Re: anti...require?

[steve donovan <steve.j.donovan@...>]

On Sat, Jan 31, 2009 at 6:33 PM, Luiz Henrique de Figueiredo
<lhf@tecgraf.puc-rio.br> wrote:
> You cannot set __gc for tables. But you can say use a udata as upvalue for
> all functions registered in the module and then clean up when that udata
> is collected.
>

This shows a little module that encapsulates this pattern:

-- atend.lua
local obj = newproxy(true)
local mt = getmetatable(obj)
local atend_list = {}

mt.__gc = function()
    for _,fun in ipairs(atend_list) do
        fun()
    end
end

mt.__call = function(obj,fun)
    table.insert(atend_list,fun)
end

return obj

Then, to add finalization code to any module, do this:

require('atend')(function()
    -- any finalization code for this module
    print "finis"
end)

I've tested this with a few modules and things work as expected. Note
that it requires the undocumented function newproxy to make a
zero-length userdata (the garbage-collect metamethod __gc doesn't work
for regular tables)

steve d.