Convert a string to an existing class instance

Question

Given a class instance and a string, how do I convert the string to refer to the instance?

class Room
  def enter
    puts "Welcome!"
  end
end

# Rooms are predefined
lounge = Room.new
kitchen = Room.new
study = Room.new

puts "Which room would you like to go to?"
print "> "
room = gets.strip

# User types "lounge"

room.enter # => undefined method `enter' for "lounge":String (NoMethodError)

I understand why I'm getting NoMethodError, but I haven't been able to work out how to convert the room string to refer to the existing instance of Room named lounge.

Answer 1

perhaps trying to map rooms and get them by key?

class Room

  def enter
    puts "Welcome!"
  end
end

# Rooms are predefined
rooms = %w[lounge kitchen study].inject({}) { |f,c| f.update c => Room.new }

puts "Which room would you like to go to?"
print "> "
if room = rooms[gets.strip]
  room.enter
end

Or even simpler:

class Room

  def initialize room_type
    @room_type = room_type
  end

  def enter
    return puts 'Unsupported room type' unless %w[
      lounge kitchen study
    ].include?(@room_type)
    puts "Welcome to #{@room_type}!"
  end

end

puts "Which room would you like to go to?"
print "> "
room = Room.new(gets.strip)
room.enter