table.weakref

table.lua

do table.weakref -- protect against evil anti-GC indirect self-references
    --[[ sample usage:
        a = {}
        b = {a = a}
        a.b = table.weakref(b)
        a, b = nil, nil
        -- a and b *should* be collected
        -- to use b from a.b:
        print(a.b() == b)
    ]]
    = function(t)
        return setmetatable({__ref=t}, table._weakref_mt)
    end
    table._weakref_mt = {
        __mode = "v", -- DE MAGICKS!
        __call  = function(self)
            return rawget(self, "__ref")
        end,
    }
end
do table.weakproxy -- same as above, but with a metatable to make it transparent (warning: hacky!)
    --[[ sample usage:
        a = {}
        b = {a = a}
        a.b = table.weakproxy(b)
        a, b = nil, nil
        -- a and b *should* be collected
    ]]
    = function(t)
        return setmetatable({__ref=t}, table._weakproxy_mt)
    end
    table._weakproxy_mt = {
        __mode = "v", -- DE MAGICKS!
     -- __add    = function(l, r) end, -- TODO: Implement table.reference_mt.__add
     -- __sub    = function(l, r) end, -- TODO: Implement table.reference_mt.__sub
     -- __mul    = function(l, r) end, -- TODO: Implement table.reference_mt.__mul
     -- __div    = function(l, r) end, -- TODO: Implement table.reference_mt.__div
     -- __mod    = function(l, r) end, -- TODO: Implement table.reference_mt.__mod
     -- __pow    = function(l, r) end, -- TODO: Implement table.reference_mt.__pow
     -- __unm    = function(self) end, -- TODO: Implement table.reference_mt.__unm
     -- __concat = function(l, r) end, -- TODO: Implement table.reference_mt.__concat
        __len    = function(self)
            return #rawget(self, "__ref")
        end,
     -- __eq     = function(l, r) end, -- TODO: Implement table.reference_mt.__eq
     -- __lt     = function(l, r) end, -- TODO: Implement table.reference_mt.__lt
     -- __le     = function(l, r) end, -- TODO: Implement table.reference_mt.__le
        __index  = function(self, key)
            return rawget(self, "__ref")[key]
        end,
        __newindex  = function(self, key, value)
            rawget(self, "__ref")[key] = value
        end,
        __call  = function(self, ...)
            rawget(self, "__ref")(...)
        end,
        __tostring = function(self)
            return tostring(rawget(self, "__ref"))
        end,
    }
end