local last_key = -1
local meta = {
__index = function(meta, key)
if key > last_key then
last_key = key
return "a"
else
return "bb"
end
end,
}
local t = setmetatable({}, meta)
print(table.concat(t, "", 1, 0x1 << 30))
Never do this in a production code.
You're relying on unspecified behavior here.
When evaluating an _expression_, Lua does not guarantee the order of subexpressions
(unless it is defined explicitly, e.g by operator precedence rules).
In particular, Lua does not guarantee the order of reading table elements inside table.concat.
Think what would happen with your code if table.concat read the table in reverse direction.
