lupa 0.4

Simple wrapper around LuaJIT

Lupa

Lupa integrates the LuaJIT2 runtime into CPython. It is a partial rewrite of LunaticPython in Cython. Note that it is currently lacking some features and a lot of testing compared to LunaticPython, so it does yet make for a production-ready Lua integration.

Examples

>>> from lupa import LuaRuntime
>>> lua = LuaRuntime()

>>> lua.eval('1+1')
2

>>> lua_func = lua.eval('function(f, n) return f(n) end')

>>> def py_add1(n): return n+1
>>> lua_func(py_add1, 2)
3

Advantages over LunaticPython

• separate Lua runtime states through a LuaRuntime class

• frees the GIL and supports threading in separate runtimes when calling into Lua

• supports Python 2.x and 3.x, potentially starting with Python 2.3 (currently untested)

• written for LuaJIT2, as opposed to the Lua interpreter (tested with LuaJIT 2.0.0-beta4)

• much easier to hack on and extend as it is written in Cython, not C

Why use it?

It complements Python very well. Lua is a language as dynamic as Python, but LuaJIT compiles it to very fast machine code, sometimes faster than many other compiled languages. The language runtime is extremely small and carefully designed for embedding. The complete binary module of Lupa, including a statically linked LuaJIT2 runtime, is only some 400KB on a 64 bit machine.

However, Lua code is harder to write than Python code as the language lacks most of the batteries that Python includes. Writing large programs in Lua is rather futile, but it provides a perfect backup language when raw speed is more important than simplicity.

Lupa is a very fast and thin wrapper around LuaJIT. It makes it easy to write dynamic Lua code that accompanies dynamic Python code by switching between the two languages at runtime, based on the tradeoff between simplicity and speed.

Installing lupa

1. Download and unpack lupa

   http://pypi.python.org/pypi/lupa

2. Download LuaJIT2

   http://luajit.org/download.html

3. Unpack the archive into the lupa base directory, e.g.:

   .../lupa-0.1/LuaJIT-2.0.0-beta4

4. Build LuaJIT:

   cd LuaJIT-2.0.0-beta4
   make
   cd ..

   If you need specific C compiler flags, pass them to make as follows:

   make CFLAGS="..."

5. Build lupa:

   python setup.py build

Lupa change log

0.4 (2010-07-14)

• attribute read access on Lua objects, e.g. to read Lua table values from Python

• str() on Lua objects

• include .hg repository in source downloads

• added missing files to source distribution

0.3 (2010-07-13)

• fix several threading issues

• safely free the GIL when calling into Lua

0.2 (2010-07-13)

• propagate Python exceptions through Lua calls

0.1 (2010-07-12)

• first public release