RubyAccessors created by fijiaaron - https://repl.it/@fijiaaron/RubyAccessors

foo.1.rb

class Foo
  # initialize instance variables
  def initialize(bar="bar", baz="baz")
    @bar = bar
    @baz = baz
  end
end

foo.2.rb

class Foo
  # initialize instance variables
  def initialize(bar="bar", baz="baz")
    @bar = bar
    @baz = baz
  end

  # generate default getters and setters
  attr_accessor :bar, :baz
end

foo.3.rb

class Foo
  # initialize instance variables
  def initialize(bar="bar", baz="baz")
    @bar = bar
    @baz = baz
  end

  # generate default getters and setters
  attr_accessor :bar, :baz

  # add custom getter
  def bar()
    return @bar.capitalize()
  end
end

foo.4.rb

class Foo
  # initialize instance variables
  def initialize(bar="bar", baz="baz")
    @bar = bar
    @baz = baz
  end

  # generate default getters and setters
  attr_accessor :bar, :baz

  # add custom getter
  def bar()
    return @bar.capitalize()
  end

  # add custom setter
  def baz=()
    @baz = @baz.reverse()
  end
end

main.rb

require_relative("test.rb")

 # initialize class with private instance variables
class Foo
  def initialize(bar="bar", baz="baz")
    @bar = bar
    @baz = baz
  end
end

# create global foo to test
$foo = Foo.new()

test("no accessors")

# add default getters and setters
class Foo
  attr_accessor :bar, :baz
end

test("attr_accessor")

# add custom getter
class Foo
  def bar()
    @bar.upcase()
  end
end

test("custom getter")

 # add custom setter
class Foo
  def baz=(baz)
    @baz = baz.reverse()
  end
end

# set instance variable
$foo.baz = "baz"

test("custom setter")

test.rb

def test(message)
  begin
    puts "Test with #{message}"
    puts $foo.bar, $foo.baz
  rescue StandardError => e  
    puts e.message  
  end

  puts("\n")
end