RailsConf 2011 Keynote

Before I Begin...

Wednesday, May 18, 2011

@jonleighton


I José

Double Dream Hands:
SO INTENSE


ZOMG!!!

Aaron Patterson


@tenderlove


AT&T, AT&T logo and all AT&T related marks are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies.

WWFMD?

Richard Gabriel Guy Steele DHH
Researcher Software Architect Partner


Aaron Batalion Chad Dickerson Dan Melton
CTO CTO CTO


Aaron Patterson
Corey Haines Eric Ries
Señor Software
Corey Haines Venture Advisor
Engineer


LOLWUT


Señor Software Engineer

Agenda


Agenda

New Features

Real Talk!

Development Pro Tips™

Implementation
and thoughts on
API design

I will be very
TECHNICAL


Because my
audience is
smart

I will be very
CRITICAL
Because I care


New Features!


git log --since="1 year ago"


API Strategy


rails generate VC


def halts?(function)


Prepared
Statements


select * from 'users'
where id = 10


select * from 'users'
where id = ?


DATABASE

RAILS APP

DATABASE

Records
RAILS APP

4 Steps!


DATABASE

Token
RAILS APP

2 Steps!


Impact


SQLite3


SQLite3 Simple Prepared Statement
100.00

10.00
y = 8.556E-5e2.2868x
y = 0.0002e2.187x
1.00

0.10

0.01

0.00

0.00
10 100 1000 10000 100000

Number of Queries
Cached Trend 1
Non-Cached Trend 2

8665 q/s
12987 q/s


Δ 4322 q/s


SQLite3 Complex SQL Statement
1000

100
y = 0.0003e2.2227x
y = 0.0029e2.3111x
10

1

0

0

0
10 100 1000 10000 100000
Cached Trend 1 Number of Queries
Non-Cached Trend 2

339 q/s
4184 q/s


Δ 3845 q/s


PostgreSQL


PostgreSQL Simple Query
100.0
y = 0.0002e2.3018x
y = 0.0004e2.1424x
10.0

1.0

0.1

0.0

0.0
10 100 1000 10000 100000
Cached Trend 1 Queries
No Cache Trend 2

4662 q/s
5586 q/s


Δ 924 q/s


PostgreSQL Complex Query
1000

y = 0.0005e2.173x
100
y = 0.0047e2.2153x

10

1

0

0

0
10 100 1000 10000 100000
Queries
Cached Trend 1
No Cache Trend 2

307 q/s
3322 q/s


Δ 3015 q/s


MySQL


MySQL Simple Query
100

10

1

0

0

0
10 100 1000 10000 100000
Cache No Cache Queries


6410 q/s
5154 q/s


Δ -1256 q/s


MySQL Complex SQL Query
1000

100

10

1

0

0

0
10 100 1000 10000 100000
Cached Category Title
No Cache

626 q/s
1198 q/s


Δ 572 q/s


No Query
Planning


Two Network
Roundtrips


Problem?

select updated_at from
pirates

[[#<Mysql::Time:2011-05-13 22:03:55>]]

[["2011-05-13 22:03:55"]]


pirates
Prepared Statement

[[#<Mysql::Time:2011-05-13 22:03:55>]]

[["2011-05-13 22:03:55"]]


pirates

[[#<Mysql::Time:2011-05-13 22:03:55>]]

Regular Statement

[["2011-05-13 22:03:55"]]


API Changes


User.ﬁnd 1


Serialized
Attributes


class User < ActiveRecord::Base
serialize :preferences
end


Saves as YAML

user = User.find 1
user.preferences = { :hello => 'world!' }
user.save!


Why YAML?


serialize :preferences, Base64Encoder.new
end


Base 64 Storage
class Base64Encoder
def load(value)
return unless value
value.unpack('m').last
end

def dump(text)
[text].pack('m')
end
end


JSON Storage
class JSONEncoder
def load(value)
return unless value
JSON.load value
end

def dump(text)
JSON.dump(text)
end
end


Marshal Storage
class MarshalEncoder
def load(value)
return unless value
Marshal.load value
end

def dump(text)
Marshal.dump(text)
end
end


XML Storage
class XMLEncoder
def load(value)
return unless value
Nokogiri.XML value
end

def dump(doc)
doc.to_xml
end
end


Ofﬁcial NoSQL
Support


IT'S
OFFI
CIAL

Ofﬁcial NoSQL
!

