pocketpy/docs/bindings_lua.md

icon	title	order
cpu	Reuse Lua Bindings	17

pkpy provides a lua bridge to reuse lua bindings. It allows you to run lua code and call lua functions in python.

Add lua_bridge.hpp and lua_bridge.cpp in 3rd/lua_bridge to your project. Make sure lua.h, lualib.h and lauxlib.h are in your include path because lua_bridge.hpp needs them.

The lua bridge is based on lua 5.1.5 for maximum compatibility. lua 5.2 or higher should also work.

Setup

Use initialize_lua_bridge(VM*, lua_State*) to initialize the lua bridge. This creates a new module lua in your python virtual machine.

You can use lua.dostring to execute lua code and get the result. And use lua.Table() to create a lua table. A lua.Table instance in python is a dict-like object which provides a bunch of magic methods to access the underlying lua table.

class Table:
    def keys(self) -> list:
        """Return a list of keys in the table."""

    def values(self) -> list:
        """Return a list of values in the table."""

    def items(self) -> list[tuple]:
        """Return a list of (key, value) pairs in the table."""

    def __len__(self) -> int:
        """Return the length of the table."""

    def __contains__(self, key) -> bool:
        """Return True if the table contains the key."""

    def __getitem__(self, key): ...
    def __setitem__(self, key, value): ...
    def __getattr__(self, key): ...
    def __setattr__(self, key, value): ...

Example

#include "lua_bridge.hpp"

using namespace pkpy;

int main(){
    VM* vm = new VM();

    // create lua state
    lua_State* L = luaL_newstate();
    luaL_openlibs(L);

    // initialize lua bridge
    initialize_lua_bridge(vm, L);

    // dostring to get _G
    vm->exec("import lua");
    vm->exec("g = lua.dostring('return _G')");

    // create a table
    vm->exec("t = lua.Table()");
    vm->exec("t.a = 1");
    vm->exec("t.b = 2");

    // call lua function
    vm->exec("g.print(t.a + t.b)");     // 3
    
    return 0;
}