Re: auto_ptr vs. boost shared_ptr

From: (Carl Barron)
17 Jul 2006 16:02:16 -0400
James Kanze <> wrote:

   vector< shared_ptr< int > > v1; // OK.
   vector< auto_ptr< int > > v2; // Undefined Behavior, but probably a
compile error.

True, but most of the time, I find that raw pointers are best
here. Of course, I usually use the Boehm collector, so I don't
need a surrogate for garbage collection.

  Does your GC handle things like
  struct larger_than_10
      bool operator () (int *p) {return *p > 10;}
  struct create_ptr()
        int i;
        int * operator () () {return new int(i++);}
  struct kill
       void operator () (int *x) {delete x;}
  int main()
        std::vector<int *> data;

        std::vector<int *>::iterator last =

 remove_if blindly overwrites the int *'s so the deleted ones are either
never deleted until the os takes over, or are deleted mutliple times.
fine of the int *'s are not on the heap but statically allocated but
it is a pitfall someone that does not examine the actual code of
remove_if will not think of.

// For is a forward iterator.
template <class For,class Pred>
For remove_if(For begin,For end, Rred pred)
    For last(begin);
    while(begin != end)
           *last = *begin;
    return last;

looks like a reference implementation to me of remove_if. If your GC
handles overwrites like this, its ok, but using raw ptrs in any stl
container is a recipe for disaster, if the access to the container is
not controlled, and kept away from the 'user'.

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