README.qtcopy: -no-stl or no -no-stl?
l.lunak at suse.cz
Wed Jan 21 09:24:53 GMT 2004
On Tuesday 20 of January 2004 20:34, Bo Thorsen wrote:
> On Tuesday 20 January 2004 14:51, Dirk Mueller wrote:
> > On Tuesday 20 January 2004 10:30, Bo Thorsen wrote:
> > > cripple peoples Qt, when they might download Qt apps that need
> > > exceptions. And yes, there are examples of such apps.
> > Might be a stupid question, but why do you expect that Qt would do
> > anything with exceptions?
> > it is still fine to compile Qt without exceptions support. If you want
> > exceptions fine - use them. But don't expect that Qt makes use of them.
> > what do you think what will happen when exceptions cross signal/slot
> > borders, even when Qt is compiled with exception support? Qt does not
> > handle any exceptions at all, so letting them pass through Qt is
> > probably producing very unwanted things.
> > And if you don't pass the exceptions through Qt - you can compile Qt
> > without exceptions support. Thats why we recommend it.
> Just throw an exception in a slot, or something that is called from a
> slot. Qt without exception support crashes. Qt with exception support
> handles this nicely.
> Or throw an exception in any of the template methods Qt has for
> overriding, with the same results.
> Or subclass a Qt class, and override something that's called by a
> non-overridden method...
> There are so many ways to crash Qt if you use exceptions but have a Qt
> without it. And they are all fixed by not using that old workaround.
I think what Dirk was trying to say was that just removing -fno-exceptions is
not going to magically make Qt exceptions aware. Qt code won't generally
expect an exception to be thrown, and may leak resources or misbehave. Just
e.g. have a look at QObject::activate_signal() and start counting things that
may go wrong. Before fixing at least the parts where exceptions are most
likely there's no point in compiling Qt with exceptions enabled.
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