Strange meta __newindex behavior

[Alan Hightower <alan@...>]

Hello all.  New to Lua and just joned the list with a question.  Forgive 
me if it is already answered somewhere else.  I tried to do due dilligence 
in looking for the solution first.  I'm having a problem that just seems 
like a Lua bug.

I am using Lua as a config/control language for a new project.  I have a 
part of the Lua object tree I am trying to shadow so that I get 
notificatin of both assignments and function calls anywhere in the tree 
(as nearly all of it has direct control implications when changed).

I start by setting up a meta table for a root table like such:

root = {}
root._hidden_vals = {}
root._my_meta = {}
root._my_meta.__index = root._hidden_vals
root._my_meta.__newindex = _proc_lua_assignment
setmetatable (root, root._my_meta)

Then, whenever the C function associated with _proc_lua_assignment gets 
called, it performs needed notifications in C then assigned the value to 
the _hidden_vals sub table.  If the assignment operand is a LUA_TTABLE, it 
set's up similar code for the new table.  My problem is that:

   root.sub1 = {}; root.sub1.foo = bar
or
   root.sub1 = { foo = bar }

both work giving me proper notifications, however,

   root.sub1.foo = bar

alone performs the same Lua behavior (adds a new member to root with type 
table called sub1 with itself assigned a table containing foo = bar) yet I 
never get a __newindex meta call in C for the new assignment to root.  It 
would seem that since both cases are adding a new member to root, where 
one did not exist before, I sould get a notify call or the Lua instruction 
should fail.

Confused,

-Alan

--
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Alan Hightower - alan@alanlee.org