I need clarification on Metatable.__index
lua, metatable
Solution
You need to understand the difference between `__index` and `__newindex`, and their relationship with the current contents of the main table.
`__newindex` is only called/accessed when all the following are true:
- When you are setting a value into the main table, via `tbl[index] = expr` (or equivalent syntax, like `tbl.name = expr`).
- When the key you are trying to set into the main table does not already exist in the main table.
The second one trips people up often. And that's your problem here, because `__index` is only accessed when:
- When the key being read from the main table does not already exist in the main table.
So if you want to filter every read from and write to a table, then that table must always be empty. Therefore, those reads and writes need to go into some other table you create for each new object. So your `new` function needs to create two tables: one that remains empty and one that has all the data in it.
Honestly, I wish Lua had a way to create just an empty piece of userdata that you could bind a user-defined metatable to, just to avoid these issues.
Problem
I asked earlier why my methods for a metatable weren't being located by Lua, and was told that by setting `__index` to my metatable, that it would resolve the issue, so I assumed that a method when called was searching by index in the metatable, but I've ran into an issue now that I need to use indexing brackets `[` and `]` on my metatable, so `__index`is assigned to return an index from a table inside of it, how do I resolve the functionality needs of both using methods, and use of indexing brackets I wrote a minimal example indicating the problem: ``` TestMetatable = {DataTable = {}} TestMetatable.__index = TestMetatable function TestMetatable.new() local Tmp = {} setmetatable(Tmp,TestMetatable) Tmp.DataTable = {1} return Tmp end function TestMetatable:TestMethod() print("Ran Successfully") end function TestMetatable.__index(self,index) return self.DataTable[index] end local Test = TestMetatable.new() -- both functionalities are needed print(Test[1]) Test:TestMethod() ```