Code to Joy

Code to Joy
Avdi Grimm
ShipRise
GoGaRuCo 2012
Avdi Grimm (ShipRise) Code to Joy GoGaRuCo 2012 1 / 50

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Code to Joy Introduction
Introduction
These are a few of my favorite things.
Avdi Grimm (ShipRise) GoGaRuCo 2012 2 / 50

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My Job is Awesome
• My job is awesome

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My Job is Awesome
• Remotely pairing with many different people

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My Job is Awesome
• Different levels of knowledge, different problems to solve

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My Job is Awesome
• Different levels of knowledge, different problems to solve
• ”That’s so cool, I didn’t know you could do that”

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Ruby is Awesome
Ruby is designed to make programmers happy.
— Matz
It still ﬁnds ways to make me smile after all these years.

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Postcards are Awesome
• Work in progress: Conﬁdent Ruby

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• ”Pay with a postcard”

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• ”Pay with a postcard”
• Postcards make me happy!

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The Plan
• A random walk through the Ruby language and standard
library. . .

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The Plan
library. . .
• . . . stopping in at some of my favorite idioms and tools. . .

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The Plan
library. . .
• . . . stopping in at some of my favorite idioms and tools. . .
• . . . and around the world, in postcards!

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Code to Joy Splats
Splats

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Code to Joy Splats
Simple Destructuring
spawn( ’true’ )
pid, status = *Process.wait2
pid # => 9159
status # => #

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Code to Joy Splats
Implicit splat
spawn( ’true’ )
pid, status = Process.wait2
pid # => 16804
status # => #

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Code to Joy Splats
Multiple return values
def send_request
# ...
code = 404
message = "Not found"
# ???
end

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Code to Joy Splats
One client wants individual values
code, message = send_request
logger.info " #{ code } : #{ message } "

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Code to Joy Splats
Another client wants an object
response = send_request
case response.code
when 400..599 then handle_error(response)
else
# ...
end

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Code to Joy Splats
cake.have && cake.eat
Response = Struct.new( :code , :message )
r = Response.new(404, "Not found" )
# Attributes:
r.code # => 404
r.message # => "Not found"
# Splat:
code, msg = *r
code # => 404
msg # => "Not found"

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Code to Joy Splats
One little problem
Response = Struct.new( :code , :message )
code, msg = r # no splat
code # => #
msg # => nil

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Code to Joy Splats
An implicitly splattable Struct
Response = Struct.new( :code , :message ) do
alias_method :to_ary , :to_a
end

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Code to Joy Splats
An implicitly splattable Struct
Response = Struct.new( :code , :message ) do
alias_method :to_ary , :to_a
end
code, msg = r # look ma, no splat!
code # => 404
msg # => "Not found"

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Code to Joy Splats
Returning a splattable Struct
def send_request
# ...
Response.new(code, message)
end

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Code to Joy Splats
Splatting the Struct into component parts
code, message = send_request
logger.info " #{ code } : #{ message } "

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Code to Joy Splats
Using the response Struct as-is
response = send_request
case response.code
when 400..599 then handle_error(response)
else
# ...
end

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Code to Joy Splats
Splats & Structs
• Return multiple values from a method. . .
• . . . *Or* a single result object. . .
• . . . from the same line of code. Magic!

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Code to Joy YAML::Store
YAML::Store

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Persisting Posts
require ’yaml/store’
repo = YAML::Store.new( ’blog.yml’ )
Post = Struct.new( :title , :body )
repo.transaction do
posts = repo[ :posts ] = []
posts << Post.new( "F1rst Post!!!" , "FIRST" )
posts << Post.new( "Hiatus" ,
"This blog is on vacation" )
end

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The Persisted Data
cat blog.yml
---
:posts:
- !ruby/struct:Post
title: F1rst Post!!!
body: FIRST
- !ruby/struct:Post
title: Hiatus
body: This blog is on vacation

