rufus-lua

Lua embedded in Ruby, via Ruby FFI.

(Lua 5.1.x only, sorry).

Lua

http://www.lua.org/about.html says :

Lua is a powerful, fast, lightweight, embeddable scripting language.

Lua combines simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics. Lua is dynamically typed, runs by interpreting bytecode for a register-based virtual machine, and has automatic memory management with incremental garbage collection, making it ideal for configuration, scripting, and rapid prototyping.

http://www.lua.org/

other Ruby and Lua bridges / connectors

https://github.com/glejeune/ruby-lua by Gregoire Lejeune
http://rubyluabridge.rubyforge.org/ by Evan Wies
https://github.com/whitequark/rlua by Peter Zotov

getting Lua on your system

On Debian GNU/Linux, I do

sudo apt-get install liblua5.1-0

If your system’s package manager doesn’t have some version (5.1.x) of Lua around, jump to compiling liblua.dylib below.

Rufus-lua will look for library in a list of know places.

If it doesn’t find the Lua dynamic library or if it picks the wrong one, it’s OK to set the LUA_LIB environment variable. For example:

bash LUA_LIB=~/mystuff/lualib.5.1.4.so ruby myluacode.rb or bash export LUA_LIB=~/mystuff/lualib.5.1.4.so # ... ruby myluacode.rb

using rufus-lua

gem install rufus-lua

or add to your Gemfile:

ruby gem 'rufus-lua'

then

```ruby require ‘rufus-lua’

s = Rufus::Lua::State.new

puts s.eval(“return table.concat({ ‘hello’, ‘from’, ‘Lua’ }, ‘ ‘)”) # # => “Hello from Lua”

s.close ```

binding Ruby code as Lua functions

```ruby require ‘rufus-lua’

s = Rufus::Lua::State.new

s.function ‘key_up’ do |table| table.inject({}) do |h, (k, v)| h[k.to_s.upcase] = v end end

p s.eval(%{ local table = { CoW = 2, pigs = 3, DUCKS = ‘none’ } return key_up(table) – calling Ruby from Lua… }).to_h # => { ‘COW’ => 2.0, ‘DUCKS => ‘none’, ‘PIGS’ => 3.0 }

s.close ```

It’s OK to bind a function inside of a table (library):

```ruby require ‘rufus-lua’

s = Rufus::Lua::State.new

s.eval(“rubies = {}”) s.function ‘add’ do |x, y| x + y end

s.eval(“rubies.add(1, 2)”) # => 3.0

s.close ```

You can omit the table definition (only 1 level allowed here though):

```ruby require ‘rufus-lua’

s = Rufus::Lua::State.new

s.function ‘rubies.add’ do |x, y| x + y end

s.eval(“rubies.add(1, 2)”) # => 3.0

s.close ```

The specs contain more examples:

https://github.com/jmettraux/rufus-lua/tree/master/spec/

eval(code[, binding[, filename[, lineno ]]])

The examples so far have shown Rufus::Lua::State#eval being used with a single argument, a piece of code.

But this rufus-lua eval mimics the Ruby eval and lets one specify binding, filename and lineno.

(TODO) Binding hasn’t yet been implemented. It’ll probaby be with setfenv but nothing sure yet. Stick a nil to it for now.

The string of Lua code may come from wild places, it may help to flag it with arbitrary filename and lineno.

```ruby require ‘rufus-lua’

lua = Rufus::Lua::State.new

lua.eval(‘print(“hello”)’, nil, ‘myluastuff/hello.lua’, 77) ```

compiling liblua.dylib

original instructions by Adrian Perez at:

http://lua-users.org/lists/lua-l/2006-09/msg00894.html

get the source at:

http://www.lua.org/ftp/lua-5.1.4.tar.gz

then

tar xzvf lua-5.1.4.tar.gz cd lua-5.1.4

Modify the file src/Makefile as per http://lua-users.org/lists/lua-l/2006-09/msg00894.html

It’s mostly about adding that rule to the src/Makefile: make liblua.dylib: $(CORE_O) $(LIB_O) $(CC) -dynamiclib -o $@ $^ $(LIBS)

Here’s how to build the library file and deploy it: ``` make make macosx # or make linux … make -C src liblua.dylib sudo cp src/liblua.dylib /usr/local/lib/

sudo make macosx install ```

I tend to copy the lib with

``` sudo cp src/liblua.dylib /usr/local/lib/liblua.5.1.4.dylib

instead of

#sudo cp src/liblua.dylib /usr/local/lib/ ```

tested with

ruby 1.8.7p72, ruby 1.9.1p0, jruby 1.2.0 jruby 1.1.6 has an issue with errors raised inside of Ruby functions (callbacks)

ruby-ffi 0.4.0 and 0.5.0

I run the specs with

bundle install # first time only bundle exec rspec

dependencies

the ruby gem ‘ffi’

issue tracker

http://github.com/jmettraux/rufus-lua/issues

source

http://github.com/jmettraux/rufus-lua

git clone git://github.com/jmettraux/rufus-lua.git

authors and credits

see CREDITS.txt

license

MIT

Lua itself is licensed under the MIT license as well :

http://www.lua.org/license.html