Ruby Bits Slides

8/14/2019 Ruby Bits Slides

1/109

E X P R E S S I O N S


2/109

Bad Code

I C O N S

Worse Code

Good Code

Awesome Code


3/109

Unless is more intuitive

U N L E S S

if ! tweets.empty? puts "Timeline:" puts tweetsend

unless tweets.empty? puts "Timeline:" puts tweetsend


4/109

Unless with else is confusing

U N L E S S W I T H E L S E

unless tweets.empty? puts "Timeline:"

puts tweets

end

else puts "No tweets found - better follow some people!"

if tweets.empty? puts "No tweets found - better follow some people!"else puts "Timeline:" puts tweetsend


5/109

nil treated as false

N I L I S FA L S E ! Y

if attachment.file_path != nil attachment.postend

if attachment.file_path attachment.postend


6/109

treated as true!

O N LY N I L I S FA L S E ! Y

""

treated as true!0

treated as true![]

unless name.length warn "User name required"end

wil l ne ve r be f al s e !


7/109

try inline if/unless

I N L I N E C O N D I T I O N A L S

if password.length < 8 fail "Password too short"

end

fail "Password too short" if password.length < 8

unless username fail "No user name set"end

fail "No user name set" unless username


8/109

use && instead

S H O RT ! C I R C U I T ! A N D

if user

if user i f us e r is n i l

s e c o nd ha l f ne v

if user.signed_in? #... end

&& user.signed_in?

end

#...end


9/109

1

S H O RT ! C I R C U I T A S S I G N M E N T

result = nil || 1

result = 1 || nil

result = 1 || 2

1

1


10/109

if nil, default to empty array

D E FA U LT VA L U E S ! O R

tweets = timeline.tweets || []

tweets = timeline.tweetstweets = [] unless tweets


11/109

not evaluated unless

current session is nil

S H O RT ! C I R C U I T E VA L U AT I O N

def sign_in current_session || sign_user_inend

bu t co nsi d er w h et h er i f / t h en w o u l d be mo r e l e g i bl e!


12/109

i_was_set = 1

C O N D I T I O N A L A S S I G N M E N T

ass i g ns I F t he re s

n o e x is t i n g va l ue

i_was_not_set ||= 2

i_was_set ||= 2

puts i_was_set

puts i_was_not_set

1

2


13/109

use conditional assignment

C O N D I T I O N A L A S S I G N M E N T

options[ :country ] ||= 'us'options[ :privacy ] ||= trueoptions[ :geotag ] ||= true

options[ :country ] = 'us' if options[ :country ].nil?options[ :privacy ] = true if options[ :privacy ].nil?options[ :geotag ] = true if options[ :geotag ].nil?


14/109

if list_name "/#{user_name}/#{list_name}"else "/#{u ser_name}"end

assign the value of the if statement

C O N D I T I O N A L R E T U R N VA L U E S

options[ :path ] =

if list_name options[ :path ] = "/#{user_name}/#{list_name}"else options[ :path ] = "/#{user_name}"end
http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/


15/109

def list_url ( user_name, list_name )


"https://twitter.com/#{user_name}"

"https://twitter.com/#{user_name}/#{list_name}"if list_name

url =else

url =endurl

end
http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/


16/109


def list_url ( user_name, list_name )if list_name

"https://twitter.com/#{user_name}/#{list_name}"else

"https://twitter.com/#{user_name}"end

end
http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/http://livepage.apple.com/


17/109

C A S E S TAT E M E N T VA L U E

client_url = case client_namewhen "web"

"http://twitter.com"when "Facebook"

"http://www.facebook.com/twitter"else

nilend
http://www.facebook.com/twitterhttp://www.facebook.com/twitterhttp://twitter.com/http://twitter.com/


18/109

when

when

else

nil

end

popularity = case tweet.retweet_count0.. 9

10 .. 99"trending"

"hot"