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Associations
Post = Struct.new( :title , :body , :category )
Category = Struct.new( :name )
food = Category.new( :food )
repo.transaction do
posts = repo[ :posts ] = []
posts << Post.new( "Cookie!!!" ,
"C is for cookie!" , food)
posts << Post.new( "Durian" ,
"Stinky!" , food)
end

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Associations YAML
---
:posts:
- !ruby/struct:Post
title: Cookie!!!
body: C is for cookie!
category: &8509480 !ruby/struct:Category
name: :food
- !ruby/struct:Post
title: Durian
body: Stinky!
category: *8509480

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PStore
• Drop-in replacement
require ’pstore’
2
repo = PStore.new( ’blog.pstore’ )
repo.transaction do
4
# ...
end

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PStore
• Drop-in replacement
require ’pstore’
2
repo = PStore.new( ’blog.pstore’ )
repo.transaction do
4
# ...
end
• Faster
Adding 1000 posts, with a transaction for each write:
user system total real
yaml 50.210000 0.210000 50.420000 ( 54.024277)
pstore 3.290000 0.130000 3.420000 ( 10.887887)

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YAML#Store
• Incredibly simple Hash-like persistence mechanism
• Great for local command-line apps
• Supports complex object trees
• Oh yeah, one more thing. . .

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YAML#Store
• Incredibly simple Hash-like persistence mechanism
• Great for local command-line apps
• Supports complex object trees
• Oh yeah, one more thing. . .
• ZOMG NOSQL!!!

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Code to Joy Enumerators
Enumerators

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Kernel#to_enum
Convert any old method into an Enumerator
def names
yield ’Ylva’
yield ’Brighid’
yield ’Shifra’
yield ’Yasmin’
end
e = to_enum( :names ) # => #
e.to_a # => ["Ylva", "Brighid", "Shifra", "Yasmin"]

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Pathname#ascend
require ’pathname’
Dir.chdir( ’/home/avdi/dev’ )
Pathname.pwd.ascend do |dir|
puts dir
end
/home/avdi/dev
/home/avdi
/home
/

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Searching upwards for conﬁg ﬁles
require ’pathname’
curdir = Pathname.pwd
configs = curdir.to_enum( :ascend ).
each_with_object([]){ |dir, files|
config = (dir + ’.rutrc’ )
files << config if config.file?
}

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Searching upwards for conﬁg ﬁles
curdir = Pathname.pwd
configs = curdir.to_enum(:ascend).
each_with_object([]) { |dir, files|
config = (dir + ’.rutrc’)
files « config if config.file?
}

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Enumerator and #to_enum
• Turn any method into an iterable series
• Make all the power of Enumerator available to the series

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Code to Joy Break
Give me a break

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Code to Joy Break
break
It breaks out of loops. Whoop-de-doo.
jobs.each do |job|
break if job == :terminate
job.call
end

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Code to Joy Break
break beyond iteration
def names
yield ’Ylva’
yield ’Brighid’
yield ’Shifra’
yield ’Yasmin’
end

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Code to Joy Break
i = 0
names do |name|
puts name
break if i >= 1 # that’s plenty!
i += 1
end
Ylva
Brighid

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Code to Joy Break
def names
yield ’Ylva’
yield ’Brighid’
# ---- We stopped here! ----
yield ’Shifra’
yield ’Yasmin’
end
Without a return, throw, or raise.

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Code to Joy Break
break respects ensure blocks
def names_with_last
yield ’Ylva’
yield ’Brighid’
yield ’Shifra’
yield ’Yasmin’
ensure
puts "Grimm"
end

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Code to Joy Break
i = 0
names_with_last do |name|
puts name
break if i >= 1 # that’s plenty!
i += 1
end
Ylva
Brighid
Grimm

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Code to Joy Break
def names_with_last
yield ’Ylva’
yield ’Brighid’
# ---- We stopped here... ----
yield ’Shifra’
yield ’Yasmin’
ensure
# ...and jumped to here.
puts "Grimm"
end

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Code to Joy Break
break with a value
What if we want to capture a name?
result = nil
result = names do |name|
if name =~ /^S/
result = name
break
end
end
result # => "Shifra"

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Code to Joy Break
break with a value
result = names do |name|
break name if name =~ /^S/
end
result # => "Shifra"
This effectively overrides the method’s return value.

