Immutable Style

An immutable style creates an updated value instead of changing the original value.

immutable_style.rb

bonus = 
original = { name: "Ada", score: 8 }

new_score = original[:score] + bonus
updated = original.merge(score: new_score)

original_score = original[:score]
updated_score = updated[:score]

puts "bonus=#{bonus}"
puts "original_score=#{original_score}"
puts "updated_score=#{updated_score}"
puts "same_object=#{original.object_id == updated.object_id}"

bonus = 
original = { name: "Ada", score: 8 }

new_score = original[:score] + bonus
updated = original.merge(score: new_score)

original_score = original[:score]
updated_score = updated[:score]

puts "bonus=#{bonus}"
puts "original_score=#{original_score}"
puts "updated_score=#{updated_score}"
puts "same_object=#{original.object_id == updated.object_id}"

bonus = 
original = { name: "Ada", score: 8 }

new_score = original[:score] + bonus
updated = original.merge(score: new_score)

original_score = original[:score]
updated_score = updated[:score]

puts "bonus=#{bonus}"
puts "original_score=#{original_score}"
puts "updated_score=#{updated_score}"
puts "same_object=#{original.object_id == updated.object_id}"

immutable update Ruby objects can be mutable, but methods like `merge` make it easy to create updated copies.