C A S E ! R A N G E S


19/109

C A S E ! R E G E X P S

:mention

:direct_message

:publicelse

end

tweet_type = case tweet.statuswhen / \A @\w +/

when / \A d\s +\w +/


20/109

C A S E ! W H E N / T H E N

:mention:direct_message:public

end

tweet_type = case tweet.statusthenthen

when / \A @\w +/when / \A d\s +\w +/else


21/109

E X P R E S S I O N S


22/109

M E T H O D S A N D C L A S S E S


23/109

location isnt always used

O P T I O N A L A R G U M E N T S

def tweet ( message, lat, long ) #...

endtweet( "Practicing Ruby-Fu!" , nil , nil )

tweet( "Practicing Ruby-Fu!" )

location is now optiona

= nil = nil

, so lets add defdef tweet ( message, lat , long ) #...end


24/109

long parameter list

N A M E D A R G U M E N T S ! H A S H

tweet( "Practicing Ruby-Fu!" , 28.55 , - 81.33 , 227946 )

tweet( "Practicing Ruby-Fu!" , nil , nil , 227946 )

calls to it are hard

have to keep placeholders for

arguments youre not using

= nil = nildef tweet ( message, lat , long )reply_id = nil, #...

end


25/109

H A S H A R G U M E N T S

status = Status . new

status.lat = options[ :lat ] status.long = options[ :long ] status.body = message status.reply_id = options[ :reply_id ] status.postend

hash

reference keysfrom hash

def tweet ( message, options = {} )


26/109

H A S H A R G U M E N T S

tweet( "Practicing Ruby-Fu!" , :lat => 28.55 , :long => - 81.33 , :reply_id => 227946) keys show meaning

all combined intooptions argument

def tweet ( message, options = {} )


27/109


C O M B O X 3 !

Repositioning the keys

Using Ruby 1.9 hash syntax

C O M B O X 2 !

tweet( "Practicing Ruby-Fu!" ,

lat: 28.55 ,long: - 81.33 ,reply_id: 227946

)

tweet( "Practicing Ruby-Fu!" ,

lat: 28.55,

long: - 81.33,

reply_id: 227946

)

N A M E D A R G U M E N T S H A S H


28/109


C O M B O X 4 !

tweet( "Practicing Ruby-Fu!" )C O M B O X 5 !

Keys are optional

Complete hash is optional

tweet( "Practicing Ruby-Fu!" ,reply_id: 227946

)

E X C E P T I O N S


29/109

E X C E P T I O N S

if tweets.empty?

magic return value

cant be sure its an error

endend

[]else

list.tweetsif list.authorized?( @user )

def get_tweets ( list )

end

alert "No tweets were found!" + "Are you authorized to access this list?"

tweets = get_tweets(my_list)

E X C E P T I O N S


30/109

E X C E P T I O N S

raise an Exception instead

caller KNOWS theres a problem

def get_tweets ( list )unless list.authorized?( @user )

raise AuthorizationException . newendlist.tweets

end

begintweets = get_tweets(my_list)

rescue AuthorizationExceptionwarn "You are not authorized to access this list."

end

S P L AT A R G U M E N T S


31/109

def mention ( status, *names ) tweet( "#{names.join(' ')} #{status}" )end

S P L AT A R G U M E N T S

mention( 'Your courses rocked!' , 'eallam' , 'greggpollack' , 'jasonvanlu

status names[0] names[1] names[2]

eallam greggpollack jasonvanlue Your courses rocked!

Y O U N E E D A C L A S S W H E N


32/109

Y O U N E E D A C L A S S W H E N . . .

Kutcher, AshtonWheaton, Wil, Madonna

your users shouldnthave to deal withedge cases

O U T P U T:

user_names = [ [ "Ashton" , "Kutcher" ], [ "Wil" , "Wheaton" ], [ "Madonna" ]]user_names.each { | n| puts "#{n[ 1]}, #{n[ 0]}" }



33/109


class Name def initialize ( first, last = nil )

@first = first @last = last end def format [ @last , @first ].compact.join( ', ' ) endend

behavior!

state!



