int GetParams(cell* params, const char *pArgs,  ... )
{
    va_list vArguments;
    va_start( vArguments, pArgs );
    unsigned long varadr;
    int paramcount;
    while( *pArgs )
    {
           if( *pArgs == 'i' )
           {
               paramcount++;
               varadr = va_arg(vArguments, unsigned long);             
               *(int*)varadr = params[paramcount];
               logprintf("paramcount: %i ivar: %i", paramcount, params[paramcount]);
           }
           else if (*pArgs == 'f')
           {
               paramcount++;
               float fvar = amx_ctof(params[paramcount]);
               *(float*)varadr = fvar;
               logprintf("paramcount: %i fvar: %f", paramcount, fvar);
           }
           else if (*pArgs == 's')
           {
                paramcount++;
                // not coded yet
           }
           ++pArgs;
	}       
}

// .....

//----------------------------------------------------------
// public OnPlayerRequestClass(playerid, classid);
samp_call_begin(c_OnPlayerRequestClass, 2)
    int playerid;
    float classid;
    GetParams(params, "if", &playerid, &classid);
    logprintf("OnPlayerRequestClass %i %f", playerid, classid);
samp_call_end