Strange meta __newindex behavior
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- Subject: Strange meta __newindex behavior
- From: Alan Hightower <alan@...>
- Date: 2007年3月24日 09:46:22 -0400 (EDT)
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
--
-------------
Alan Hightower - alan@alanlee.org