id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
801,guard_impl objects should store references,braden,joaquintides,"{{{
In multi_index::detail::scope_guard, it seems to me that the guard_impl objects should store references to their parameters rather than copies. Consider the following code:

  T * obj = 0;
  scope_guard guard = make_guard(delete_T, obj);

  obj = create_T();

  if (obj) {
    // do stuff
  } else {
    guard.dismiss();
  }

Since make_guard passes obj by copy (and the guard_impl holds a copy), the value passed to delete_T is always 0.

This behavior can be defeated by explicitly giving make_guard a reference parameter:

  make_guard<void (*)(T*), T*&>(delete_T, obj)

However, that obviously gets quite verbose; and I don't see a downside to storing the parameters as references consistently.

}}}",Bugs,closed,,multi_index,None,,None,,