34/109


user_names = []user_names


35/109

O V E R S H A R I N G ?

shouldnt be able to do this!

def baz= ( valu @baz = valueenddef baz @bazend

attr_accessorclass Tweet attr_accessor :status , :created_at def initialize ( status ) @status = status @created_at = Time . new endend

tweet = Tweet . new( "Eating breakfast." )tweet.created_at = Time . new( 2084 , 1, 1, 0, 0, 0, "-07:00" )



36/109


doesnt define asetter!

undefined method 'created_at='

class Tweet attr_accessor :status

:created_at def initialize ( status ) @status = status @created_at = Time . new endend

attr_reader

tweet = Tweet . new( "Eating breakfast." )tweet.created_at =

Time . new( 2084 , 1, 1, 0, 0, 0, "-07:00" )

R E ! O P E N I N G C L A S S E S


37/109

R E O P E N I N G C L A S S E S

not so r eada

tweet = Tweet . new( "Eating lunch." )puts tweet.to_s

#

class Tweet def to_s "#{ @status }\n #{ @created_at }" endendtweet = Tweet . new( "Eating lunch." )puts tweet.to_s

so just r e

class and

Eating lunch.

2012-08-02 12:20:02 -0700

R E ! O P E N I N G C L A S S E S


38/109

R E O P E N I N G C L A S S E S

You can re-open and change any class.

Beware! You don't know who relies on the old functionality

You should only re-open classes that you yourself own.

S E L F


39/109

S E L F

class UserList attr_accessor :name def initialize ( name ) name = name endend

class UserList

attr_accessor :name def initialize ( name ) self .name = name endend

list = UserList . new ( 'celebrities'list.name

nil th is j us t re -se ts the

na me loca l va r iab le!

b u t th is ca l ls na me=

o n the c u r re n t ob jec t

list = UserList . new ( 'celebrities'

list.name

"celebrities"


40/109

M E T H O D S A N D C L A S S E S


41/109

C L A S S E S

E N C A P S U L AT I O N


42/109

def send_tweet ( status, owner_id ) retrieve_user(owner_id) ...end

send_tweet( "Practicing Ruby-Fu!" , 14 )

should not be responsible for retrieving a user



43/109

Passing around data as strings and numbers breaks encapsula

Places using that data need to know how to handle it.

Individual changes require updates at various places.



44/109

one parameter!

class Tweet attr_accessor ...

def owner retrieve_user(owner_ endend

tweet = Tweet . newtweet.status = "Practicing Ruby-Fu!"tweet.owner_id = current_user.id

send_tweet(tweet)

def send_tweet ( message ) message.owner ...end



45/109

May not be worth the overhead of a class if all you have is d

An option hash might su! ce.

When you have behavior to go with the data, it's time to intro

V I S I B I L I T Y


46/109

joe = User . new 'joleo = User . new 'le

joe.up_vote(leo)

class User

def up_vote ( friend )

bump_karma friend.bump_karma end

def bump_karma puts "karma up for #{name} "end

should not be partof the public API

karma up fkarma up f

end

V I S I B I L I T Y


47/109


joe.up_vote(leo)


privateprivate method 'bumfor #


48/109


joe.up_vote(leo)


protected

karma up fkarma up f

hidden from outsfrom other instan

class User

def up_vote ( friend )

bump_karma friend.bump_karma end

end

I N H E R I TA N C E


49/109

d u p l ica ted f u nc t io

attr_accessor :title , :size , :url


def to_s "#{ @title }, {@size}" end

class Image

end

class Video

end

def to_s"#{ @title }, {@size}"

end

I N H E R I TA N C E


50/109

m uch D R Ye r!


class Image < Attachmentend

class Video < Attachmentend

class Video < Atta attr_accessor

end

if a me thod o n l yse nse fo r o ne

p u t i t the re.

class Attachment

def to_s"#{ @title }, #{ @size }"

endend

S U P E R


51/109

class User def initialize ( name ) @name = name endend

follower = Follower . new( "Oprah" , "aplusk" )follower.relationship

" follows aplusk" n o @ na me!

d oes n t ca l l

Use r # i n i t ia l ize

class Follower < User def initialize ( name, following ) @following = following end def relationship "#{ @name} follows #{ @following } endend

S U P E R


52/109

class User def initialize ( name ) @name = name endend Ca l ls

Us e r # i n i t ia l iz e

class Follower < User def initialize ( name, following ) @following = following

end def relationship "#{ @name} follows #{ @following } endend

super (name)

follower = Follower . new( "Oprah" , "aplusk" )follower.relationship

"Oprah follows aplusk"

