36c9828f70
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51911 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
77 lines
3.6 KiB
C
77 lines
3.6 KiB
C
/////////////////////////////////////////////////////////////////////////////
|
|
// Name: exceptions
|
|
// Purpose: topic overview
|
|
// Author: wxWidgets team
|
|
// RCS-ID: $Id$
|
|
// Licence: wxWindows license
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
|
|
/*!
|
|
|
|
@page exceptions_overview C++ exceptions overview
|
|
|
|
#Introduction
|
|
@ref exceptionstrategies_overview
|
|
#Technicalities
|
|
|
|
|
|
@section exceptionintroduction Introduction
|
|
|
|
wxWidgets had been started long before the exceptions were introduced in C++ so
|
|
it is not very surprising that it is not built around using them as some more
|
|
modern C++ libraries are. For instance, the library doesn't throw exceptions to
|
|
signal about the errors. Moreover, up to (and including) the version 2.4 of
|
|
wxWidgets, even using the exceptions in the user code was dangerous because the
|
|
library code wasn't exception-safe and so an exception propagating through it
|
|
could result in memory and/or resource leaks, and also not very convenient.
|
|
Starting from the version 2.5.1 wxWidgets becomes more exception-friendly. It
|
|
still doesn't use the exceptions by itself but it should be now safe to use the
|
|
exceptions in the user code and the library tries to help you with this. Please
|
|
note that making the library exception-safe is still work in progress.
|
|
|
|
|
|
@section exceptionstrategies Strategies for exceptions handling
|
|
|
|
There are several choice for using the exceptions in wxWidgets programs. First
|
|
of all, you may not use them at all. As stated above, the library doesn't throw
|
|
any exceptions by itself and so you don't have to worry about exceptions at all
|
|
unless your own code throws them. This is, of course, the simplest solution but
|
|
may be not the best one to deal with all possible errors.
|
|
Another strategy is to use exceptions only to signal truly fatal errors. In
|
|
this case you probably don't expect to recover from them and the default
|
|
behaviour -- to simply terminate the program -- may be appropriate. If it is
|
|
not, you may override #OnUnhandledException()
|
|
in your wxApp-derived class to perform any clean up tasks. Note, however, that
|
|
any information about the exact exception type is lost when this function is
|
|
called, so if you need you should override #OnRun() and
|
|
add a try/catch clause around the call of the base class version. This would
|
|
allow you to catch any exceptions generated during the execution of the main
|
|
event loop. To deal with the exceptions which may arise during the program
|
|
startup and/or shutdown you should insert try/catch clauses in
|
|
#OnInit() and/or #OnExit() as well.
|
|
Finally, you may also want to continue running even when certain exceptions
|
|
occur. If all of your exceptions may happen only in the event handlers of a
|
|
single class (or only in the classes derived from it), you may centralize your
|
|
exception handling code in #ProcessEvent
|
|
method of this class. If this is impractical, you may also consider overriding
|
|
the wxApp::HandleEvent() which allows you to handle
|
|
all the exceptions thrown by any event handler.
|
|
|
|
|
|
@section exceptionstechnicalities Technicalities
|
|
|
|
To use any kind of exception support in the library you need to build it with
|
|
@c wxUSE_EXCEPTIONS set to 1. This should be the case by default but
|
|
if it isn't, you should edit the @c include/wx/msw/setup.h file under
|
|
Windows or run @c configure with @c --enable-exceptions argument
|
|
under Unix.
|
|
On the other hand, if you do not plan to use exceptions, setting this
|
|
flag to 0 or using @c --disable-exceptions could result in a leaner and
|
|
slightly faster library.
|
|
As for any other library feature, there is a #sample
|
|
showing how to use it. Please look at its sources for further information.
|
|
|
|
*/
|
|
|
|
|