is it possibe to check if a new value was added to a table or dictionary?

For example:

t = {}
table.insert(t,1,"A") 
t["hi"] = "a"

Is it possible to execute a function whenever they are called? I tried with metatables but looks like table.insert and metatables dont go well together. Please help.

According to Nifim on Stack Overflow, you can run this code

local function listener(k,v)
  print( "new entry added: \n\tKey = " .. k .. "\n\tValue = " .. v)
end

local metaTable

do
  local protectedTable = {}
  metaTable = {
    __index = function (t,k)
      return protectedTable[k]
    end,
    __newindex = function (t,k,v)
      protectedTable[k] = v   -- update original table
      listener(k,v)
    end
  }
end

local t = setmetatable({},metaTable)

t.text = "Hello!"
print(t.text)

More information here.