Question

Hello,

I am studying Ruby through RubyMonk. I have a doubt with this exercise:

In this exercise, change push to return 10 as per
A = 10 in the topmost level, outside the Kata module.

module Kata
A = 5
module Dojo
B = 9
A = 7

class ScopeIn
def push
A
end
end
end
end

A = 10
::push.A = 10
puts "#{Kata::Dojo::ScopeIn.new.push}"

Can someone give the solution?

Answer 1

This is a constant lookup exercise by the looks of it, so you should know the '::' is a constant lookup operator that looks up the array constant only in the perimeter module.
So:
```
module Kata
A = 5
module Dojo
B = 9
A = 7
class ScopeIn
def push
::A
end
end
end
end
A = 10
```
(Kata::Dojo::ScopeIn.new.push should return 10)

Explanation:
If you prepend a constant with '::' (without a parent, Kata and Dojo in this example), the scoping will happen on the topmost level. In our case the top most level is the \(A = 10\) class (notice it is the last line), and because \(A = 10\) is outside of the module Kata it is considered to be the 'highest class'.

Summary of Explanation:
::A returns 10 since it scopes the topmost level. This is because the parents (Kata, and Dojo) are not present.

Source:
Ruby syntax cheatsheet:
https://github.com/savini/cheatsheets/raw/master/ruby/RubyCheat.pdf

Answer 2

Thank you Opcode. It has work!!! :D

Answer 3

wow