Problem to derive a base class in C++ or in Lua

Hello Everyone

I'm writing to you because i've just tryied to use LuaBind, and i get a few basic things working : binding a function, binding a basic class. But i can't derive a class. To be more precise I can't derive in Lua a class defined in C++ ; and I can't even derive in Lua a class defined also in Lua. My C++ and Lua code is below

 

As I'm a complete beginner with LuaBind, I suppose my mistake is obvious, but I don't see it.

 

I'm using MSVC++ 9.0 on windows Vista. I've put in my project folder the lua and luabind include file. I've also put luabind source file. I link with lua51.dll.

 

Thanks in advance for your help

 

my C++ code is :

 

extern "C" {

#include "lua.h"

#include "lualib.h"

#include "lauxlib.h"

}

#include "luabind/luabind.hpp"

#include <iostream>

using namespace luabind;

using namespace std;

int main() {

lua_State *myLuaState = lua_open();

luaL_openlibs(myLuaState);

open(myLuaState);

int retLua = luaL_dofile(myLuaState,".\\Test.lua");

if (retLua !=0) {

cout << "erreur dans l'éxécution LUA :"<< retLua << endl;

}

lua_close(myLuaState);

return 0;

}

 

my Lua code is :

 

class 'lua_testclass'

function lua_testclass:__init(name)

self.name = name

end

function lua_testclass:print()

print(self.name)

end

a = lua_testclass('example')

a:print()

　

class 'derived' (lua_testclass)

function derived:__init() super('derived name')

end

function derived:print()

print('Derived:print() -> ')

lua_testclass.print(self)

end

b = derived('derived example')

b:print()

 

In this code, if b is a lua_testclass, there is no error.

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[James Porter-2]

francois.chenebit@... wrote:
> As I'm a complete beginner with LuaBind, I suppose my mistake is
> obvious, but I don't see it.
[snip]
> In this code, if b is a lua_testclass, there is no error.

The __init function for derived doesn't take any arguments, so that's
the first thing I'd fix.

- Jim


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Hello Jim

Thank you for answering me, but it wasn't that. If I change my lua code to this :

 

function derived:__init(name) super(name)
end

 

It's still doesn't work

 

By the way, I've just copied the example in the site.

 

Does someone has another idea

 

Thanks in advance.

 

François

> Message du 08/08/09 19:48

> De : "James Porter"
> A : luabind-user@...
> Copie à :
> Objet : Re: [luabind] Problem to derive a base class in C++ or in Lua
>
>
> francois.chenebit@... wrote:
> > As I'm a complete beginner with LuaBind, I suppose my mistake is
> > obvious, but I don't see it.
> [snip]
> > In this code, if b is a lua_testclass, there is no error.
>
> The __init function for derived doesn't take any arguments, so that's
> the first thing I'd fix.
>
> - Jim
>
>
> ------------------------------------------------------------------------------
> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
> trial. Simplify your report design, integration and deployment - and focus on
> what you do best, core application coding. Discover what's new with
> Crystal Reports now. http://p.sf.net/sfu/bobj-july
> _______________________________________________
> luabind-user mailing list
> luabind-user@...
> https://lists.sourceforge.net/lists/listinfo/luabind-user
>
>

Hello again

 

I've tryied another time with a different lua code :

 

function derived:__init(name)
 --super(name)
 print 'derived init'
 self.name = name
end

 

This code works. But if I uncomment the call to super, it doesn't. I've called super first as said in documentation. With this in mind, I've tryied another search on google for that problem. I've found a post by Daniel Wallin explaining that super has been deprecated. So with calling in my C++ code

luabind::disable_super_deprecation();

 

My code works.

 

I've read the documentation that is in the source, and it has another version than the one on the web site. I'll try that tomorrow to check that, but I'm confident.

 

May be it could be wise to update documentation on web site. 

 

Thanks again for your help

 

François

> Message du 08/08/09 20:13
> De : "francois.chenebit@..."
> A : luabind-user@...
> Copie à :
> Objet : Re: [luabind] Problem to derive a base class in C++ or in Lua
>
>

Hello Jim

Thank you for answering me, but it wasn't that. If I change my lua code to this :

 

function derived:__init(name) super(name)
end

 

It's still doesn't work

 

By the way, I've just copied the example in the site.

 

Does someone has another idea

 

Thanks in advance.

 

François

> Message du 08/08/09 19:48

> De : "James Porter"
> A : luabind-user@...
> Copie à :
> Objet : Re: [luabind] Problem to derive a base class in C++ or in Lua
>
>
> francois.chenebit@... wrote:
> > As I'm a complete beginner with LuaBind, I suppose my mistake is
> > obvious, but I don't see it.
> [snip]
> > In this code, if b is a lua_testclass, there is no error.
>
> The __init function for derived doesn't take any arguments, so that's
> the first thing I'd fix.
>
> - Jim
>
>
> ------------------------------------------------------------------------------
> Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day
> trial. Simplify your report design, integration and deployment - and focus on
> what you do best, core application coding. Discover what's new with
> Crystal Reports now. http://p.sf.net/sfu/bobj-july
> _______________________________________________
> luabind-user mailing list
> luabind-user@...
> https://lists.sourceforge.net/lists/listinfo/luabind-user
>
>

>
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[Colm Sloan]

The Lua wiki gives nice examples of how to create derived classes in
the "Metatables - Classes" section:
http://lua-users.org/wiki/SampleCode

e.g. Yet Another Class Implementation:
http://lua-users.org/wiki/YetAnotherClassImplementation

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