[C++-sig] copy constructors and multiple instances

[Josh Stratton]

In my particular scene I have a Scene class, which operates as kind of
a context for my operations and holds all the meshes in the scene.  I
send my scene down to the python side so import methods will import
into the containers in the scene object.  For example,
addMeshFromFile(scene, fileName) which puts the data from the file
into the scene object.  However, if the scene object isn't be
returned, it seems I'm just copying the scene object (which might be
memory expensive), adding the data to the copy, and throwing the copy
away as I don't return it and it doesn't affect my original scene
object in C++ that I passed in.  I assume this is a fairly common
problem and I need to rework my API somehow like providing a more
robust copy constructor that does a shallow copy of my data
containers.  Still, I might have to reorganize it so I'm not passing
my scene to python.  If an object is copied every time, I think that
might be memory prohibitive.  I'm including my current source from
github.

// header file handling my scene and it's data
https://github.com/strattonbrazil/Sunshine/blob/master/src/scene.h

// functions for creating the bindings to python
https://github.com/strattonbrazil/Sunshine/blob/master/src/python_bindings.cpp

// python file which reads a file and adds it to the scene
https://github.com/strattonbrazil/Sunshine/blob/master/src/objImporter.py

Do I need to change need to change my copy constructor to do a more
shallow copy?  Maybe change my internal scene objects to pointers?
Would this alleviate the memory issue?