Lua Quick Start Guide

__newindex

The __newindex meta method is complementary to the __index meta method. Where __index is used to retrieve values from missing keys in a table, __newindex is used to assign values to missing keys. The __newindex method takes three arguments:

• The table that is being operated on
• The missing key
• The value being assigned

Here is an example of using the __newindex meta method:

x = { }y = { }z = {  __index = function(table, key)    return z[key]  end,  __newindex = function(table, key, value)     z[key] = value  end}setmetatable(x, z)setmetatable(y, z)x.foo = "bar"print (x.foo) print (y.foo)print (z.foo)

In this example, both tables x and y have meta table z. The z meta table has an __index meta method, which searches for a key within z whenever ...