SamGerber-zz

class Universe
  attr_reader :answer

  def initialize
    @answer = "42"
  end
end

universe = Universe.new   # => #<Universe:0x007f644d49de10 @answer="42">
universe.answer           # => "42"

SamGerber-zz

class Universe
  def initialize
    @answer = "42"
  end

  def answer
    return @answer  # Explicit return for clarity
  end
end

SamGerber-zz

class Universe
  def initialize
    @answer = "42"
    puts @answer    # Get @answer and pass it to Kernel#puts.
  end
end

universe = Universe.new   # printed 42 and returned <Universe:0x007fcdef8fb000 @answer="42">

SamGerber-zz

class Universe
  attr_writer :answer
end

universe = Universe.new     # => #<Universe:0x007f9ac4572e78>
universe.instance_variables # => []
universe.answer = "42"      # => "42"
universe.instance_variables # => [:@answer]

SamGerber-zz

class Universe
  def answer=(something)
    @answer = something
  end
end

universe = Universe.new     # => #<Universe:0x007f639f31b8e8>
universe.instance_variables # => []
universe.answer = "42"      # => "42"
universe.instance_variables # => [:@answer]

SamGerber-zz

class Universe
  def initialize
    @answer = "42"
  end
end

universe = Universe.new     # => #<Universe:0x007f4b34292288 @answer="42">
universe.instance_variables # => [:@answer]

SamGerber-zz

class Universe
  def initialize
    @answer = "42"
  end
end

universe = Universe.new     # => #<Universe:0x007f4b34292288 @answer="42">
universe.instance_variables # => [:@answer]