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Does that work for inheritance? A hybrid of what you have and what's in the book does: 

-- obj.lua
local setmetatable = setmetatable
module(...)
local obj = _M
function obj.new(o)
  self.__index = self
  return setmetatable(o or {}, self)
end

-- subobj.lua
local obj = require("obj")
module(...)
local subobj = obj:new(_M)

Thanks again,
Geoff

On 28/04/2009, at 9:17 PM, Peter Cawley wrote:


My approach would be something like:

-- obj.lua
local setmetatable = setmetatable
module(...)
local obj = _M
obj.__index = obj -- obj doubles as a metatable
function obj.new()
 local self = setmetatable({}, obj)
 return self
end
function obj:method(...)
end

-- usage
require "obj" -- OR local obj = require "obj"
o = obj.new()
o:method("etc.")

On Tue, Apr 28, 2009 at 5:46 AM, Geoff Leyland
<geoff_leyland@fastmail.fm> wrote:

On 28/04/2009, at 1:09 PM, David Manura wrote:


On Mon, Apr 27, 2009 at 4:15 PM, Geoff Leyland wrote:
The default package.path contains './?.lua', but not './?/ init.lua'. Obviously, it's easy to add, so there's no problem, but I often find 
myself
adding it.  Any reason it's not there by default?
Perhaps we should instead ask why init.lua it not eliminated entirely. It is not necessary[1], and I think it complicates things[2]. Module 
authors need to decide which form to use, and it's near certain that
different module authors will choose different conventions.  Module
users or Lua distributions, when adding a directory to the Lua search 
path, may need to add both forms in general, though omitting the
latter might usually work or might appear to initially work. It also opens the ambiguity where ".../a/init.lua" could represent the module 
"a" or a module actually named "a.init".  Finally, it makes module
search errors longer for the end-user:
While we're discussing packages, what's the logic behind the difference 
between what's returned by require and what's put in _G?

mod.lua:
module(...)
a = 1
return 3


print(require("mod"))

2

print(type(mod))

table
This may seem irrelevant, but I often put a single class or function into a 
file:

obj.lua:
local setmetable = setmetatable
module(...)
obj = {}
function obj:new()
self.__index = self
return setmetatable({}, self)
end

and create a new obj I have to go:


require("obj")
o = obj.obj:new()


which is a bit awkward.
An alternative is to put a "return obj" at the end of obj.lua, and then I 
need to go

local obj = require("obj")
o = obj:new()


Where I have to add the "local obj ="

One workaround is:

obj.lua:
local setmetable = setmetatable
module(...)
function new(self)
self.__index = self
return setmetatable({}, self)
end


require("obj")
o = obj:new()
But I kind of get the feeling I'm not Doing The Right Thing in all these cases. I don't have any solution to this, or any strong opinions, just 
wondering if anyone has a better idea.

Cheers,
Geoff