How to bind a C++ class to Lua?

Lunar wraps this common pattern:

#include "lunar.h"
class Account {
 lua_Number m_balance;
public:
 static const char className[];
 static Lunar<Account>::RegType methods[];
 Account(lua_State *L) { m_balance = luaL_checknumber(L, 1); }
 int deposit (lua_State *L) { m_balance += luaL_checknumber(L, 1); return 0; }
 int withdraw(lua_State *L) { m_balance -= luaL_checknumber(L, 1); return 0; }
 int balance (lua_State *L) { lua_pushnumber(L, m_balance); return 1; }
 ~Account() { printf("deleted Account (%p)\n", this); }
};
const char Account::className[] = "Account";
Lunar<Account>::RegType Account::methods[] = {
 LUNAR_DECLARE_METHOD(Account, deposit),
 LUNAR_DECLARE_METHOD(Account, withdraw),
 LUNAR_DECLARE_METHOD(Account, balance),
 {0,0}
};
....
Lunar<Account>::Register(L);

This does all the userdata and metatable creation for you; each method of your class iwill be a normal Lua C function that gets its arguments from the stack as usual.

tolua++ is an attractive solution because it can parse 'cleaned' C/C++ headers and generate the bindings.

A very simple example: say we have a burning need for the C function strstr; given this file lib.pkg:

const char *strstr(const char*, const char*);

then tolua -o lib.c lib.pkg will generate a binding file lib.c which can be compiled and linked against the tolua library.

require 'lib' may result in a surprise, since there is no table lib generated, only a global function strstr. To put the function into a tble lib, lib.pkg must look like this:

module lib
{
 const char *strstr(const char*, const char*);
}

So .pkg files are not really C/C++ headers; however, it is not difficult to convert headers into .pkg files by cleaning them up.

An alternative to tolua is luabind

SWIG is a popular binding generator which can target Lua as well. If a SWIG binding exists for a library, then it is relatively easy to generate Lua bindings from it.

How to bind a C++ class to Lua?

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