Question

Well, I have an abstract virtual machine (“PAWN“) which is running from my code and the scripts can execute functions, those functions are registered to the script from the C code which gets executed by my C++ code.

The c++ code has to supply an array in the form of

{ "name_i_want_the_function_to_have_in_the_script" , function_in_my_cpp_code }

if the function is not in the array, it cannot be executed. (because it doesn”t “exist”)

So this brings us to this:

My functions look like this:

//Pawn Functions
#define PWNFUNC(a) static cell AMX_NATIVE_CALL a(AMX *amx, cell *params)

namespace PawnFunc
{
    PWNFUNC(GGV)
    {
        return pGameInterface->FindGameVersion();
    }
};//namespace PawnFunc

and the array with the scripting functions information is in another file, like this:

AMX_NATIVE_INFO custom_Natives[] =
{
    {   "GetGameVersion", PawnFunc::GGV   },
    {   0,0   }
};

and the question is now:

is it possible to make that array auto updated? (before/at compile time or code initialization time)

as for now I have to add each function manually. Which is sometimes annoying and more prone for errors.

I would like to change it so I could do:

//Pawn Functions
#define PWNFUNC(a,b) ...?...

namespace PawnFunc
{
    PWNFUNC(GGV,GetGameVersion)//{ "GetGameVersion", PawnFunc::GGV }, is now added to "custom_Natives" array
    {
        return pGameInterface->FindGameVersion();
    }
};//namespace PawnFunc

Is this possible at all? If yes, how could I achieve this?

maybe it is possible to loop the namespace?

Edit: here is some pseudo code: http://ideone.com/btG2lx

And also a note: I can do it at runtime, but then it has to be done at DLLMain (my program is a DLL).

Answer 1

This #define will do the job, if you use a std::vector as the storage for your script info.

(Note that the standard guarantees that you’ll still get a C-style array from &custom_Natives[0])

std::vector<AMX_NATIVE_INFO> custom_Natives;

#define PWNFUNC(NAME, FUNC) \
 struct IMPL_ ## FUNC { \
   IMPL_ ## FUNC() { \
     AMX_NATIVE_INFO entry = { NAME, PawnFunc::FUNC }; \
     custom_Natives.push_back( entry ); \
   } \
 } INSTANCE_ ## FUNC; \
 static cell AMX_NATIVE_CALL FUNC(AMX *amx, cell *params)

Now code like this will both define the function and add the script entry to custom_Natives.

PWNFUNC("GetGameVersion", GGV)
{
    return pGameInterface->FindGameVersion();
}