Re: [Lua-icxx-users] lua_icxx + swig

[Domenico M. <dm...@gm...>]

After looking carefully at the source code, I found that you make use
of pushValToStack.


This can be used for a custom stack allocation to handle the swig call.

Here is what I've done :

I restored the original lua_icxx source code and added to LuaObjRef.h  the
following code


struct LUA_ICXX_CPP_API
UserStackAllocation
{
     virtual void pushToStack(lua_State* L) const = 0;
};

void pushValToStack(lua_State* L, const UserStackAllocation& objRef)
{
    objRef.pushToStack(L);
}




In my code I derive from UserStackAllocation to handle the swig calls

class Swig : public UserStackAllocation
{
     Swig(Foo* f);

     void pushToStack(lua_State* L) const {
                    SWIG_Lua_NewPointerObj( L, .... );
          }
}



Now I can simply use the standard way of calling a function


    void execCallback()
     {
       cb( Swig( new Foo ) );
     }


This solution is cleaner
Let me know if you are interested in adding it to the project

Thanks

Dom

On Sun, Feb 5, 2012 at 7:12 PM, Domenico Mangieri <dm...@gm...> wrote:

> I doesn't work as it is so I modified slightly lua_icxx code to
> accommodate this requirement.
>
> This is just a quick solution..
>
> with the changed code I can do this
>
>
>     void execCallback()
>      {
>        LuaFuncCallParams call= cb.prepCall()   // this is now public
>
>        SWIG_Lua_NewPointerObj( L, new Foo() .... )  // push wrapped object
> on the stack
>
>        call.doCall(1);   // doCall gets extra number of params pushed on
> the stack
>      }
>
>
>         This works.
>
>         Maybe it can be implemented differently but I'm sure this could be
> a popular feature for lua_icxx as I think the combo swig + lua_icxx is a
> winner!
>
>
>    Dom
>
>
>
> On Sun, Feb 5, 2012 at 5:26 PM, Domenico Mangieri <dm...@gm...>wrote:
>
>> Hi ..  more on this..
>>
>> I found that I can use  SWIG_Lua_NewPointerObj  provided by swig
>> generate file  to create the wrapping object
>>
>>
>>     void execCallback()
>>      {
>>        SWIG_Lua_NewPointerObj( L, new Foo() .... )
>>
>>        cb();
>>      }
>>
>> SWIG_Lua_NewPointerObj pushes the object into lua stack.
>>
>> Now the question is, can I call cb with no args given the pointer is
>> already in the stack  ?
>>
>> I'll give it a try..
>>
>> Dom
>>
>>
>>
>>
>> On Sun, Feb 5, 2012 at 3:34 PM, Domenico Mangieri <dm...@gm...>wrote:
>>
>>> Hi,
>>>
>>> I'm playing around with lua_icxx. I find it very useful with its unique
>>> approach to lua calls within c++.
>>>
>>> I'm currently using swig to wrap a large library and I'm using lua_icxx
>>> to provide callback supports from within c++ into lua.
>>>
>>> Here is an example
>>>
>>> *c++ *
>>>
>>> // Note : Foo is wrapped by swig
>>>
>>> class Foo
>>> {
>>>   public:
>>>
>>>     LuaFuncRef cb;
>>>
>>>     void registerCallback(const char* cb)
>>>     {
>>>         cb = _lua.eval(cb);
>>>     }
>>>     .....
>>>
>>>     void execCallback()
>>>     {
>>>        cb();
>>>     }
>>> };
>>>
>>>
>>>
>>>
>>>
>>> *lua :*
>>>
>>>
>>> function test()
>>>     print("cool")
>>> end
>>>
>>> f = Foo()
>>> f:registerCallback("test");
>>>
>>>
>>>
>>>
>>> That's all good.
>>>
>>> My problem now is to make use of swig wrap to pass c++ objects to lua
>>> callback;
>>>
>>> Something like this
>>>
>>>     void execCallback()
>>>     {
>>>        cb( new Foo );
>>>     }
>>>
>>> The callback works fine with basic types but not for UDT.
>>>
>>> Any idead how that could be solved ?
>>>
>>>
>>> Thank you for sharing this lib.
>>>
>>> Dom
>>>
>>>
>>
>