Question

I’m new to Lua and I want to create a table [doh] which would store values like:

parent.child[1].value = "whaterver"
parent.child[2].value = "blah"

however, most often there’s only one child, so it would be easier to access the value like this:

parent.child.value

To make things simpler, I would like to store my values, in a way, that

parent.child[1].value == parent.child.value

But to do this I would have to store this value twice in the memory.
Is there any way I could do it, so that:

parent.child.value points to parent.child[1].value

without storing the value twice in the memory?

Additional question is, how to check how much memory does a table take?

Answer 1

but the value will be stored as string, so it’s a string that needs to
be referenced in both places, not table.

First, all types (except booleans, numbers and light userdata) are references – if t is a table and you do t2 = t, then both t and t2 are references to the same table in memory.

Second thing – string are interned in Lua. That means that all equal strings, like "abc" and the result of "ab".."c" are actually a single string. Lua also stores only references to strings. So you should not worry about memory – there is only a single instance of the string at a time.

You can safely do parent.child.value = parent.child[1].value, you will only use a memory for one slot in a table (a few bytes), no string will be copied, only referenced.