on_hit.lua

local delegates = {}

local function OnEvent(evt, cb)
    local cb_dump = string.dump(cb)
    delegates[evt] = cb_dump
end

-- declare callbacks
OnEvent('hit', function(evt)
    damage(evt.source)
end)

-- create runtime
local rt_env = {
    damage = function(id)
        print('hitting on target:'..id)
    end
}

local runtime = {}
for k, v in pairs(delegates) do
    runtime[k] = load(v, k, 'b', rt_env)
end

-- dispatch
runtime['hit']{ source = 253 }
-- prints 'hitting on target: 253'