module_nesting_lookup

🚀 Understanding Constant Lookup in Nested Modules

Ruby searches constants lexically before going to ancestors. Nesting modules affects how constants are resolved, so structure your modules to avoid unexpected lookups.

module Outer
  X = 'outer'

  module Inner
    X = 'inner'

    def self.value
      X            # 'inner' from current scope
    end

    def self.outer_x
      ::Outer::X  # 'outer' using top-level lookup
    end
  end
end

puts Outer::Inner.value      # => "inner"
puts Outer::Inner.outer_x    # => "outer"