in Lua 5.x what is Lua 4.0 "gettable" and "settable" event used to set tagmethods (like metamethods)?

Question

In lua 4.0 the tagmethod "gettable" allows to intercept the access to table elements. Each time there is an attempt to access a table element, the linked tagmethod for "gettable" event is called:

local t = { a=123 }
local tg = newtag()
settagmethod(tg, "gettable", 
  function(tbl, idx) print(tbl, idx) return rawget(tbl, idx) end )
settag(t, tg)
print(t.a)    -- <-- prints table: 0x7f9a8250acc0   a
              -- <-- then prints t.a value

What is the equivalent in Lua 5.xx ?

How can my code call a method each time the table is accessed in Lua 5.x?