This repository is still work in progress but starts to be useable. You can find classes to use Lua's API in C++ and use it to script things into your C++ programs.
This has been tested with C++ 20 on g++, Lua 5.4 and Ubuntu 22.04.
Clone this repository and compile the static or shared library (see this) like this:
make libluaincpp.a
make libluaincpp.soThen you're free to use and link it with your program.
Here is a a Lua file and a C++ file showing you some of the features that this library does, you can find these files in the example folder:
function greets(name)
print("[Lua] Hello "..name)
end
function my_sin_int(x)
print("[Lua] "..math.sin(x))
end
function is_true(b)
print("[Lua] ", b == true)
end
function my_sin_float(x)
print("[Lua] "..math.sin(x))
end
function both_sin(x1, x2)
my_sin_float(x1)
my_sin_int(x2)
end
function all(name, b, f, i)
greets(name)
is_true(b)
my_sin_float(f)
my_sin_int(i)
return 1234
end
function add_test()
print("[Lua] "..mymath.add(1, 2))
end
#include <string.h>
#include "LuaInCpp.hpp"
// To call a C++ function in Lua, you have to use the Lua API
// Here's an example:
int add(lua_State *l)
{
int n = lua_gettop(l); // get the number of arguments
if (n != 2) {
lua_pushliteral(l, "bad number of arguments");
lua_error(l);
}
int a = lua_tointeger(l, 1); // get first argument
int b = lua_tointeger(l, 2); // get second arument
std::cout << "[C++] " << a << " + " << b << std::endl;
lua_pushinteger(l, a + b); // the return value
return 1; // number of argument returned
}
int main()
{
Lua l;
l.openLibs();
l.add("add", &add, "mymath");
if (l.loadFile("test.lua")) {
LuaFunction<void(const char *)> greets(l, "greets");
char *s = strdup("Frodo"); // works with not const too
greets(s);
LuaFunction<void(int)> my_sin(l, "my_sin_int");
long a = 0; // works with long too
my_sin(a);
LuaFunction<void(double)> my_sin_float(l, "my_sin_float");
my_sin_float(2.3);
LuaFunction<void(bool)> is_true(l, "is_true");
is_true(false);
LuaFunction<void(double, int)> both_sin(l, "both_sin");
both_sin(2.3, 4);
std::cout << std::endl;
LuaFunction<int(const char *, bool, double, int)> all(l, "all");
int b = all(s, false, 2.3, 4);
std::cout << b << std::endl;
l.call("main");
}
}Compile and run like this:
make test
./testAnd the output will be:
[Lua] Hello Frodo
[Lua] 0.0
[Lua] 0.74570521217672
[Lua] false
[Lua] 0.74570521217672
[Lua] -0.75680249530793
[Lua] Hello Frodo
[Lua] false
[Lua] 0.74570521217672
[Lua] -0.75680249530793
1234
[C++] 1 + 2
[Lua] 3
This library is able to do:
- Injecting C++ values, functions and tables in a lua instance
- Call thoses C++ functions in lua
- Call lua functions in C++ (cannot call functions with multiple return values for now)
To compile this project into a shared library, you must also have a shared library of lua itself. For that, you can go here to download the source code of your favorite version of lua and tweak the Makefile in the src folder to create a liblua.so and place it next to the liblua.a already installed on your system
Then you can have this library in a shared format like that:
make libluaincpp.soIf you have any idea on how to solve these problems or you want to contribute, please open an issue, I'll be happy to discuss it with you
- Can't call lua functions with multiple return values
- The library isn't installed on the machine for now, I believe it's only a few Makefile changes and it would be okay
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