Hello,

I'm pretty new to luabind. I'm having a little problem binding one of my string functions(convert to uppercase). Just couldn't figure it out.

[source]void STools::UCase(char *txt)
{
for (;;)
{
u_int32 t = *reinterpret_cast(txt);
...
txt++;
}
}
[/source]

Here's the luabind code
[source]luabind::module(myLuaState) [
luabind::def("convert_upper", STools::UCase)
]; [/source]

Compiler Error

[source]error C2664: 'void (char *)' : cannot convert parameter 1 from 'const char *' to 'char *' [/source]

Any help is appreciated!

http://www.rasterbar.com/products/luabind/docs.html#out-value

That explains how your C++ functions can't take non-const ref/pointers if you want to bind them to Lua. So, the out_value function policy will add a return value in Lua code, rather than modifying the input.

Where your C++ code would look like

char* str = "hi";
UCase(str);
std::cout << str; //prints 'HI'

Your Lua code would look like

local str = "hi"
local ucstr = UCase(str)
--// or you can have str = UCase(str)
print(ucstr) //prints 'HI'

Thanks a lot Gambini,

I've tried your suggestion but I'm still getting compiler errors. Any other suggestions?

out_value(_1) causes the following error:

[SOURCE] error C2352: 'luabind::native_converter_base<T>::match' : illegal call of non-static member function[/SOURCE]

out_value(_2) causes the following:

[SOURCE]error C2664: 'void (char *)' : cannot convert parameter 1 from 'const char *' to 'char *'[/SOURCE]

It looks like out_value doesn't work well with MSVC (here).

You'll have to either re-think the function or use Lua's "string.upper" function.

Another option is to make your own string class with UCase as a member function. That would bind perfectly fine to Lua, since UCase wouldn't need to take any parameters and only modify the object data.