"Martin Bosticky" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Hi > > Me and my colleagues have come across an issue when using a shared_ptr. > > void myFunction(shared_ptr<myClass> const & vp_Pointer) > { > vp_Pointer->call any non-const function > } > > i.e. a const shared_ptr doesn't prevent anyone from changing the > contents to which the pointer points. This makes sense as it behaves > like a normal pointer.
That's the idea. > > However, how can I pass a shared pointer into a function such that the > data can not be modified? i.e. how can I pass an equivalent of "myClass > const *" ? > > I tried static casting to shared_ptr<const myClass> which works but > causes a new constructor to be called which means I loose the efficiency > of passing by reference. This would be the right way to do it. > > Any comments of suggestions would be greatly appreciated. If you really have a performance problem here (so you're probably counting processor cycles) you can always try reinterpret_cast :-) shared_ptr<myClass> ptr (new myClass); my_function (reinterpret_cast<shared_ptr<myClass const> &>(ptr)); Of course, this uses undefined behaviour, but it is reasonable to assume that the const/non-const representations are actually identical. I wouldn't do it myself, but then I don't have to count processor cycles, either. -- Raoul Gough see http://home.clara.net/raoulgough/ for my work availability _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
