Re: Creating SWIG Lua objects from within C++

[Michael Wyman <michael@...>]

To clarify, the type name is usually something like "MyClassName *", and is something Swig generates in the _wrap.cxx file.

And the result of this method is your object (in the SWIG-wrapped type) on top of the Lua stack.

-Michael


On Apr 14, 2011, at 4:25 PM, Michael Wyman wrote:

> You'll want to look at SWIG_TypeQuery and SWIG_NewPointerObj(). You should have SWIG generate a header for you to include in your code, which is where SWIG_TypeQuery and SWIG_NewPointerObj will be defined. You can get that by running "swig -lua -external-runtime -o SwigRuntime.h". Include SwigRuntime.h in any code you have that needs to interact with the Swig-generated code.
> 
> To expose objects from C++, I've usually had a method doing the following:
> 
> bool LuaPushObject( const char* typeName, void* obj, bool own )
> {   
>    swig_type_info* typeinfo = SWIG_TypeQuery( m_L, typeName );
>    if ( typeinfo != NULL )
>    {   
>        SWIG_NewPointerObj( m_L, obj, typeinfo, (own ? 1 : 0) );
>        return true;
>    }   
>    return false;
> }
> 
> I hope that helps...
> 
> -Michael Wyman
> 
> 
> On Apr 14, 2011, at 3:37 PM, Lucas Zawacki wrote:
> 
>> Hello all. I've recently used SWIG to successfully bind a lot of C++
>> classes to be used from inside some lua scripts. However I want to be
>> able to create some of these objects in the C++ side and then expose
>> them to the Lua scripts and that's proving to be quite hard.
>> 
>> The SWIG function "_wrap_new_Class()" seems to create a new object of
>> type Class and leave it on top of the stack so it looks like the way
>> to go, but I'm getting an undefined reference to it. I tried to issue
>> a prototype like "extern _wrap_new_Class(lua_State* L);" in the file
>> using it but it doesn't seem to have any effect.
>> 
>> The compile line I'm using is more or like "g++ main.cpp
>> file_using_cpp_obj.o all_the_bound_classes.a -llua -ldl".
>> 
>> Thanks for your time
>> 
>