Embed parallel Lua states in Python

Lua is a popular embedded scripting language used by many tools and games such as World of Warcraft. There is also a Python port called Lunatic-Python. It wraps around liblua (the C library) and allows you to execute Lua code in Python and Python code in Lua.

I've created a fork of Lunatic-Python in:

https://github.com/kennu/Lunatic-Python

This fork allows you to create multiple Lua states, each of which has its own set of global variables.

Previously, in Python you would execute Lua with a global state like this:

import lua
lua.globals()['msg'] = {'hello':'world'}
lua.execute("print(msg.hello)")

Now you can create multiple independent states using the new_state() function:

import lua
s1 = lua.new_state()
s2 = lua.new_state()
s1.globals()['msg'] = {'hello':'world'}
s2.globals()['msg'] = {'hello':'foobar'}
s1.execute("print(msg.hello)")
s2.execute("print(msg.hello)")

The purpose of this is that you can safely create a new, clean state when you're executing Lua in a Python function, and you don't have to worry about the global state overlapping with some other function or thread.

Please consider this fork experimental for now. It passes the test_lua.py tests but it may still contain memory leaks or other problems. Also, I have not tested it for embedding Python into Lua at all.