent& WXUNUSED(event))
 337 {
 338     throw MyException(_T("Exception thrown from the dialog"));
 339 }
 340
 341 void MyDialog::OnCrash(wxCommandEvent& WXUNUSED(event))
 342 {
 343     char *p = 0;
 344     strcpy(p, "Let's crash");
 345 }
 346