Strange error when working with C++ Module

[Adult]

Well to start, here's the error:

Error - no MetaName string type for userdata (AGH!)

I have a userdata object is essentially a wrapper around C++'s fstream. I have everything set up all well and good but whenever I call a method of the userdata, the game crashes with this result. Note: the metatable is set up properly, however I don't exactly know how references work.

[url=https://github.com/matteisan/proio]This is the code[/url]. I aimed for it to be self-explanatory, but if I need to elaborate on anything, I can do so.

Thanks for any help, in advance.

[editline]15th July 2014[/editline]

Update: I found where the error originates.

[url=https://github.com/matteisan/proio/blob/master/src/lua_file.cpp]lua_file.cpp[/url]

proio::File* L_GetFile( lua_State *state, int inx ) {
	GarrysMod::Lua::UserData *ud = ( GarrysMod::Lua::UserData * ) LUA->GetUserdata( inx );
	return ( proio::File * ) ud->data; 
}

For some reason, ud is becoming NULL. I do not know why, as when it is pushed onto the stack it is fine.

[Fredy]

First off, you should check if the provided index contains a valid useradata using LUA->CheckType().
Can you please post the lua code you get that error from?

[Adult]

require'proio'
local f = File( 'test.txt' ) -- Whitelisted
f.Close()

Any member function to File causes this error.

I will try the CheckType right now to see if it makes a difference.

[editline]15th July 2014[/editline]

So it looks like you were right with the CheckType. It appears I am mistaken with the metamethods, I had thought it had the same semantics as Lua.

For instance:
Lua

File:Write( content ) = File.Write( File, content ) 

So in C++, does the File not get passed as the first argument? How does one access 'self' ?

[editline]15th July 2014[/editline]

Oh hell, this whole time I was doing f.Close() not f:Close(). I'm a new kind of idiot.

Thanks.