Class declarations in Ruby with lexical scopes vs closures

class.rb

require 'primalize'

# Because TicketOwnerSerializer is a constant, it is available
# anywhere in the app. We could nest it inside of TicketSerializer,
# but it has to exist before TicketSerializer's attributes declaration,
# so it would push that down.
class TicketOwnerSerializer < Primalize::Single
  attributes(
    id: string,
    name: string,
    email: string,
  )
end

class TicketSerializer < Primalize::Single
  attributes(
    id: string,
    title: string,
    description: string,
    owner: primalize(TicketOwnerSerializer) { |owner|
      owner || DEFAULT_OWNER
    },
  )
  
  # This is available anywhere in the app as TicketSerializer::DEFAULT_OWNER
  # We could make it a private_constant
  DEFAULT_OWNER = OpenStruct.new(
    id: '',
    name: 'Unassigned',
    email: '[email protected]',
  )
end

closure.rb

require 'primalize'

# These local variables can't be used outside of this file,
# making them actually private.
ticket_owner_serializer = Class.new(Primalize::Single) do
  attributes(
    id: string,
    name: string,
    email: string,
  )
end

default_owner = OpenStruct.new(
  id: '',
  name: 'Unassigned',
  email: '[email protected]',
)

TicketSerializer = Class.new(Primalize::Single) do
  attributes(
    id: string,
    title: string,
    description: string,
    owner: primalize(ticket_owner_serializer) { |owner|
      owner || default_owner
    },
  )
end