The Standard Librarian: I/O and Function Objects: Containers of Pointers
By Matthew H. Austern, October 01, 2001
Containers of pointers are common and important. Unfortunately, they are also widely misunderstood. This column explains how containers of pointers behave, when containers of pointers are useful, and what techniques you can use to manage them.
October 2001 C++ Experts Forum/The Standard Librarian/Listing 1
#include <vector>
class arena {
private:
struct holder {
virtual ~holder() { }
};
template <class T>
struct obj_holder : public holder {
T obj;
template <class Arg1>
obj_holder(Arg1 arg1)
: obj(arg1) { }
};
std::vector<holder*> owned;
private:
arena(const arena&);
void operator=(const arena&);
public:
arena() { }
~arena() {
destroy_all();
}
template <class T, class Arg1>
T* create(Arg1 arg1) {
obj_holder<T>* p = new obj_holder<T>(arg1);
owned.push_back(p);
return &p->obj;
}
void destroy_all() {
std::vector<holder*>::size_type i = 0;
while (i < owned.size()) {
delete owned[i];
++i;
}
owned.clear();
}
};
