Re: Packaging and importing

[Tomas <tomas@...>]

	Hi,

> > Thanks for the help so far. My big issues still have to do with isolating 
> > namespaces. For instance, what about the problem I mention above? Are 
> > modules required by "b" isolated from those required in "a", like they are 
> > in Python?
>
> No. All modules are available globally. If both "a" and "b" require"c",
> both will share the same module. That said, Lua is powerful enough for
> you to override this behavior. I believe VEnv, used with CGILua, does that. 
> Once again, Lua gives you the power. If you need a sandbox, it can be done.
	What I have to add to Diego's explanation is that a module
that needs a certain global could store it in a local not only to gain
some speed, but also to guarantee that this global will be exactly the
same during its execution.  For example:

require"c"
local f = c.f
module"a"

function x (s)
	f(s)
	c.g(s)
end

	`f' is the local copy of `c.f', made after the require"c"
(this required library could be an already loaded library, as Diego
told); `c.g' will be _M.c.g (_M is the module's global table created
by `module()'), but as `c' is inherited from the original globals table,
it will be _M._G.c.g, which could be easily changed outside the library.

> > Also, has anyone made a proposal for how you can promote all the members of 
> > "a" into the namespace of the module that requires "a"?
	Why don't you inherit the symbols from "a" with something
like:

require"a"
_M = {}
setmetatable (_M, { __index = a }) -- inherit from "a"
setfenv (1, _M) -- new environment (global table)

	If "a" inherits from the global table you'll get all global
through it!

	Tomas