Re: [boost] shared_ptr question

22 Jun 2005


      Rob Stewart wrote:
...
From: H <h.v.niekerk@hccnet.nl>
...
Martin Bonner wrote:
...
From: H. van Niekerk [mailto:h.v.niekerk@hccnet.nl]
Incidentally, I don't think the presence of three .cpp files is directly
relevent.  I suspect that the relevent factor is that you have three
*functions*, and your problem is passing the data between them.
Thank you for your response. I hope the code below explains more:
Master.cpp
{
  Client c;
  c.readFromSatellite(input);
  cout << "input = " << input << endl;
}
Client.cpp
{
  Satellite s;
readFromSatellite(input)
  {
      s.readFromInterface(input);
      return input;
  }
}
Satellite.cpp
{
  readFromInterface(input)
  {
      // Here the actual reading is done
      fti->writeAndReadAllData(output, input);
      return input;
  }
}
As Martin said, the separate files aren't relevant.  Also, the
usage and declarations of your functions aren't consistent.
Let's see if I can recast your problem to something a little
simpler to discuss:
void function2(some_type data) // stores stuff in caller's object
   {
      read_something_from_somewhere(data);
   }
void function1(some_type data) // stores stuff in caller's object
   {
      function2(data);
   }
void function3(some_type data)
   {
      // do something useful with data
   }
int main()
   {
      some_type data; // some pointer type
      function1(data); // stores stuff in data
      function3(data);
   }
Is that a good approximation of what you want?
If so, some_type should be boost::shared_ptr<something> and the
rest should just work.  Of course, you can avoid using
boost::shared_ptr if function1() and function2() take non-const
references to some_type:
void function2(some_type & data) // stores stuff in caller's object
   {
      read_something_from_somewhere(data);
   }
void function1(some_type & data) // stores stuff in caller's object
   {
      function2(data);
   }
void function3(some_type const & data)
   {
      // do something useful with data
   }
int main()
   {
      some_type data; // not a pointer type
      function1(data); // stores stuff in data
      function3(data);
   }
After reviewing the groups on this news-server, I think I'm posting to 
the wrong group. If you agree with that view, please let me know. I'll 
follow up to the user group then.

H.