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calling a C++ method bound from Lua with Luabind

Started by sp00n Sep 29, 2008 at 4:12 AM 1 replies 1.8k views

Original Post

Sep 29, 2008 at 4:12 AM

Hi All, I have been trying to integrate Lua into a project for the first time, using Luabind. I have a quake-style console, to which I would like to redirect Lua's print output to. the initialization code is as follows:


module(L)
[
	class_<cConsole>("Console")
		.def("print", &cConsole::Print)
		.def("get" ,&cConsole::Get)
]

m_SubSystems->AddSubsystem(100, GFX()); // init GFX by calling macro GFX(),
					// which creates GFX and inits it if
					// it does not exist already, and 					
					//returns a pointer to the GFX class.

cConsole* conptr = GFX()->m_pConsole;
luabind::globals(L)["con"] = &conptr   // assert fails here

luaL_dostring(L, "print = function(s) con:print(s) end");

The code compiles, but when I execute I get a failed assertion: Assertion Failed, luabind.../policy.hpp Line 487 Expression: crep && "you are trying to use an unregistered type" Where am I going wrong? This seems such a simple task but I feel like I have been banging my head against a brick wall! :)

Cygon

Sep 29, 2008 at 5:20 AM

You're passing a pointer to a pointer to your console in these lines:

cConsole* conptr = GFX()->m_pConsole;luabind::globals(L)["con"] = &conptr   // assert fails here

Try

cConsole &console = *GFX()->m_pConsole;luabind::globals(L)["con"] = console;

Haven't checked it out actually compiling something, but maybe one level of indirection (Console *) is okay.

If the problem persists, just report back, I'll be around ;)

sp00n

Sep 29, 2008 at 11:48 AM

Hi Cygon,

Thanks very much for the help. The code you posted has certainly helped me out. The program now compiles and executes. However, whilst shutting down, when I execute lua_close(L), the GC tries to delete the Console object, causing problems, as it has already been deleted elsewhere. (At least I know that the binding is working now!:) )

Also, my efforts to redirect Lua's print() function have failed - the line

luaL_dostring(L, "print = function(s) con:print(s) end")

executes without returning an error, but calls to print() from Lua in my main game loop do not get passed to the console. I tried calling con:print('test') instead, but this results in LuaL_dostring returning 0, so something is not working properly there.

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