lazy_init

For lazy initialization:

std::shared_ptr<some_resource> resource_ptr;
std::once_flag resource_flag; 
void init_resource()
{
  resource_ptr.reset(new some_resource); 
}
void foo()
{
  std::call_once(resource_flag,init_resource); 
  resource_ptr->do_something();
}

Class object

class X
{
private:
  connection_info connection_details;
  connection_handle connection;
  std::once_flag connection_init_flag;
  void open_connection()
  {
    connection=connection_manager.open(connection_details);
  }
public:
  X(connection_info const& connection_details_):
    connection_details(connection_details_)
  {}
  void send_data(data_packet const& data) 
  {
    std::call_once(connection_init_flag,&X::open_connection,this); 
    connection.send_data(data);
  }
  data_packet receive_data() 
  {
    std::call_once(connection_init_flag,&X::open_connection,this); 
    return connection.receive_data();
  }
};