Re: [luabind] passing a pointer to an array

[Arvid N. <c9...@cs...>]

On Dec 31, 2005, at 01:26, Andrew Davis wrote:

> Thanks for the response.  I was thinking of doing the accessor to  
> get each individual particle.  I thought that might be kind of  
> innefficient, but it will work, so I will do it  that way!  Thanks  
> again.

I think letting lua run each particle individually in the first place  
may be the biggest bottleneck. However, what you want to do is  
possible if you combine a thin wrapper with the return_stl_iterator  
policy [1]. Something like this (from the top of my head) could work:

struct container_interface
{
   typedef particle value_type;
   typedef particle* iterator;

   container_interface(iterator*& p, int& s): ptr(p), size(s) {}

   iterator begin() { return ptr; }
   iterator end() { return ptr + size; }

   iterator*& ptr;
   int& size;
};

struct particle_system
{
   particle_system()
     : m_interface(m_particles, m_num_particles)
   {
     // ..
   }
   particle* m_particles;
   int m_num_particles;
   container_interface m_interface;

};

class_<particle_system>
   .def_readwrite("particles", &particle_system::m_interface,  
return_stl_iterator)

then the attribute "particles" will return a generator that can be  
used in lua's for statements.

container_interface is supposed to implement the ContainerConcept  
[2], but these members may be enough for the return_stl_interface  
policy.

--
Arvid Norberg

[1]: http://www.rasterbar.com/products/luabind/docs.html#return-stl- 
iterator
[2]: http://www.sgi.com/tech/stl/Container.html