Converting setfenv getfenv to Lua 5.2

[Georgios Petsagourakis <petsagouris+lual@...>]

Hello all,

As an exercise, I am trying to convert hige to be compatible with 5.2 
but as with orbit's htmlify_func() (I'll explain in the second part) 
there is trouble involving converting the parts that are using setfenv 
and getfenv.

In particular this piece of code:

    -- found at
https://github.com/nrk/hige/blob/f8ccf9/hige.lua#L6-L23
    local function merge_environment(...)
      local numargs, out = select('#', ...), {}
      for i = 1, numargs do
        local t = select(i, ...)
        if type(t) == 'table' then
          for k, v in pairs(t) do
            if (type(v) == 'function') then
              out[k] = setfenv(v, setmetatable(out, {
                __index = getmetatable(getfenv()).__index
              }))
            else
              out[k] = v
            end
          end
        end
      end
      return out
    end

As far as orbit is concerned:

I've gotten to a point that the piece of code found here:

    -- found at
https://github.com/keplerproject/orbit/blob/1f0c1f/src/orbit.lua#L330-L352
    local function htmlify_func(func)
      local tags = {}
      local env = { H = function (name)
                     local tag = tags[name]
                     if not tag then
                            tag = newtag(name)
                            tags[name] = tag
                     end
                     return tag
                     end
             }
      local old_env = getfenv(func)
      setmetatable(env, { __index = function (env, name)
                                     if old_env[name] then
                                     return old_env[name]
                                     else
                                     local tag = newtag(name)
                                     rawset(env, name, tag)
                                     return tag
                                     end
                                    end })
      setfenv(func, env)
    end

I can tell that it creates a new environment for the html tags 
function calls by which the calls are actually redirected to 
newtag() and then it sets that environment as the environment 
for those functions that use these calls.

In both of these cases it is difficult to understand how to make this
functionality happen in Lua 5.2 though with setfenv and getfenv missing.

Would someone be willing to help?