- 1. Development Tools
- 1.1 Introduction
- 1.2 Programming with Lua and or C
- 1.3 Working with Premake
- 1.4 Bmake
- 1.5 Debugging
- 1.6 Using Fossil (DVCS)
- 1.7 Further Reading
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Using C Library's in Pure Lua (Simple)
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local ffi = require("ffi")
ffi.cdef[[
int printf(const char *fmt, ...);
]]
ffi.C.printf("Hello %s!", "world")
Using C Library's in Pure Lua (Advanced)
The following code shows how to access the zlib compression library from Lua code.
local ffi = require("ffi")
ffi.cdef[[
unsigned long compressBound(unsigned long sourceLen);
int compress2(uint8_t *dest, unsigned long *destLen,
const uint8_t *source, unsigned long sourceLen, int level);
int uncompress(uint8_t *dest, unsigned long *destLen,
const uint8_t *source, unsigned long sourceLen);
]]
local zlib = ffi.load(ffi.os == "Windows" and "zlib1" or "z")
C++ and Lua Hybrid Application
The following example uses LuaWrapper and Luajit.
LuaWrapper is a library designed to help bridge the gab between Lua and C++.
It is designed to be small (a single header file), simple, fast, and typesafe.
It has no external dependencies other than the lua library itself, and does not
need to be precompiled; the header can simply be dropped into a project and
used immediately. It even supports class inheritance to a certain degree.
Objects can be created in either Lua or C++, and passed back and forth.
The nice thing about LuaWrapper is that we can develop our C++ and Lua
frameworks side by side and still keep them separate.
main.cpp
#include <iostream>
extern "C"
{
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
#include "luajit.h"
}
#include "LuaBankAccount.hpp"
using namespace std;
int main(int argc, const char *argv[])
{
if (argc == 2)
{
lua_State* L = luaL_newstate();
luaJIT_setmode(L, -1, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_ON);
luaL_openlibs(L);
luaopen_BankAccount(L);
if (luaL_dofile(L, argv1))
cout << lua_tostring(L, -1) << endl;
lua_close(L);
}
return 0;
}
BankAccount.cpp
#include <BankAccount.hpp>
float BankAccount::s_totalMoneyInBank = 0;
BankAccount::BankAccount(const char* owner, float balance)
: m_owner(owner)
, m_balance(balance)
{
s_totalMoneyInBank += balance;
}
const char* BankAccount::getOwnerName() const
{
return m_owner;
}
void BankAccount::deposit(float amount)
{
s_totalMoneyInBank += amount;
m_balance += amount;
}
void BankAccount::withdraw(float amount)
{
s_totalMoneyInBank -= amount;
m_balance -= amount;
}
float BankAccount::checkBalance() const
{
return m_balance;
}
float BankAccount::checkTotalMoneyInBank()
{
return s_totalMoneyInBank;
}
BankAccount.hpp
#ifndef EXAMPLE_HPP_
#define EXAMPLE_HPP_
#include <string>
#include <iostream>
class BankAccount
{
public:
BankAccount(const char* owner, float balance);
const char* getOwnerName() const;
void deposit(float amount);
void withdraw(float amount);
float checkBalance() const;
static float checkTotalMoneyInBank();
private:
const char* m_owner;
float m_balance;
static float s_totalMoneyInBank;
};
#endif // EXAMPLE_HPP_
LuaBankAccount.cpp
#include <iostream>
#include <string>
extern "C"
{
#include "lua.h"
#include "lauxlib.h"
}
#include "luawrapper.hpp"
#include "BankAccount.hpp"
using namespace std;
//
// Allocator
//
// Types that do not have a default contructor require you to write an allocator function.
// This function is passed to luaW_register.
//
BankAccount* BankAccount_new(lua_State *L)
{
const char* owner = luaL_checkstring(L, 1);
float balance = luaL_checknumber(L, 2);
return new BankAccount(owner, balance);
}
//
// Static Functions
//
// These functions can be called directly from the BankAccount table in lua
//
int BankAccount_checkTotalMoneyInBank(lua_State *L)
{
lua_pushnumber(L, BankAccount::checkTotalMoneyInBank());
return 1;
}
//
// Member Functions
//
// These functions are stored on the BankAccount.metatable table.
// All BankAccount objects in Lua have access to the functions defined there
// by the use of special a __index metatmethod that is set up by LuaWrapper.
//
int BankAccount_getOwnerName(lua_State *L)
{
BankAccount* account = luaW_check(L, 1);
lua_pushstring(L, account->getOwnerName());
return 1;
}
int BankAccount_deposit(lua_State *L)
{
BankAccount* account = luaW_check(L, 1);
float amount = luaL_checknumber(L, 2);
account->deposit(amount);
return 0;
}
int BankAccount_withdraw(lua_State *L)
{
BankAccount* account = luaW_check(L, 1);
float amount = luaL_checknumber(L, 2);
account->withdraw(amount);
return 0;
}
int BankAccount_checkBalance(lua_State *L)
{
BankAccount* account = luaW_check(L, 1);
lua_pushnumber(L, account->checkBalance());
return 1;
}
static luaL_Reg BankAccount_table[] =
{
{ "checkTotalMoneyInBank", BankAccount_checkTotalMoneyInBank },
{ NULL, NULL }
};
static luaL_Reg BankAccount_metatable[] =
{
{ "getOwnerName", BankAccount_getOwnerName },
{ "deposit", BankAccount_deposit },
{ "withdraw", BankAccount_withdraw },
{ "checkBalance", BankAccount_checkBalance },
{ NULL, NULL }
};
int luaopen_BankAccount(lua_State* L)
{
luaW_register(L,
"BankAccount",
BankAccount_table,
BankAccount_metatable,
BankAccount_new // If your class has a default constructor you can omit this argument,
// LuaWrapper will generate a default allocator for you.
);
return 1;
}
LuaBankAccount.hpp
#ifndef LUAEXAMPLE_HPP_
#define LUAEXAMPLE_HPP_
struct lua_State;
int luaopen_BankAccount(lua_State*);
#endif // LUAEXAMPLE_HPP_
example1.lua
alicesaccount = BankAccount.new("Alice", 100)
alicesaccount:deposit(20);
alicesaccount:deposit(30);
alicesaccount:deposit(40);
bobsaccount = BankAccount.new("Bob", 200)
bobsaccount:withdraw(10);
bobsaccount:withdraw(15);
bobsaccount:withdraw(20);
function printaccountbalance(account)
local name = account:getOwnerName()
local balance = account:checkBalance()
print(string.format("%s has $%d", name, balance))
end
printaccountbalance(alicesaccount)
printaccountbalance(bobsaccount)
print(string.format("The bank has $%d", BankAccount.checkTotalMoneyInBank()))
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