Hans Aberg wrote: > With unions, the problem is, if con-/de-structors are non-trivial, that it > is impossible to know which ones to apply and when.
Stroustrup, _The C++ Programming Language_, Special Edition, 2000, p. 257, Section 10.4.12: "Consequently, a union may not have members with constructors or destructors. It wouldn't be possible to protect that object against corruption or to guarantee that the right destructor is called when the union goes out of scope." > The union does not > contain any type information which field is selected. If one adds that, > unions with non-trivial con-/de-Structors would be possible. Add it where? I suspect that doing so in C++ would break compatibility to C. I haven't checked whether any C++ implementation has implemented such a facility as an extension, though. It might be possible to implement a way of using class types with constructors and destructors in a `%union' in Bison, but not with an unextended C or C++ union. This is just my opinion, but I think it's simpler to just use `void*'. Laurence _______________________________________________ Help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