S U P E R


53/109

class Parent < Grandparentend

child = Child . newputs child.my_method

not he r e Grandparent: my_methodChild: my_method called

class Grandparentdef my_method

"Grandparent: my_method called"end

end

class Child < Parentdef my_method

string = super"#{string} \n Child: my_method called"

endend

S U P E R


54/109

Grandparent: 'w00t!Child: 'w00t!'

sa me as s u pe r (a r g u me n t )

class Grandparentdef my_method ( argument )

"Grandparent: '#{argument}'"

endend

class Child < Parentdef my_method ( argument )

string = super

"#{string} \n Child: '#{argument}'"end

end

child = Child . newputs child.my_method(

O V E R R I D I N G M E T H O D S


55/109

t y p ica l case

the oddba l lthumbnail

player

class Attachment def preview

endend

Th is is s lo w

case @typewhen :jpg , :png , :gif

when :mp3

end

O V E R R I D I N G M E T H O D S


56/109

thumbnail player

class Attachment def preview

endend the defa u l t s pec ia l h

a nd l i

class Audio < Attachment def preview

endend

H I D E I N S TA N C E VA R I A B L E S


57/109

a l ot of r epetition when wor kin g with these...

class Userdef tweet_header

[ @first_name , @last_name ].join( ' ' )

def profile[ @first_name , @last_name ].join( ' ' ) + @description

endend

end



58/109

you can use an accessor met hod , even wit hin t he same cl ass

class User

def tweet_header

[ @first_name , @last_name ].join( ' ' )

enddef profile

+ @description endend

display_name

display_name

def display_name

end



59/109

class User def display_name title = case @gender when :female married? ? "Mrs." : "Miss" when :male "Mr." end [title, @first_name , @last_name ].join( ' ' ) endend

if you need to chan ge the lo gic

lou can do it in just one place!

C O M B O X


60/109


61/109

A C T I V E S U P P O R T

A C T I V E S U P P O RT


62/109

Install It

$ gem install activesupport$ gem install i18n

Load It

require 'active_support/all'

not a depebut it is h

C O R E E X T E N S I O N S : A R R AY


63/109

p ad s r emoves t he el ement i t spl i t s on

array = [ 0, 1, 2, 3, 4, 5, 6]

array.from( 4)array.to( 2)array.in_groups_of( 3)array.split( 2)

[4, 5, 6][0, 1, 2][[0, 1, 2], [3, 4, 5], [6, nil, nil]][[0, 1], [3, 4, 5, 6]]

C O R E E X T E N S I O N S : D AT E


64/109

Fri, 21 Dec 2012 14:27:45 +0000

apocalypse = DateTime . new( 2012 , 12 , 21 , 14 , 27 , 45 )

Fri, 21 Dec 2012 00:00:00 +0000

apocalypse.at_beginning_of_day

Mon, 31 Dec 2012 23:59:59 +0000

apocalypse.at_end_of_month

Sun, 01 Jan 2012 00:00:00 +0000

apocalypse.at_beginning_of_year

C O R E E X T E N S I O N S : D AT E


65/109

Fri, 21 Dec 2012 14:27:45 +0000

apocalypse = DateTime . new( 2012 , 12 , 21 , 14 , 27 , 45 )

Wed, 05 Apr 2017 14:27:45 +0000

apocalypse.advance( years: 4, months: 3, weeks: 2, days: 1)

Sat, 22 Dec 2012 14:27:45 +0000

apocalypse.tomorrow

Thu, 20 Dec 2012 14:27:45 +0000

apocalypse.yesterday

C O R E E X T E N S I O N S : H A S H


66/109

difference betwtwo hashes

turn keys into st

options = {user: 'codeschool' , lang: 'fr' }new_options = {user: 'codeschool' , lang: 'fr' , password: 'dunno

{:password=>"dunno"}

options.diff(new_options)

{"user"=>"codeschool", "lang"=>"fr"}

options.stringify_keys



67/109

options = { lang: 'fr' , user: 'codeschool'

}

value s f r omt his has h win

options.reverse_merge(defaults)

defaults = { lang: 'en' , country: 'us'

