Re: [Boost-users] boost::any and const pointers

On Wed, Dec 2, 2009 at 10:55 AM, James C. Sutherland wrote:

int main() {  Properties p;  int i=1;  set(p,"int",i);  set(p,"int*",&i);

 int*       j = get(p,"int*");  // I don't want this to compile  const int* k = get(p,"int*");  // I want this to compile fine. }

Currently this whole code compiles without trouble, but I don't want to allow a non-const pointer to be extracted.  Any ideas of how to accomplish this?

Thanks not possible AFAIK. The first compiles alright, but will fail at runtime because the boost::any was constructed using a const int*. By design all extractions are checked at runtime only, and the typeid()/std::type_info of what you put in and what you try to get it as must be the same. Given your code, you can't even do get<int>(p, "int"), because a const int was put in, not an int (see your set() impl), and typeid(int) != typeid(const int). --DD