RAILS IS FROM MARSRUBY 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.

YOU KNOW RAILS

insert logohere

:(

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 GUIDEIt has cartoon foxes. Foxen? It has cartoon foxen.

PROGRAMMING RUBYa.k.a. The Pickaxe

MR. NEIGHBORLY’S HUMBLE LITTLE

RUBY BOOKPragmatically 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 OPINIONSAnd Ruby Likes To Talk

Rails is opinionated software

Ruby is a communicative language

Sometimes, Ruby just wantssomeone 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 YOUBut Sometimes You Drive Her Crazy

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

You’re welcome.

# Badi = 0; while i < array.size do puts array[i] i += 1end

# Betterfor item in array puts itemend

# Bestarray.each do |item| puts itemend

WHY?

• Ruby has powerful iterators.

• You don’t need to write your own.

• for ... in ... just calls #each internally.

# Badvalue = value ? value : "default"

# Bettervalue = value || "default"

# Bestvalue ||= "default"

WHY?

• Ternaries (the ? : thing) are ugly.

• Ruby has pretty assignment with operators like += and ||=

# Badarray << 42 unless array.include?(42)array = array + [42] unless array.include?(42)

# Betterarray = array | [42]

# Bestarray |= [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

• Writing your own coercion method can help you use Ruby’s ducktyping.

• Separation of concerns.

RAILS PERFORMANCEInsert your “scaling” and “premature optimization” jokes here.

Yes, I went there.

Slow is only meaningfulin 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.