Editing a subtable inside a maintable using a function inside the maintable

Question

Is it possible to edit the contents of a table which is inside another table using a function?

local MainTable = {
  subtable = {
    x = 0,
    y = 0
 }, 

 addX = function() 
  subtable.x = subtable.x + 1
 end
}

I'm getting the error attempt to index ? (a nil value) Is it possible to achieve this? It works outside the table, I used:

print(MainTable.subtable.x+1)

How come it doesn't work inside the table? Does tables being objects play a role?

Thank you!

Answer 1

Lua tables aren't objects; just because you're declaring addX inside MainTable, it is not aware of anything else inseide MainTable.

One solution would be:

local MainTable
MainTable = {
...
   addX = function()
      MainTable.subtable.x = MainTable.subtable.x + 1
   end
}

but a better way would be

local MainTable = {
   subtable = {
      x = 0,
      y = 0
   }
}

function MainTable:addX() 
   self.subtable.x = self.subtable.x + 1
end

-- Use it as:
MainTable:addX()