Re: Deprecating setfenv()
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- Subject: Re: Deprecating setfenv()
- From: steve donovan <steve.j.donovan@...>
- Date: Sat, 9 Jan 2010 16:16:42 +0200
On Sat, Jan 9, 2010 at 4:07 PM, Bertrand Mansion <lua@mamasam.net> wrote:
> just a clear sign that these functions are lower-level and that there
> are now more user-friendly ways to achieve similar things.
But not _all things_. I'm thinking of Leo's use-case, where he has one
function which he wants to evaluate efficiently for a lot of different
contexts.
Here's David M's idea of private module environments done without setfenv:
-- closed_module.lua
local setmetatable,rawset,_G = setmetatable,rawset,_G
return function(name)
local mod = module(name)
local env,meta = {_M=mod._M,_NAME=mod._NAME,_PACKAGE=mod._PACKAGE},{}
env._SELF = env
meta.__index = _G
function meta.__newindex(t,key,val)
rawset(mod,key,val)
rawset(env,key,val)
end
setmetatable(env,meta)
return env
end
And the modules look like this:
in require 'closed_module' (...) do
function first (x)
second(x)
end
function second (x)
print(x)
end
end
The idea is still doable, i.e. that you can put any arbitrary junk in
the environment of the module without bothering the global table.
steve d.