Lua embedded in Ruby, via Ruby FFI

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/

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

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.

If you don't have liblua.dylib on your system, scroll until "compiling liblua.dylib" to learn how to get it.

  gem install rufus-lua

or add to your Gemfile:

  gem 'rufus-lua'

then

  require 'rufus/lua'

  s = Rufus::Lua::State.new

  puts s.eval("return table.concat({ 'hello', 'from', 'Lua' }, ' ')")
    #
    # => "Hello from Lua"

  s.close

  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) :

  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) :

  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/

rufus-lua's rdoc is at :

http://rufus.rubyforge.org/rufus-lua/

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

make make macosx # or make linux ... make -C src liblua.dylib sudo cp src/liblua.dylib /usr/local/lib/

sudo make macosx install

The following gems are needed to run the specs

sudo gem install bacon

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

the ruby gem 'ffi'

On the rufus-ruby list :

http://groups.google.com/group/rufus-ruby

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

irc.freenode.net #ruote

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

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

many thanks to the authors of Ruby FFI, and of Lua

• http://wiki.github.com/ffi/ffi
• http://lua.org/

• John Mettraux, [email protected], http://lambda.io/jmettraux
• Alain Hoang, http://blogs.law.harvard.edu/hoanga/
• Scott Persinger, http://github.com/scottpersinger/

http://rufus.rubyforge.org

MIT

Lua itself is licensed under the MIT license as well :

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