Support


2 Caveats


PostgreSQL Only


You might hurt
yourself


DO NOT DO THIS
class HStore
def load value
return unless value
eval "{#{value}}"
end

def dump value
return unless value
value.map { |xs| xs.join '=>' }.join ', '
end
end

serialize :preferences, HStore.new
end

BCrypt Coder
class BCryptCoder
def load(value)
return unless value
BCrypt::Password.new value
end

def dump(value)
BCrypt::Password.create(value).to_s
end
end


BCrypt Serialization

serialize :crazy_column, BCryptCoder.new
end


stdlib serialization API
Dumping Loading

YAML dump load

JSON dump load

Marshal dump load


Storage type

YOU choose
Column name


Good Abstractions
yield
Good Features

CONSISTENCY
is FREEDOM
and FLEXIBILITY

has_secure_password


SECURITY!

has_secure_password
end


SECURITY!

user = User.find 1
user.password = 'lolwut'
user.save!


Advantages

Introduces a new method
Saves password in `password_digest`
Uses BCrypt


Disadvantages
API is not flexible

Introduces a new method
Saves password in `password_digest`
Not
Uses BCrypt reusable


GO GREEN!


Write Something
REUSABLE!


response
streaming

Streaming chunked
encoding

Responses


Rack API

class MyApp
def call(env)
[200, { 'X-ZOMG' => 'hi' }, ['web page!']]
end
end


Rails 3.0.x

class PoniesController
def call(env)
body << render(:content)
body << render(:layout)

[200, {}, body]
end
end


Delayed
Evaluation


Body#each


Rails 3.1.x
class DelayedBody
def each
yield render(:layout)
yield render(:content)
end
end

class PoniesController
def call(env)
[200, {}, DelayedBody.new]
end
end

Middleware


Middleware ☹

Middleware Chain
Just consider
connection
Request Timer manager and
application

Connection Manager

Application


Middleware Chain

Connection Manager

Application


Middleware Chain
call(env)

Connection Manager

call(env)

Application


Middleware Chain
[200, {}, body]

Connection Manager

[200, {}, body]

Application


Connection Manager
When ERb is evaluated,
db connection does not
exist


Connection Manager
Open DB Connection When ERb is evaluated,
exist


Connection Manager
exist
Delegate


Connection Manager
exist
Delegate

Close DB Connection


Connection Manager
exist
Delegate

Close DB Connection

Return Delegate Values


Body#close


Body Proxy
class ConnectionBodyProxy
def initialize(delegate)
@delegate = delegate
end
def each(&blk)
@delegate.each(&blk)
end
def close
# CLOSE CONNECTION
end
end

Connection Manager
class ConnectionManager
def initialize(app); @app = app; end

def call(env)
# OPEN CONNECTION
response = @app.call(env)
response[2] = ConnectionBodyProxy.new(response[2])
response
end
end


~25 middleware


Embrace
Diversity


Types of Middleware

Generators (our application)
Filters (gzip, etc)
Lifecycle Handlers (connection management)


Real Talk!


Rails is getting
slower


Time for N Requests
Rails 2.3 Rails 3.0
100

10

1

0.1

0.01
10 100 1000 10000
Requests

Avg Requests / time
Rails 2.3 Rails 3.0
500

387.5

275

162.5

50
10 100 1000 10000
Requests

Middleware
Increased


/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
Total samples: 740 Rack
garbage_collector Object#require Object#map
ActiveRecord
ConnectionAdapters
Focusing on: 740 Runtime#call
0 (0.0%) 27 (3.6%) 165 0 (0.0%) SQLiteAdapter#execute

146 (19.7%)
of 57 (7.7%) 1 (0.1%)
of 463 (62.6%)

Dropped nodes with <= 3 abs(samples) of 128 (17.3%) of 56 (7.6%)

Dropped edges with <= 0 samples
463 118 74 62

Rails
Rack
Kernel#require Rails30
Application.method_missing
Logger#call
0 (0.0%)
28 (3.8%) 60 0 (0.0%)
of 62 (8.4%)
of 463 (62.6%)
of 63 (8.5%)

381 80 62

ActionDispatch Rails
ShowExceptions#call Application#initialize!
0 (0.0%) 0 (0.0%)
of 381 (51.5%) of 62 (8.4%)

Rails
Rack
381 Logger#after_dispatch
0 (0.0%)
62 17
of 80 (10.8%)

ActionDispatch
Object#run_initializers
RemoteIp#call
0 (0.0%) 80 0 (0.0%)
of 62 (8.4%)
60
of 382 (51.6%)

ActiveSupport
LogSubscriber.ﬂush_all!
382 0 (0.0%) 60
of 80 (10.8%)

