Ruby seen from a C# developer
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RUBY SEEN BY A C# DEVELOPEREmanuele DelBono - @emadb
I AM
I am a software engineer and web architect in CodicePlastico. I write web apps in C#, javascript e ruby.
IT ISN’T A RUBY TUTORIAL!
It’s a bunch of stuff that made me say WOW!
C# (2002)!
• Compiled, strongly typed
• OOP (multiparadigm)
• Delegate/lambda/enumerators
• ECMA standard
• Mono on Linux and MacOS
• “A better java”
RUBY (1995)
• Dynamic
• Open Source
• Interpreted
• Multi inheritance through Mixin
• Fully OOP
HELLO WORLD
using System;!public class Program {! public void Main() {! Console.WriteLine("Hello World"); }!}!
HELLO WORLD
p 'hello world'
RAILSclass Employee < ActiveRecord::Base! belongs_to :company! attr_accessible :name, :surname, :role! has_many :activities! before_save :update_role! scope :managers, -> { where(role: 'manager') }! ! def update_role! # ...! end! def foo! # ...! end !end
ALL CODE IS EXECUTED
class MyClass < (rand < 0.5 ? Array : Hash)!end!
WOW!
REAL OOP
class is an instance of class
class Cat end cat = Cat.new
puts cat.class.class.class !Class
puts cat #<Cat:0x007fa2bc13d5d8>
puts cat.class Cat
puts cat.class.class Class
Klazz = Class.new=> Klazz
puts Klazz=> Klazz
puts Klazz.class Class
k = Klazz.new => #<Klazz:0x007f8fc121ab58>
Foo = Class.new do def bar "I'm bar...an instance method of foo" end end !a = Foo.new p a.bar => "hello"
WOW!
SINGLETON METHODS
We can add methods to a single instance
class Cat def meow; ’meow’; end end
cat = Cat.new new_cat = Cat.new
def cat.argh 'argh' end
p cat.meow => "meow"
p cat.argh => "argh"p new_cat.argh NoMethodError: undefined method `argh' for #<Cat:0x007fda63085878>
?EIGENCLASS
THE OBJECT MODEL• Every object, classes included, has its
own “real class,” be it a regular class or an eigenclass
• The superclass of the eigenclass is the object class
• The superclass of the eigenclass of a class is the eigenclass of the class’s superclass
THE OBJECT MODEL
obj #obj
D
C
Object
#D
#C
#Object
Metaprogramming Ruby - Pag. 125
class C; end class D < C; end obj = D.new
WOW!
monkey patching“a way to extend or modify the runtime code of dynamic languages [...] without
altering the original source code.”
class String def foo to_s + ' fooed' end end
s = "hello"
puts s.foo=> "hello fooed"
REMOVE METHODS
class String remove_method :to_s end
WOW!
duck typing
When I see a bird that walks like a duck and swims like a duck and quacks like a
duck, I call that bird a duck http://en.wikipedia.org/wiki/Duck_typing
class Type1 def foo; "I'm type1"; end end !class Type2 def foo; "I'm type2"; end end
def get_class rand < 0.5 ? Type1 : Type2 end !t = get_class.new p t.foo
=> "I'm type2" #or I'm type1
METHOD INTERCEPTION
Using alias and monkey patching we can run through the execution
class Cat def meow p "meow" end end cat = Cat.new
Cat.class_eval do alias :meow_new :meow def meow p "i'm about to meow" meow_new p "did you hear me?" end end
cat.meow
=> "i'm about to meow" => "meow" => "did you hear me?"
METAPROGRAMMING
Metaprogramming is the writing of computer programs that write or manipulate other programs (or
themselves) as their data […]
http://en.wikipedia.org/wiki/Metaprogramming
class Cat def method_missing(method, *args) #do something without failing end end
METHOD MISSING
class Settings def initialize(options) options.each do |key, value| self.instance_variable_set "@#{key}", value self.class.send :define_method, key, proc{self.instance_variable_get("@#{key}")} self.class.send :define_method, "#{key}=", proc{|v| self.instance_variable_set("@#{key}", v)} end end endc = Settings.new YAML.load_file("config.yaml") !p c.title # => "metaprogramming ruby" p c.author # => "Paolo Perrotta" p c.pub_year # => "2010" !c.title = 'metaprogramming ruby 2.00’ p c.title # => "metaprogramming ruby 2.00”
HOOKS
Since all code is executed. You can intercept some “facts” about it.
inherited, append_features, included, extend_object, extended, initialize_copy,
const_missing
WOW!
BUT THERE’S MORE
> [1, 2, 3] * 3 == [1, 2, 3, 1, 2, 3, 1, 2, 3]
> 1_000_000
> a = a || []
> a = [1,2,3]; a[-1]
> [1,2,3].shuffle
> (0..9).each { ... }
> 3.times {...}
> def name=(value); ...
PHILOSOPHYI hope to see Ruby help every programmer in the world to be productive, and to enjoy programming, and to be happy. That is the primary purpose of Ruby language.
Yukihiro Matsumoto
o = Object.new!o.methods.count
=> 54
• ActiveRecord::Base => 367
• String => 161
• Fixnum => 128
SAME METRICS?
DIFFERENT WORLD?
RUBY PRO
• Simplicity
• REPL (irb, rails c, heroku run console)
• No ceremony
• One file app
• Community and frameworks
• Expressiveness (DSL)
CONS
• Freedom bring responsibility
• Performance
• No tools for refactoring
• Tests are mandatory (mmh…)
DOES IT WORTH?
LINGUISTIC RELATIVITY
“The principle of linguistic relativity holds that the structure of a language affects the ways in which its respective speakers
conceptualize their world.” Sapir–Whorf hypothesis
http://en.wikipedia.org/wiki/Linguistic_relativity
THE PRAGMATIC PROGRAMMER
“Learn at least one new language every year. Different languages solve the same problems in different ways. By learning several different approaches, you can help broaden your thinking and avoid getting stuck in a rut.”
The Pragmatic Programmer
MORE LANGUAGES ==
BETTER PROGRAMMER