RAILS IS FROM MARS
RUBY IS FROM VENUS
Relationship Advice For Rails Developers

WHO AM I?
• My name is Rein Henrichs.
• That’s pronounced like “rain”.
• But spelled differently.
•I work at
•I blog at reinh.com
•I twitter @reinh
•I like candlelit dinners and long walks on the beach.

insert logo
here
:(
YOU KNOW RAILS

BUT DO YOU KNOW RUBY?

How many people here use Rails?

How many of you think you know
Ruby as well as you know Rails?

How many of you have
contributed to an open-source
Ruby project?

How many of you have
written your own gem?

How many of you would be
comfortable writing an HTTP
client library in Ruby?

How many of you could write
your own web framework?

WHY SHOULD I LEARN RUBY?
• It’s easy.
• It’s fun.
• It will make you better at Rails.
• It will make you a better person.

HOW DO I LEARN RUBY?
Some resources

Free stuff

WHY’S POIGNANT GUIDE
It has cartoon foxes. Foxen? It has cartoon foxen.

PROGRAMMING RUBY
a.k.a. The Pickaxe

MR. NEIGHBORLY’S
HUMBLE LITTLE
RUBY BOOK
Pragmatically chunky bacon

Not so free stuff
(but still really good)

RUBY IN A
NUTSHELL
Come on. Matz wrote it.

RUBY IN
PRACTICE
Look at that funny looking guy
on the cover. At least it’s not a
nasty monkey. Sorry, O’Reilly

THE RUBY
WAY

RUBY FOR
RAILS

THE WELL-
GROUNDED
RUBYIST

RAILS HAS OPINIONS
And Ruby Likes To Talk

Rails is opinionated software

Ruby is a communicative language

Sometimes, Ruby just wants
someone to listen to it.

If you’re programming along, doing nicely, and
all of a sudden your program gets balky, makes
things hard for you, it’s talking. It’s telling you
there is something important missing.
– Kent Beck, Smalltalk Best Practice Patterns

It is your responsibility to
listen to your code and be
considerate of its needs.

Write Ruby code that
communicates well but be
respectful of Rails’ opinions

Other people who use your code
(including six-months-later you)
will thank you.

Ruby makes it easy to write
simply, clearly and expressively

Rails has powerful idioms
and conventions

Combining the two makes for a
happy, fulfilling relationship

RUBY LOVES YOU
But Sometimes You Drive Her Crazy

These are some of the things you
do that drive Ruby crazy.

You’re welcome.

# Bad
i = 0; while i < array.size do
puts array[i]
i += 1
end
# Better
for item in array
puts item
end
# Best
array.each do |item|
puts item
end

WHY?
• Ruby has powerful iterators.
• You don’t need to write your own.
... in ... just calls #each internally.
• for

# Bad
value = value ? value : \"default\"
# Better
value = value || \"default\"
# Best
value ||= \"default\"

WHY?
• Ternaries (the ? : thing) are ugly.
• Ruby has pretty assignment with operators like += and ||=

# Bad
array << 42 unless array.include?(42)
array = array + [42] unless array.include?(42)
# Better
array = array | [42]
# Best
array |= [42]

WHY?
• Sometimes it just helps to know what set union is.

# Bad
if value != nil && value != false
# Good
if value

WHY?
• Ruby has a sane notion of truthiness

# Bad
if value == 1 || value == 12 || value == 42
# Good
if [1,12,42].include? value

WHY?
• Brevity is not the goal
• Readability is the goal
• But if it is more readable and also shorter, go for it.

# Bad
def request
begin
perform_request
rescue RequestError => e
log_error e
end
end
# Good
def request
perform_request
rescue RequestError => e
log_error e
end

WHY?
• Method definitions are an implied begin block.

# Bad
!!value
# Good
value

WHY?
• Ruby does not not like clarity.
• What you lose in readability you gain in nothing.

# Bad
ActiveRecord::Base
# Good
ActiveRecord::Model

WHY?
• Naming things is important.
• Base? What does that even mean?
• Sorry Rails, you got this one wrong. Better luck next time.

# Bad
class PostsController < ApplicationController
def recent
Post.find :all,
:conditions => ['posts.created_at > ?',
1.week.ago]
end
end

# Good
class PostsController < ApplicationController
def recent
Post.within 1.week
end
end

class Post < ActiveRecord::Base
named_scope :within,
lambda {|seconds| :conditions => ['posts.created_at > ?',
seconds.ago]}
end

WHY?
• Make your code more expressive
• And more intention revealing.
• In other words, say what you mean to say.

url_for(:blog, :posts, @post.id, :comments, :replies => true)
# => http://example.com/blog/posts/19/comments?replies=true

# Bad
def url_for(*args)
root + args.map{|arg| parse_arg(arg)}.join('/').
gsub('/?', '?')
end
def parse_arg(arg)
case arg
when Array: arg.join('/')
when Hash
ret = []
each{|k,v| ret << \"#{k}=#{v}\"}
ret = ret.join('&')
'?' + ret
else: arg.to_s
end
end

# Good
def url_for(*args)
root + args.to_params
end

class Array
def to_params
map{|a| a.to_params}.join('/').
gsub('/?', '?')
end
end

# Array
%w(foo bar bazz).to_params # \"/foo/bar/bazz\"
# Hash
{:foo => :bar}.to_params # \"?foo=bar\"

WHY?
• Ruby uses coercion in many places
• 1.to_s
• (1..10).to_a
• Writingyour own coercion method can help you use Ruby’s
ducktyping.
• Separation of concerns.

RAILS PERFORMANCE
Insert your “scaling” and “premature optimization” jokes here.

Yes, I went there.

Slow is only meaningful
in comparison.

Ruby is slow? Compared to what?

Is your database slow?

Are your views slow?

Is your app server slow?

Are you using HTTP
via carrier pigeon?

If you don’t know where the slow
is, you’re not ready to optimize.

Don’t optimize prematurely, but
don’t pessimize either.

Don’t write code you know will
never, ever be fast.

# Really Bad (Optimally Pessimum)
class Ballot < ActiveRecord::Base
def <=>(other)
votes.count <=> other.votes.count
end
end
# Good (Potentially Optimum)
class Ballot < ActiveRecord::Base
# With a counter_cache on votes
default_scope :order => :votes_count
end

IN OTHER WORDS
• Don’t worry about speed until you know where the slow is.
• Worry about writing simply and expressively.
• Well written code is easy to optimize for performance later.
• Don’t write something you know will never, ever be fast.

IN CONCLUSION
• Ruby is fun and easy (and friendly!).
• Ruby will make you happy.
• Be more thoughtful in the way you treat Ruby.
• The more Ruby you know, the better you can become at Rails.
• If you love Rails, you should love Ruby too.
• Also, don’t be premature. No one likes that.

WHO AM I?
• My name is Rein Henrichs.
• That’s pronounced like “rain”.
• But spelled differently.
•I work at
•I blog at reinh.com
•I twitter @reinh
•I like candlelit dinners and long walks on the beach.