lua: why can't I use the name of the package? - lua

Question

Based on SimpleLuaClasses I've done a class in a file:
require 'class'
Session = class(function(self)
self.session_name = "l_sid"
end)
function Session:init(r)
self.session_id = r:getcookie(self.session_name)
if not self.session_id then
self.session_id = r:sha1(tostring(r.log_id) .. r.clock())
r:setcookie({
key = self.session_name,
value = self.session_id
})
end
end;
Now I'm trying this:
local session = require 'session'
function handle(r)
local s = Session()
s:init(r)
end
The previous code works. If I try local s = session.Session() it doesn't work.
When I try this, I get this error:attempt to index upvalue 'session' (a boolean value).
Why?

Answer 1

The return value of the require function is the value returned from your module. For example, if you create a file "foo.lua" with the following contents
-- This is foo.lua
return 17
When you do in another file
local x = require 'foo'
print(x)
Its going to print 17.
In your case, in order to have session.Session work you would need to return a table with a Session field from "session.lua"
return { Session = Session }
Alternatively, you can also just return Session directly if you aren't returning anything else
-- in session.lua
return Session
-- in the other file
local Session = require 'session'
Finally, the reason your first sollution is working is that you are defining Session as a global variable, that is seen from every module. I would recommennt avoiding globals as much as possible so you can turn Session into a local in session.lua
local Session = class(function() ... end)
Compiling everything together, here is how your fiull session.lua file should look like
require 'class'
local Session = class(function(self)
self.session_name = "l_sid"
end)
function Session:init(r)
self.session_id = r:getcookie(self.session_name)
if not self.session_id then
self.session_id = r:sha1(tostring(r.log_id) .. r.clock())
r:setcookie({
key = self.session_name,
value = self.session_id
})
end
end;
return Session

Answer 2

Here's a version that works:
--[[
--------------------------------------------------------------------
Classe Session
]]--
require 'class'
local session = {}
session.Session = class(function(self)
self.session_name = "l_sid"
end)
function session.Session:init(r)
self.session_id = r:getcookie(self.session_name)
if not self.session_id then
self.session_id = r:sha1(tostring(r.log_id) .. r.clock())
r:setcookie({
key = self.session_name,
value = self.session_id
})
end
end;
return session