171 lines
3.6 KiB
Ruby
171 lines
3.6 KiB
Ruby
require File.expand_path(File.dirname(__FILE__) + '/edgecase')
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class AboutClassMethods < EdgeCase::Koan
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class Dog
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end
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def test_objects_are_objects
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fido = Dog.new
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assert_equal __, fido.is_a?(Object)
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end
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def test_classes_are_classes
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assert_equal __, Dog.is_a?(Class)
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end
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def test_classes_are_objects_too
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assert_equal __, Dog.is_a?(Object)
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end
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def test_objects_have_methods
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fido = Dog.new
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assert fido.methods.size > _n_
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end
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def test_classes_have_methods
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assert Dog.methods.size > _n_
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end
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def test_you_can_define_methods_on_individual_objects
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fido = Dog.new
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def fido.wag
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:fidos_wag
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end
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assert_equal __, fido.wag
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end
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def test_other_objects_are_not_affected_by_these_singleton_methods
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fido = Dog.new
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rover = Dog.new
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def fido.wag
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:fidos_wag
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end
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assert_raise(___) do
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rover.wag
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end
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end
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# ------------------------------------------------------------------
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class Dog2
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def wag
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:instance_level_wag
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end
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end
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def Dog2.wag
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:class_level_wag
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end
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def test_since_classes_are_objects_you_can_define_singleton_methods_on_them_too
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assert_equal __, Dog2.wag
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end
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def test_class_methods_are_independent_of_instance_methods
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fido = Dog2.new
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assert_equal __, fido.wag
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assert_equal __, Dog2.wag
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end
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# ------------------------------------------------------------------
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class Dog
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attr_accessor :name
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end
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def Dog.name
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@name
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end
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def test_classes_and_instances_do_not_share_instance_variables
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fido = Dog.new
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fido.name = "Fido"
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assert_equal __, fido.name
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assert_equal __, Dog.name
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end
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# ------------------------------------------------------------------
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class Dog
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def Dog.a_class_method
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:dogs_class_method
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end
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end
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def test_you_can_define_class_methods_inside_the_class
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assert_equal __, Dog.a_class_method
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end
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# ------------------------------------------------------------------
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LastExpressionInClassStatement = class Dog
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21
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end
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def test_class_statements_return_the_value_of_their_last_expression
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assert_equal __, LastExpressionInClassStatement
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end
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# ------------------------------------------------------------------
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SelfInsideOfClassStatement = class Dog
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self
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end
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def test_self_while_inside_class_is_class_object_not_instance
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assert_equal __, Dog == SelfInsideOfClassStatement
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end
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# ------------------------------------------------------------------
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class Dog
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def self.class_method2
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:another_way_to_write_class_methods
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end
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end
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def test_you_can_use_self_instead_of_an_explicit_reference_to_dog
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assert_equal __, Dog.class_method2
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end
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# ------------------------------------------------------------------
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class Dog
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class << self
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def another_class_method
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:still_another_way
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end
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end
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end
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def test_heres_still_another_way_to_write_class_methods
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assert_equal __, Dog.another_class_method
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end
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# THINK ABOUT IT:
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#
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# The two major ways to write class methods are:
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# class Demo
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# def self.method
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# end
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#
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# class << self
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# def class_methods
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# end
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# end
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# end
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#
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# Which do you prefer and why?
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# Are there times you might prefer one over the other?
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# ------------------------------------------------------------------
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def test_heres_an_easy_way_to_call_class_methods_from_instance_methods
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fido = Dog.new
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assert_equal __, fido.class.another_class_method
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end
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end
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