This document provides an overview of Ruby and Rails. It notes that Ruby was created in Japan by Yukihiro Matsumoto in 1993. Rails was created in Denmark by David Heinemeier Hansson in 2004 to build the BaseCamp application. It compares package ecosystems across languages and frameworks, demonstrating that RubyGems has the most packages of the listed options. It also shows multiple ways to write the same program in Ruby and discusses best practices like testing, short methods, and extracting duplicate logic.

1. RUBY (AND RAILS)
Jan Berdajs
@mrbrdo

2. RUBY
•
Japan
•
Yukihiro Matsumoto a.k.a. Matz
•
24. Feb. 1993
•
Matz is nice and so we are nice
(MINASWAN)

3. RAILS
•
Denmark
•
David Heinemeier Hansson a.k.a
DHH
•
BaseCamp / 37 signals
•
July 2004
•
“The best frameworks are in my
opinion extracted, not envisioned.
And the best way to extract is first
to actually do.”

4. STUFF ON RAILS

5. ECOSYSTEM
RubyGems

6. PACKAGES
ASP.NET NuGet:
PHP
Pear:
Packagist/Composer:
Python PyPI:
Node.JS NPM:
Ruby RubyGems:
17,770
!
595
21,754
38,607
53,740
68,500
!
Honorable mention:
Java, Scala: Maven etc, too many to count

7. INTERACTIVE CONSOLE

8. MANY WAYS TO DO IT
n = 15!
!
(1..n).each do |i|!
n_zvezdic = (i - 1) * 2 + 1!
n_presledkov = n - i!
!
(1..n_presledkov).each do!
putc " "!
end!
!
(1..n_zvezdic).each do!
putc "*"!
end!
!
putc "n"!
end!
!

9. MANY WAYS TO DO IT
n = 15!
!
(1..n).each do |i|!
n_zvezdic = (i - 1) * 2 + 1!
n_presledkov = n - i!
!
n_presledkov.times do!
print " "!
end!
!
n_zvezdic.times do!
print "*"!
end!
!
print "n"!
end!
!

10. MANY WAYS TO DO IT
n = 15!
!
(1..n).each do |i|!
n_zvezdic = (i - 1) * 2 + 1!
n_presledkov = n - i!
!
print " " * n_presledkov!
!
!
!
print "*" * n_zvezdic!
!
!
!
print "n"!
end!
!

11. MANY WAYS TO DO IT
n = 15!
!
(1..n).each do |i|!
n_zvezdic = (i - 1) * 2 + 1!
n_presledkov = n - i!
!
puts " " * n_presledkov + "*" * n_zvezdic!
!
!
!
!
!
!
!
!
end!
!

12. MANY WAYS TO DO IT
n = 15!
!
n.times do |i|!
n_zvezdic = i * 2 + 1!
n_presledkov = n - i - 1!
!
puts " " * n_presledkov + "*" * n_zvezdic!
end!
!
!
!
!
!
!
!
!
!

13. MANY WAYS TO DO IT
n = 15!
!
n.times{|i| puts " "*(n-i-1) + "*"*(i*2+1)}!
!
!
!
!
!
!
!
!
!

14. MANY WAYS TO DO IT
n = 15!
!
(1..n).each do |i|!
n_zvezdic = (i - 1) * 2 + 1!
n_presledkov = n - i!
!
(1..n_presledkov).each do!
putc " "!
end!
!
(1..n_zvezdic).each do!
putc "*"!
end!
!
putc "n"!
end!
!

15. MANY WAYS TO DO IT
n = 15!
!
n.times{|i| puts " "*(n-i-1) + "*"*(i*2+1)}!
!
!
!
!
!
!
!
!
!

16. MANY WAYS TO DO IT
n = 15!
!
n.times{|i| puts " "*(n-i-1) + "*"*(i*2+1)}!
!
Java:!
class Test { public static void main(String args[]) {} }!
!
!
!
!
!
!
!

