require File.expand_path(File.dirname(__FILE__) + '/edgecase') class AboutClasses < EdgeCase::Koan class Dog end def test_instances_of_classes_can_be_created_with_new fido = Dog.new assert_equal __, fido.class end # ------------------------------------------------------------------ class Dog2 def set_name(a_name) @name = a_name end end def test_instance_variables_can_be_set_by_assigning_to_them fido = Dog2.new assert_equal __, fido.instance_variables fido.set_name("Fido") assert_equal __, fido.instance_variables end def test_instance_variables_cannot_be_accessed_outside_the_class fido = Dog2.new fido.set_name("Fido") assert_raise(___) do fido.name end assert_raise(___) do eval "fido.@name" # NOTE: Using eval because the above line is a syntax error. end end def test_you_can_politely_ask_for_instance_variable_values fido = Dog2.new fido.set_name("Fido") assert_equal __, fido.instance_variable_get("@name") end def test_you_can_rip_the_value_out_using_instance_eval fido = Dog2.new fido.set_name("Fido") assert_equal __, fido.instance_eval("@name") # string version assert_equal __, fido.instance_eval { @name } # block version end # ------------------------------------------------------------------ class Dog3 def set_name(a_name) @name = a_name end def name @name end end def test_you_can_create_accessor_methods_to_return_instance_variables fido = Dog3.new fido.set_name("Fido") assert_equal __, fido.name end # ------------------------------------------------------------------ class Dog4 attr_reader :name def set_name(a_name) @name = a_name end end def test_attr_reader_will_automatically_define_an_accessor fido = Dog4.new fido.set_name("Fido") assert_equal __, fido.name end # ------------------------------------------------------------------ class Dog5 attr_accessor :name end def test_attr_accessor_will_automatically_define_both_read_and_write_accessors fido = Dog5.new fido.name = "Fido" assert_equal __, fido.name end # ------------------------------------------------------------------ class Dog6 attr_reader :name def initialize(initial_name) @name = initial_name end end def test_initialize_provides_initial_values_for_instance_variables fido = Dog6.new("Fido") assert_equal __, fido.name end def test_args_to_new_must_match_initialize assert_raise(___) do Dog6.new end # THINK ABOUT IT: # Why is this so? end def test_different_objects_have_difference_instance_variables fido = Dog6.new("Fido") rover = Dog6.new("Rover") assert_equal __, rover.name != fido.name end # ------------------------------------------------------------------ class Dog7 attr_reader :name def initialize(initial_name) @name = initial_name end def get_self self end def to_s __ end def inspect "" end end def test_inside_a_method_self_refers_to_the_containing_object fido = Dog7.new("Fido") fidos_self = fido.get_self assert_equal __, fidos_self end def test_to_s_provides_a_string_version_of_the_object fido = Dog7.new("Fido") assert_equal __, fido.to_s end def test_to_s_is_used_in_string_interpolation fido = Dog7.new("Fido") assert_equal __, "My dog is #{fido}" end def test_inspect_provides_a_more_complete_string_version fido = Dog7.new("Fido") assert_equal __, fido.inspect end def test_all_objects_support_to_s_and_inspect array = [1,2,3] assert_equal __, array.to_s assert_equal __, array.inspect assert_equal __, "STRING".to_s assert_equal __, "STRING".inspect end end