Mi Ruby l'anima

The love for Ruby and metaprogramming with DSLs

Transcript

2. MI L'ANIMA
3. WHY DO WE LOVE RUBY?
4. EASY TO READ
5. COMMUNITY ▸ 100k+ gem on rubygems.org ▸ 3rd repo language on GitHub1 1 according to GitHub Language Trends
6. RUBY ISN'T COOL ANYMORE AND WE ARE FINE WITH THAT.
7. TESTING CULTURE
8. RUBY ON RAILS
9. ALL THAT GLITTERS IS NOT GOLD
10. RUBY IS SLOW BUT RUBY 2.0 HAS MADE GOOD PROGRESS 2 2 Garbage collection in ruby 2.0
11. NOT SUITED FOR PARALLELISM 3 3 MRI have GIL lock, JRuby doesn't. More about GIL.
12. CODING TIME
13. DSL DOMAIN-SPECIFIC LANGUAGE
14. DSL [...] a computer language that's targeted to a particular kind of problem, rather than a general purpose language that's aimed at any kind of software problem.4 — Martin Fowler 4 Martin Fowler article
15. class Recipe attr_accessor :name, :ingredients, :difficulty # defines getters and setters def initialize @ingredients = [] end def add_ingredient(ingredient) ingredients << ingredient end def cook! puts "Cooking #{name} (#{difficulty})," puts "with: #{ingredients.join(", ")}." puts "Buon appetito!" end end
16. recipe = Recipe.new recipe.name = "spaghetti con polpette" recipe.difficulty = :easy recipe.add_ingredient("spaghetti") recipe.add_ingredient("polpa di pomodoro") recipe.add_ingredient("polpette") recipe.cook! "Cooking spaghetti con polpette (easy), with: spaghetti, polpa di pomodoro, polpette. Buon appetito!"
17. module RecipeBook @collection = {} def self.add(recipe) @collection[recipe.name] = recipe end def self.get(name) @collection[name] end end
18. recipe = Recipe.new recipe.name = "spaghetti con polpette" [...] RecipeBook.add(recipe) RecipeBook.get("spaghetti con polpette").cook! "Cooking [...]"
19. WE WANT THIS RecipeBook.add do name "Spaghetti con polpette" difficulty :easy ingredient "spaghetti" ingredient "passata di pomodoro" ingredient "polpette" end
20. ATTEMPT #1
21. module RecipeBook [...] def self.add(&block) recipe = Recipe.new recipe.instance_eval(&block) @collection[recipe.name] = recipe end [...] end
22. RecipeBook.add do self.name = "spaghetti con polpette" self.difficulty = :easy add_ingredient("spaghetti") add_ingredient("passata di pomodoro") add_ingredient("polpette") end
23. UGLY !
24. WE WANT THIS! RecipeBook.add do name "Spaghetti con polpette" difficulty :easy ingredient "spaghetti" ingredient "passata di pomodoro" ingredient "polpette" end
25. ATTEMPT #2
26. class RecipeBuilder attr_reader :recipe def initialize @recipe = Recipe.new end def name(name) recipe.name = name end def difficulty(difficulty) recipe.difficulty = difficulty end def ingredient(ingredient) recipe.add_ingredient(ingredient) end end
27. module RecipeBook @collection = {} def self.add(&block) builder = RecipeBuilder.new builder.instance_eval(&block) recipe = builder.recipe @collection[recipe.name] = recipe end def self.get(name) @collection[name] end end
28. RecipeBook.add do name("spaghetti con polpette") difficulty(:easy) ingredient("spaghetti") ingredient("passata di pomodoro") ingredient("polpette") end
29. RecipeBook.add do name "spaghetti con polpette" difficulty :easy ingredient "spaghetti" ingredient "passata di pomodoro" ingredient "polpette" end
30. !
31. REFACTORING
32. class RecipeBuilder attr_reader :recipe def initialize @recipe = Recipe.new end def name(name) recipe.name = name end def difficulty(difficulty) recipe.difficulty = difficulty end def ingredient(ingredient) recipe.add_ingredient(ingredient) end end
33. class RecipeBuilder attr_reader :recipe DELEGATED_SETTERS = [:name, :difficulty] def initialize @recipe = Recipe.new end def method_missing(method_name, *args) if DELEGATED_SETTERS.include?(method_name) recipe.send("#{method_name}=", *args) # e.g.: name=("spaghetti con polpette") else super end end def ingredient(ingredient) recipe.add_ingredient(ingredient) end end
34. BOOKS ▸ Practical Object-Oriented Design in Ruby ▸ Metaprogramming Ruby 2
35. QUESTIONS TIME
36. VI È VENUTA FAME? SOURCE CODE: HTTP://BIT.LY/1NWGAJT @delphaber @welaika