How to embed Lua 5.1 in C + +

http://blog.csdn.net/cnjet/article/details/5909555

Lua, is a scripting language providing dynamic Data structures, maths, IO and string manipulations just as any interpret E language such as Bash, Python, Ruby etc.

What's so special about Lua?
Lua is Fast, Light-weight and embeddable.

Lua can is embedded into C and C + + programs and Lua core is statically complied with your C + + programs, meaning your C + + Program itself is now becoming LUA interpreter that execute LUA scripts. To extend your C + + application to execute Lua script was simple, lets check it out.

Before you start, please download and install Lua from here.
Disclaimer:my example is based on Lua 5.1.3.

1. Create a simple Lua script and name it as Foo.lua.

io.write("Please enter your name: ")name = io.read() -- read input from userprint ("Hi " .. name .. ", enjoy hacking with Lua");

2. Write a CPP program Clua.cpp to execute Foo.lua.

01	extern"C"{

02	#include "lua.h"

03	#include "lualib.h"

04	#include "lauxlib.h"

05

}

06

07

intmain()

08

{

09

ints=0;

10

11	lua_State *L = lua_open();

12

13	// load the libs

14	luaL_openlibs(L);

15

16	//run a Lua scrip here

17	luaL_dofile(L,"foo.lua");

18

19	printf("/nI am done with Lua in C++./n");

20

21	lua_close(L);

22

23

return0;

24

}

The Lua API is in c format, and in the order to do it work with C + + need to extern "C". Lual_openlibs (L) loading up all the basic libs such as IO, String, Math etc. I believe if you is using Lua 5.0, you have to replace Lual_open (L) to load the libs one by one

      luaopen_base(L);      luaopen_table(L);      luaopen_io(L);      luaopen_string(L);      luaopen_math(L);

3. Compile the clua.cpp with g++.

g++ -o clua{,.cpp} -llua -ldl

important! You need to link your program with LIBDL besides Liblua. I believe the use of lual_openlibs () is calling Dlopen, Dlclose, Dlerror, dlsym which needs LIBDL.

Else you could get linking error like this:

/usr/local/lib/liblua.a(loadlib.o): In function `ll_loadfunc‘:loadlib.c:(.text+0x917): undefined reference to `dlsym‘loadlib.c:(.text+0x924): undefined reference to `dlerror‘loadlib.c:(.text+0x9fc): undefined reference to `dlopen‘loadlib.c:(.text+0xa11): undefined reference to `dlerror‘/usr/local/lib/liblua.a(loadlib.o): In function `gctm‘:loadlib.c:(.text+0x101e): undefined reference to `dlclose‘collect2: ld returned 1 exit status

4. Execute your C + + app

$ ./cluaPlease enter your name: surfaceHi surface, enjoy hacking with LuaI am done with Lua in C++.

Cool isn ' t it?

Lets try to change Foo.lua into this:

io.write("Please enter your name: ")name = io.read()io.write("Hi " .. string.format("/27/91/1;38;40m%s/27/91/0;47;40m",name) .. ", enjoy hacking with Lua/n");

Now, run ./clua again! You name'll is in RED, check out the text color example here

Ofcause, in order to really extend your C + + apps to Lua script, you need more than Lua_dofile (), you need to allow Lua SCR IPT calling your C + + functions, you may need to access variables from Lua to C + + and vice versa. Well, mean while I am still learning, I'll share more if I learn more tricks!

Reference and tutorial!
Lua provides excellent documentation:

• 1. Lua Reference Manual
• 2. Ebook:programming in Lua

I am dilemma here whether should I post this at http://linux.byexamples.com orhttp://cc.byexamples.com. As an introduction post for Lua programming, I'll put it on both blogs. For the post, if I write about Lua scripting, I'll post at http://linux.byexamples.com and if I write about Lua C + + A PI, it'll be at http://cc.byexamples.com.

Hope you enjoy this post, and start to script with Lua.
@lightstar: In the case of you is reading this, I would like to say thank-introduce this wonderful language to me, I Enj Oy it very much!

How to embed Lua 5.1 in C + +