17. MANY WAYS TO DO IT
n = 15!
!
n.times{|i| puts " "*(n-i-1) + "*"*(i*2+1)}!
!
!
!
!
!
!
!
!
!

18. JUST COOL
Date.today.thursday? # => true!
!
10.seconds.ago # => 2014-01-09 09:15:10 +0100!
!
10.even? # => true!
!
102.megabytes + 24.kilobytes + 10.bytes # => 106,979,338!
!
10 + 1 # => 11!
!
class Fixnum!
def +(i)!
42!
end!
end!
!
10 + 1 # => 42!

19. JUST COOL
def alive?!
state != :dead!
end!
!
def clear!!
everything.remove!
end!
!
def setting=(value)!
raise "invalid value" unless value == 42!
end!
obj.setting = 5!
!
def [](key)!
key + 1!
end!
obj[1] # => 2!
!
def []=(key, value)!
whatevz!
end!
obj[1] = 2!

20. BEST PRACTICES
Short methods, self-commenting code
+ readability
+ testing
!
You only need comments when you know your code
is written so bad that people won’t understand it.

21. def clients!
User.where(user_type: "client")!
end!
!
def days_until_next_week(date)!
8 - date.cwday!
end!
!
def next_week_start(after_date)!
after_date + days_until_next_week(after_date).days!
end!
def payments_next_week!
payments = []!
!
User.where(user_type: "client").each do |user|!
next_week_start = Date.today + (8 Date.today.cwday).days!
next_week_end = next_week_start + 7.days!
payments = user.payments.where("due_on >= ? AND
due_on < 1.week.from_now", next_week_start,
next_week_end)!
payments.each do |payment|!
next if payment.due_on.saturday? ||
payment.due_on.sunday?!
payments << payment!
end!
end!
end!
!
def week_end(week_start)!
week_start + 7.days!
end!
!
def client_payments_between(client, range)!
client.payments!
.where("due_on >= ?", range.first)!
.where("due_on < ?", range.last)!
end!
!
def client_payments_next_week(client)!
start_day = next_week_start(Date.today)!
client_payments_between(client,!
start_day..week_end(start_day))!
end!
!
def payment_on_weekend?(payment)!
payment.due_on.saturday? || payment.due_on.sunday?!
end!
!
def payments_next_week!
clients.flat_map do |client|!
client_payments_next_week(client).reject do |payment|!
payment_on_weekend?(payment)!
end!
end!
end!

22. BEST PRACTICES
Testing
!
!
!
!
describe "#decline!" do!
subject { create :booking }!
context "without reason" do!
before { subject.decline! }!
its(:status) { should == "declined" }!
its(:declined?) { should be_true }!
end!
context "with reason" do!
before { subject.decline!("REASON!") }!
its(:status) { should == "declined" }!
its(:declined?) { should be_true }!
its(:status_reason) { should == "REASON!" }!
end!
end!

23. BEST PRACTICES
TEST FIRST => great object interfaces/APIs
Write how you want to use it, before you implement it.

24. BEST PRACTICES
Don’t repeat yourself!
Extract duplicate logic
# user.rb!
!
# file1.rb!
!
User.where(user_type:
!
# file2.rb!
!
"client").first!
User.where(user_type: "client", active: false).first!
class User!
def self.client!
where(user_type: "client")!
end!
end!
!
# file1.rb!
!
User.client.first!
!
# file2.rb!
!
User.client.where(active: false).first!

25. BEST PRACTICES
Don’t repeat yourself!
Extract duplicate logic
# user.rb!
!
class User!
def self.client!
where(user_type: "client")!
end!
end!
# file1.rb!
!
User.where(user_type:
!
# file2.rb!
!
"client").first!
!
# file1.rb!
User.where(user_type: "client", active: false).first!
!
User.client.first!
!
# file2.rb!
2 places to fix
1 place to fix
!
User.client.where(active: false).first!
+ easier to test

26. BEST PRACTICES
Convention over configuration
Sensible defaults

27. MY STUFF

32. MY JOB STUFF @ D-LABS

36. QUESTIONS