[luabind] shared_ptr and nil

[Jean-Claude M. <jc_...@em...>]

Hello,

When I export a class using shared_ptr, my lua script can crash the
application if it calls a method of object that is "NULL". Here is some
test code to illustrate that crash:

Class to export:
	class TestClass {
		double val;
	public:
		boost::shared_ptr<TestClass> FindNode( const std::string &nodeName )
		{
			// always return NULL for that test, in the real class it only returns NULL if it couldn't find the node.
			return boost::shared_ptr<TestClass>();
		}
		void DoSomething( double v )
		{
			val = v;
		}
	};

luabind export:
	luabind::module(m_luaState) [
		luabind::class_<TestClass, boost::shared_ptr<TestClass>>("TestClass")
			.def(luabind::constructor<>())
			.def("FindNode", &TestClass::FindNode)
			.def("DoSomething", &TestClass::DoSomething)
	];


lua script:
	test = TestClass()
	test:DoSomething(0.0)
	node = test:FindNode("test")
	node:DoSomething(0.0)

When I call this small test script, the variable node is an emptry(NULL)
shared_ptr. When the script calls the DoSomething method, it extecutes
the DoSomething with the "this" pointer at adress 0, therefore the
application crashes.
It souldn't be possible to crash the application from an external
script. If I export the class with raw pointers (see example below), the
script aborts with the following message:
"script.lua:4: attempt to index global 'node' (a nil value)"
This is the behaviour I would like to have (abort script instead of
application crash).
However, I need shared_ptr. Is it possible get the same behaviour with
shared_ptr? Did I do something wrong in my luabind usage? I'm new to
luabind.


Same class, but with raw pointers (abort instead of application crash
with the same script):

	class TestClass {
		double val;
	public:
		TestClass* FindNode( const std::string &nodeName )
		{
			return NULL;
		}
		void DoSomething( double v )
		{
			val = v;
		}
	};

	luabind::module(m_luaState) [
		luabind::class_<TestClass>("TestClass")
			.def(luabind::constructor<>())
			.def("FindNode", &TestClass::FindNode)
			.def("DoSomething", &TestClass::DoSomething)
	];
-- 
  Jean-Claude Monnin
  jc_...@em...