Question

I’m making a wrapper for a SQL database and the objects I return are shared_ptr.
I’d like to support array-type access (ie row["column"] instead of row->get("column")). The objects the shared_ptr stores support array-type access, but of course the shared_ptr doesn’t.
How should I do this with shared_ptrs, would I need to extend the class?

Answer 1

The most obvious thing is to add an operator[] to shared_ptr.
That means define your-own shared_ptr reusing std::shared_ptr and having the [] operator working the way you want.

This can be done in a quick and dirty way by deriving shared_ptr (note: shared_ptr are not polymorphic objects, so don’t mix up std:: and yours in a same context, so that you can reuse their interface).

If you are a “don’t derive if the destructor isn’t virtual” fan, than it is up to you to embed std::shared_ptr in yourptr, and rewrite the shared_ptr interface in yourptr one, delegating the functionality you have to retain.