Ruby Value Objects
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Ruby Value Objects
#code #summaries #ruby #codesummary #value #objects
![# Code Summary for https://thoughtbot.com/blog/value-object-semantics-in-ruby # Part 2/4 : Value objects # 1. Should == each other # 2. Should NOT #equal? each other (as equal? should compare by identity) # 3. Should #hash to the same value # 4. Should #eql? each other (Ruby expects objects that have them same hash to be eql?) class Duration attr_reader :minutes def initialize(minutes) = @minutes = minutes def ==(other) = minutes == other.minutes alias_method :eql?, :== def hash = [self.class, minutes].hash end # #hash and #eql? are importyant as it allows the value object to be used as hash key events = { Duration.new(5) => [ 1, 2, 3], Duration.new(10) => [5, 6, 7] } events[Duration.new(5)] # will return [1, 2, 3] # Struct objects are compared by value by default Duration = Struct.new(:minutes) Duration.new(5) == Duration.new(5)](https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F04fcc227-4ff0-44dc-8fea-2be5bea1fdf5_1358x1294.png "# Code Summary for https://thoughtbot.com/blog/value-object-semantics-in-ruby # Part 2/4 : Value objects # 1. Should == each other # 2. Should NOT #equal? each other (as equal? should compare by identity) # 3. Should #hash to the same value # 4. Should #eql? each other (Ruby expects objects that have them same hash to be eql?) class Duration attr_reader :minutes def initialize(minutes) = @minutes = minutes def ==(other) = minutes == other.minutes alias_method :eql?, :== def hash = [self.class, minutes].hash end # #hash and #eql? are importyant as it allows the value object to be used as hash key events = { Duration.new(5) => [ 1, 2, 3], Duration.new(10) => [5, 6, 7] } events[Duration.new(5)] # will return [1, 2, 3] # Struct objects are compared by value by default Duration = Struct.new(:minutes) Duration.new(5) == Duration.new(5)")