Rails
Rack
Initializable
Sendﬁle#call
Initializer#run
0 (0.0%)
0 (0.0%)
of 383 (51.8%)
of 60 (8.1%)

383 60

ActionDispatch
Object#instance_exec
Callbacks#call
2 (0.3%)
2 (0.3%)
of 60 (8.1%)
of 383 (51.8%)

381 381 381

ActiveRecord
ActionDispatch
ConnectionAdapters
Callbacks#_run_call_callbacks
ConnectionManagement#call
0 (0.0%)
0 (0.0%)
of 381 (51.5%)
of 381 (51.5%)

375

ActiveRecord
QueryCache#call
2 (0.3%)
of 377 (50.9%)

372 375
ActionDispatch

230 230 230 219 219

ActionController Benchmark.ms ActionController
Metal#cleanup_view_runtime Metal#render_to_string
0 (0.0%) 230 10 (1.4%) 0 (0.0%)
of 230 (31.1%) of 230 (31.1%) of 219 (29.6%)

219 220 213

ActionController
Benchmark.realtime Metal#render_to_body
0 (0.0%)
of 220 (29.7%) 2 (0.3%) 424
of 213 (28.8%)

210

ActionController
Metal#_render_template
0 (0.0%)
of 210 (28.4%)

190

ActiveSupport
Object#render
Notifications.instrument
0 (0.0%)
0 (0.0%)
of 190 (25.7%)
of 322 (43.5%)

487 507 175 185 189

ActiveSupport
Notifications Object#_render_template
167 Instrumenter#instrument
0 (0.0%)
2 (0.3%) 167
of 322 (43.5%)
of 189 (25.5%)

18

ActionView
Template#render
2 (0.3%)
of 167 (22.6%)

148 155

Object#_app_views_layouts_application_html_erb___604422253_2164033400_0
0 (0.0%)
of 148 (20.0%)
149

85 58 1

Object#stylesheet_link_tag Object#javascript_include_tag Object#_render_layout
0 (0.0%) 3 (0.4%) 6 (0.8%)
of 85 (11.5%)
of 58 (7.8%) of 155 (20.9%)

83

Object#expand_stylesheet_sources
0 (0.0%)
of 83 (11.2%)

81

Object#collect_asset_files
81 (10.9%)

work/Versions/1.8/usr/bin/ruby
Rack
Runtime#call
0 (0.0%)
garbage_collector Object#require
27 (3.6%) 165
Object#map
0 (0.0%)
ActiveRecord
ConnectionAdapters
SQLiteAdapter#execute

146 (19.7%)
of 57 (7.7%) 1 (0.1%)
of 463 (62.6%)
of 128 (17.3%) of 56 (7.6%)

463 118 74 62

Rails
Rack
Kernel#require Rails30
Application.method_missing
Logger#call
0 (0.0%)
28 (3.8%) 60 0 (0.0%)
of 62 (8.4%)
of 463 (62.6%)
of 63 (8.5%)

381 80 62

ActionDispatch Rails
ShowExceptions#call Application#initialize!
0 (0.0%) 0 (0.0%)
of 381 (51.5%) of 62 (8.4%)

Rails
Rack
381 Logger#after_dispatch
0 (0.0%)
62 17
of 80 (10.8%)

ActionDispatch
Object#run_initializers
RemoteIp#call
Wednesday, May 18, 2011 0 (0.0%) 80 0 (0.0%) 60