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Code to Joy Break
Breaking from a #detect
f = open( ’code-to-joy.org’ )
result = f.lines.detect do |line|
break "" if f.lineno >= 100
line =~ /banana/
end
result # => ""

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Code to Joy Subclassing Module
Subclassing Module

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A simple RPG
Race = Struct.new( :name , :strength )
CharacterClass = Struct.new( :name , :charisma )
Character = Struct.new( :name , :race , :char_class )
human = Race.new( "Human" , 9)
wizard = CharacterClass.new( "Tourist" , 3)
player = Character.new( "Rhincewind" , human, wizard)

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What we’d like
Ideally, attributes would be delegated to either race or char_class.
player.name # => "Rhincewind"
player.strength # => 9
player.charisma # => 3

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Using Forwardable
require ’forwardable’
Character = Struct.new( :name , :race , :char_class ) do
extend Forwardable
def_delegators :race , :strength
def_delegators :char_class , :charisma
end

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Evolving with Forwardable
Race = Struct.new( :name , :strength , :constitution )
human = Race.new( "Human" , 9, 5)
# ...
extend Forwardable
def_delegators :race , :strength , :constitution
# ...
end
Every change has to be made twice.

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Using SimpleDelegator
require ’delegate’
class Character < SimpleDelegator
def initialize(name, race, char_class)
@name = name
super(race)
end
# ...
end
Only one object supported.

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Subclassing Module
class Delegate < Module
def initialize(attribute)
@attribute = attribute
super() do
# see next slide...
end
end
end

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Subclassing Module
# ...
define_method( :method_missing ) do
|message, *args, &block|
target = send(attribute)
if target.respond_to?(message)
target.public_send(message, *args, &block)
else
super(message, *args, &block)
end
end
# ...

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Subclassing Module
# ...
define_method(:method_missing) do
|message, *args, &block|
target = send(attribute)
if target.respond_to?(message)
target.public_send(message, *args, &block)
else
super(message, *args, &block)
end
end
# ...

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Subclassing Module
class Delegate < Module
# ...
def to_s
"Delegate( #{ @attribute.inspect } )"
end
end

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Subclassing Module
include Delegate.new( :race )
include Delegate.new( :char_class )
end

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Subclassing Module
player.class.ancestors # =>
[Character,
Delegate( :char_class ),
Delegate( :race ),
Struct, ...]

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Subclassing Module
Race = Struct.new( :name , :strength )
CharacterClass = Struct.new( :name , :charisma )
# ...
player = Character.new( "Rhincewind" , human, wizard)
player.name # => "Rhincewind"
player.strength # => 9
player.charisma # => 3
A chain of responsibility:
1 self
2 self.char_class
3 self.race
4 Other ancestors. . .

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Subclassing Module
• Creates a new “kind” of module
• Enables us to add state to the modules a class includes
• Enabled us to implement a new type of message delegation in
Ruby

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Code to Joy MINASWAN
My Favorite Thing of All
MINASWAN

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Code to Joy Conclusion
Sometimes we get discouraged
• Technical debt got you down?

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• Community drama bumming you out?

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• If you’re blue, don’t know where to go to. . .

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• . . . practice joyful coding

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• . . . practice joyful coding
• How?

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Defend your joy
• There’s no metric for joyful code

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Defend your joy
• Shared code is joyful code

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Defend your joy
• If you want to feel good about your craft. . .

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Defend your joy
• . . . give someone a “wow” moment.

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Defend your joy
• Show one person something awesome.

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Defend your joy
• Show one person something awesome.
• I promise you’ll feel better!

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Thank You
• Rate! http://spkr8.com/t/16041
• Contact! [email protected]
• Tweet! @avdi
• Read! http://conﬁdentruby.com
• 20% off: GOGARUCO2012
• . . . or send me a postcard!

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Code to Joy

Code to Joy

avdi

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