NAME

       python-lua - using lua scripts from python

SYNOPSIS

       import lua

       lua_handle = lua.lua (debug = False)

       lua_handle.run (script = None, var = None, value = None, name = ´python string´)

       lua_handle.run_file (script_file)

       lua_handle.module (name, my_module)

       lua_table._dict ()

       lua_table._list ()

DESCRIPTION

       The  lua  module  interfaces  Python  code  to  the Lua library, thus allowing Lua scripts to be run from
       Python. For most operations, a lua.lua object must be created. This object does all  the  work.  Creating
       multiple  lua  objects from one Python program should work, but is untested. When creating a lua instance
       with debug set to False (the default), it will automatically run self.run (´debug  =  nil´),  which  will
       disable the debugging library.

       lua.run  is  the  main  entry point into lua code. It allows running a script (which may be uncompiled or
       compiled lua code). It can also be used to set the value of a global lua variable to  any  Python  value.
       script may be omitted, in which case only the assignment is performed. If var is omitted, only the script
       is  run.  If  both  are  present, the variable is assigned before the script is run. To assign a variable
       inside a table, you can use lua_handle.run (´table.foo = tmp´, ´tmp´, value). The name is used for  error
       reporting.

       When  using  Python objects from Lua, their python operations are used when invoked. For example, the add
       function will be called when something is added to the object in lua. This  is  particularly  useful  for
       functions,  which  can be called from lua this way. Note that passing a method to Lua works fine, but the
       library will raise an exception if Lua tries to call it with  a  different  object  instance.  Also,  the
       library  may  raise  exceptions  when  lua  scripts  don´t  expect  them,  for example when referencing a
       nonexistent member.

       lua.run_file is similar to lua.run, but it takes a filename where  the  code  is  located.  It  does  not
       support variable assignment, so if that is required, a call to lua.run should be used first.

       lua.module  allows  importing  an  object into lua as a module. This works reasonably well, but there are
       some limitations, see BUGS.

       Lua tables are wrapped in a Python object when they are returned. When changes are made  to  this  Python
       object,  the  change  is  passed  through to the lua object. In other words, Lua remains the owner of the
       table.

       Lua doesn´t use integers, but only floats. Because it is quite normal to use a Lua table as a list, there
       is a function to convert a table wrapper to a list. This is what lua_table._list () does. The  underscore
       is  to  avoid  name collisions with table members. There are two things to remember when using it. First,
       Lua starts counting at 1, but Python starts at 0. A value called a[3] in Lua is called a._list  ()[2]  in
       Python.  Second,  when using _list on a table which contains non-integer elements, those elements are not
       present in the returned list.

       The table wrapper supports most Python operations, but it can be useful to copy it to  a  dict.  This  is
       what  lua_table._dict  ()  does. Changes made to this dict are not reflected in the lua table that it was
       copied from.

SECURITY CONSIDERATIONS

       Lua has the ability to load any libraries from the system. This means that Lua should  not  be  used  for
       scripts from untrusted sources.

BUGS

       Lua only supports plain tables, not user objects, as module definitions. This means that no callbacks can
       be  added  for events which happen in the top level of the module. In particular, when a Python module is
       used as a lua module (which is the usual case), a list is built at registration time and passed  to  lua.
       When  new variables are added to the Python module, or existing variables are changed so they link to new
       objects, those changes will not be reflected in lua. Similarly,  such  changes  made  from  lua  are  not
       visible in Python. Changing the contents of variables is not affected by this problem.

       As  a  workaround, when changing or creating such variables from Python, you can manually add them to lua
       as well, using lua.run (var = ´name´, value =<module.name>). When using variables  which  may  have  been
       changed by lua, instead of using their value directly from the python module, use lua.run (name).

AUTHOR

       Python-lua was written by Bas Wijnen <wijnen@debian.org>

                                                   August 2012                                     PYTHON-LUA(7)