Re: [boost] shared_ptr question

From: Rob Stewart (stewart_at_[hidden])
Date: 2005-06-21 15:20:50

From: H <h.v.niekerk_at_[hidden]>
> Martin Bonner wrote:
> > From: H. van Niekerk [mailto:h.v.niekerk_at_[hidden]]
> >>
> > 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);
   }

-- 
Rob Stewart                           stewart_at_[hidden]
Software Engineer                     http://www.sig.com
Susquehanna International Group, LLP  using std::disclaimer;