Re: Obtaining references to a given object?

[Andrew Starks <andrew.starks@...>]

On Fri, Sep 13, 2013 at 9:15 PM, Marc Lepage <mlepage@antimeta.com> wrote:
>
> So, in that context, any suggestions? Some way to automate the hook ups or the actual update of objects referring to objects when the referred objects change? (Or their properties?)


Here is a silly toy version of what I mean:

local _model = {}

local subs = {}
local model = setmetatable({},
{
    __index = _model,

    __newindex = function(t, i, v)

        _model[i] = v
        if subs[i] then
            for i, cb in ipairs(subs[i]) do
                local success, msg = cb(v)
                --or local success, msg = coroutine.resume(cb, v)
                if not success then return nil, msg end

            end
            if not v then
                subs[i] = nil
            end
        elseif v then
            subs[i] = {} --make new table for callbacks
        end
    end
})


model.foo = "bar"
for x = 1, 3 do
    subs.foo[#subs.foo + 1] = function(v)
        print("CB " .. x ..": Got:",v)
        return true
    end
end

model.foo = "baz"
model.foo = "dizzle"
model.foo = nil
assert(subs.foo == nil, "subs.foo should be gone.")