Multi tool use

What is wrong with my SWIG typemap?

I created a SWIG typemap for my function.

%typemap(in) (int width, int height, lua_State *L)
{
if (!lua_isnumber(L, -1) || !lua_isnumber(L, -2))
SWIG_exception(SWIG_RuntimeError, "argument mismatch: number expected");
$1 = lua_tonumber(L, -1);
$2 = lua_tonumber(L, -2);
$3 = L;
}


But it doesn't work if I try to call the function in Lua.

I call this function like the following in Lua.

createWindow(500,300)

createWindow(500,300)

I just want to pass width, height from Lua to this function.

width

height

How can I fix the typemap to make it work?

lua_State*

lua_State*

void createWindow(int width, int height)

1 Answer
1

Multi-argument typemaps won't do the trick here because they are designed to map a single Lua argument to multiple C++ arguments. You can help yourself with a default argument here. This is done using %typemap(default). We tell SWIG to default any lua_State *L argument to the instance used by SWIG.

%typemap(default)

lua_State *L

%module window

%{
#include <iostream>

void createWindow(int width, int height, lua_State *L) {
std::cout << "Creating window of size " << width << "x" << height << 'n'
<< "Number of arguments: " << lua_gettop(L) << 'n';
}
%}

%typemap(default) (lua_State *L) {
$1 = L;
}

void createWindow(int width, int height, lua_State *L);


local window = require("window")
window.createWindow(500,300)


$ lua5.2 test.lua
Creating window of size 500x300
Number of arguments: 2


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