How to access a ruby variable in another class?-CodePudding

How can I access the name variable in the game class, when I assign it in the Player Class? I am slightly confused about classes inheritance and scope. (Ruby)

class Game 
  attr_accessor :name

  def display_name
    puts "Name is #{@@name}"
  end 
end 

class Player 
  
  attr_accessor :name

  def get_name
    puts "What is your name? "
    @@name = gets.chomp
  end  

end 


player = Player.new()
player.get_name
game = Game.new()
game.display_name()

Thanks

CodePudding user response：

Player and Game are two different classes and not connected to each other. And two different instance also know nothing about each other in your example.

If you want to read an instance's variable from another instance then you need to pass the first instance to the other one to have a reference to it and be able to call a method on it.

In the context of your example with a Game and a Player that might look like the following (there are other way possible).

For example like this:

class Game 
  def initialize(player) # allows to pass a player when a game is created
    @player = player     # assigns the player to a variable for later use
  end

  def display_name
    puts "Name is #{@player.name}"   # call `name` on the stored variable
  end 
end 

class Player 
  attr_reader :name

  def get_name
    puts "What is your name? "
    @name = gets.chomp
  end  
end 

player = Player.new
player.get_name
#=> What is your name? 
#=> Peter Parker

game = Game.new(player)
game.display_name
#=> Name is Peter Parker

Please also note that instance variables in Ruby have only one @ at the beginning.

CodePudding user response：

@@name should be changed to @name because

@@ sets a class variable
@ sets an instance variable

and attr_accessor only works with instance variables

instance variables are 'linked' to their object

class Player
  attr_accessor :name
end

a = Player.new  # create first object
b = Player.new  # create second object

a.name = "Gwen"
b.name = "Toph"

puts a.name  
# => Gwen

puts b.name  
# => Toph

to access instance variables of an object, you can pass the object into your method

class Game 
  def display_name(player)
    puts "Name is #{player.name}"
  end 
end

game = Game.new

game.display_name(a)
# => Name is Gwen

game.display_name(b)
# => Name is Toph