GC Pressure


Stack Depth
Rails 2.3 Rails 3.0 Rails 3.1

70

52.5

35

17.5

0
Stack Depth


Rails 2.3 Stack


51 deep


Rails 3.0 Stack


60 deep


Rails 3.1 Stack


67 deep


/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/implicit_render.rb:5:in `send_action'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/base.rb:150:in `process_action'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/rendering.rb:11:in `process_action'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/callbacks.rb:18:in `process_action'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:436:in `_run__84203013__process_action__199225275__callbacks'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:410:in `send'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:410:in `_run_process_action_callbacks'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:94:in `run_callbacks'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/instrumentation.rb:30:in `process_action'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/notifications.rb:52:in ìnstrument'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/notifications/instrumenter.rb:21:in ìnstrument'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/rescue.rb:17:in `process_action'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/base.rb:119:in `process'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/rendering.rb:41:in `process'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal.rb:138:in `dispatch'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal.rb:178:in àction'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/routing/route_set.rb:62:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
/Library/Ruby/Gems/1.8/gems/rack-mount-0.6.14/lib/rack/mount/route_set.rb:148:in `call'
/Library/Ruby/Gems/1.8/gems/rack-mount-0.6.14/lib/rack/mount/code_generation.rb:93:in `recognize'
/Library/Ruby/Gems/1.8/gems/rack-mount-0.6.14/lib/rack/mount/code_generation.rb:68:in òptimized_each'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/head.rb:14:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/methodoverride.rb:24:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/params_parser.rb:21:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/flash.rb:182:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/cookies.rb:302:in `call'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/query_cache.rb:32:in `call'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/query_cache.rb:12:in `cache'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:354:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/callbacks.rb:46:in `call'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:416:in `_run_call_callbacks'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/sendfile.rb:107:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
/Library/Ruby/Gems/1.8/gems/railties-3.0.7/lib/rails/rack/logger.rb:13:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/runtime.rb:17:in `call'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/cache/strategy/local_cache.rb:72:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/lock.rb:11:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/lock.rb:11:in `synchronize'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/static.rb:30:in `call'
/Library/Ruby/Gems/1.8/gems/railties-3.0.7/lib/rails/application.rb:168:in `call'
fuuu.rb:44
fuuu.rb:43:in `times'
fuuu.rb:43


/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/base.rb:150:in `process_action'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/rendering.rb:11:in `process_action'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:436:in `_run__84203013__process_action__199225275__callbacks'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:410:in `_run_process_action_callbacks'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:94:in `run_callbacks'

TL;DR
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/notifications/instrumenter.rb:21:in ìnstrument'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/rescue.rb:17:in `process_action'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/base.rb:119:in `process'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/abstract_controller/rendering.rb:41:in `process'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal.rb:138:in `dispatch'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_controller/metal.rb:178:in àction'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
/Library/Ruby/Gems/1.8/gems/rack-mount-0.6.14/lib/rack/mount/code_generation.rb:68:in òptimized_each'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/head.rb:14:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/methodoverride.rb:24:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/params_parser.rb:21:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/flash.rb:182:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/cookies.rb:302:in `call'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/query_cache.rb:12:in `cache'
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/connection_pool.rb:354:in `call'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/callbacks.rb:416:in `_run_call_callbacks'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/sendfile.rb:107:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
/Library/Ruby/Gems/1.8/gems/railties-3.0.7/lib/rails/rack/logger.rb:13:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/runtime.rb:17:in `call'
/Library/Ruby/Gems/1.8/gems/activesupport-3.0.7/lib/active_support/cache/strategy/local_cache.rb:72:in `call'
/Library/Ruby/Gems/1.8/gems/rack-1.2.2/lib/rack/lock.rb:11:in `synchronize'
/Library/Ruby/Gems/1.8/gems/actionpack-3.0.7/lib/action_dispatch/middleware/static.rb:30:in `call'
/Library/Ruby/Gems/1.8/gems/railties-3.0.7/lib/rails/application.rb:168:in `call'
fuuu.rb:44
fuuu.rb:43:in `times'
fuuu.rb:43


We need a
change


Generators
class Application
def call(request, response)
response.write(request, "hello", 200, {})

10.times do |body|
response.write(request, body)
end

response.close
end
end

Filters
class Filter
def initialize(filter)
@filter = filter
end

def write(request, body, status = nil, headers = nil)
@filter.write(request, body, status, headers)
end

def close
@filter.close
end
end

Lifecycle Hooks

class Handler
def before(request)
# Connect to database
end

def after(request)
# Disconnect
end
end


Stack Depth
Rails 2.3 Rails 3.0 Rails 3.1 Rails 3.2?

70

52.5

35

17.5

0
Stack Depth


Time for N Requests
Rails 2.3 Rails 3.0 Rails 3.2?
100

10

1

0.1

0.01
10 100 1000 10000
Requests

Avg Requests / time
Rails 2.3 Rails 3.0 Rails 3.2?
650

500

350

200

50
10 100 1000 10000
Requests

git log --until="1 year from now"


Important
things to
me

We Must Change


Speed


Memory


Stack Depth


Backwards
Compat


Development
Pro Tip™


Final Words


We will not Rails will
be here
forever outlive us

A Message for Encourage
refactoring

Stop "yes

Rails-Core
men"


Not all features
are Tangible


Good Abstraction
yield
Reusable Code

Reusable Code
yield
New Features

Your Homework:


Refactor Rails!


GO FORTH AND
CODE!


THANKS!


QUESTIONS?


RailsConf 2011 Keynote

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RailsConf 2011 Keynote