}

lang: 'fr' , user: 'codeschool' ,

country: 'us'

{

}



68/109

Unknown key(s): password (ArgumentError)

new_options = {user: 'codeschool' , lang: 'fr' , password: 'dunno

{:user=>"codeschool", :lang=>"fr"}

new_options.except( :password )

new_options.assert_valid_keys( :user , :lang )

remove

throws an exception if the hash contaiany keys besides those listed here

C O R E E X T E N S I O N S : I N T E G E R


69/109

d e t e r mine od d a nde ve n numbe r s

tweets.each_with_index do | tweet , index | puts "#{tweet}" end

def background_class ( index ) return 'white' if index.odd? return 'grey' if index.even? end

I had eggs for breakfast.

@codeschool pwns.Shopping!Bedtime.

I N F L E C T O R


70/109

"1st place!"

"#{ 1.ordinalize} place!"

"2nd place."

"#{ 2.ordinalize} place."

"23rd place."

"#{ 23 .ordinalize} place."

or d inal ize number sto st r in gs

I N F L E C T O R

pl li


71/109

"users"

"user" .pluralize

"woman"

"women" .singularize

"octopi"

"octopus" .pluralize

pl ur al ize and sin gul ar ize str in gs

it knows common speand e ve n s ome uncom

I N F L E C T O R


72/109

"Ruby Bits"

"ruby bits" .titleize

"Account options"

"account_options" .humanize

capitalize ever y w

ad d spaces and capf ir st wor d


73/109


74/109

M O D U L E S

N A M E S PA C EIMAGE UTILS RB


75/109

IMAGE_UTILS .RB

RUN.RB

pollutes glob

potential conmethods wit

def preview

end

transferdefend

( image )

image,( )destination

preview(image)image = user.image

require 'image_utils'

N A M E S PA C EIMAGE UTILS RB


76/109

IMAGE_UTILS .RB

RUN.RB

def preview

end

transferdefend

self.module ImageUtils

end

( image )

image,( )destination

preview(image)


image = user.image

self.

ImageUtils .

M I X I NIMAGE UTILS RB


77/109

IMAGE_UTILS .RB

AVATAR.RB Included as insta

def preview

end

transferdefend

module ImageUtils

end

can accesson objects( )destination

class Image include ImageUtilsend


image = user.imageimage.preview

RUN.RB

A N C E S T O R S


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class Image include ImageUtilsend

Adding modul

ancestors chai

Image .ancestors

Image .included_modules

modules only

[Image, ImageUtils, Object, Kernel, BasicObject]

[ImageUtils, Kernel]

M I X I N S V S C L A S S I N H E R I TA N C E

class Shareableclass Post


79/109

class Shareabledef share_on_facebookend

def share_on_facebookend


end

end

end

end

class Post

class Image

class Tweet


< Shareableclass Post class Shareable


80/109

end


< Shareable

< Shareable

< Shareable

end

end

end

A class can only have o

Some behaviors are notInheritance suggests sp

class Post

class Image

class Tweet

class Shareable


module Shareableclass Post


81/109

module Shareable

end

def share_on_facebookendend

end

end

include Shareable

include Shareable

include Shareable

class Post

class Image

class Tweet


class Post

module Shareable


82/109

include Shareable

include Shareable

include Shareable

include Favoritable

include Favoritable

include Favoritable

module Favoritable

end

def add_to_deliciousend

class Post

class Image

class Tweet

module Shareable

end


end

end

end

M I X I N


83/109

extend Searchable

Included as class methods

module Searchable def find_all_from ( user endend

class Tweet

end

Tweet .find_all_from( '@GreggPollack' )

M I X I N


84/109

image.previewimage = user.image

use include tomethods as instance

use extend to exposemethods as class methods

extend Searchableclass Tweet

end

Tweet .find_all_from( '@GreggPollack' )

class Imageinclude ImageUt

end

M I X I N


85/109

image. extend ( ImageUtils )

image = Image . newimage.previewthe module will not be available in o

an object is extending the mo

image = Image . new

image.preview

NoMethodError: undefined method preview' for #

module ImageUtilsdef preview

endend

class Imageend

H O O K S ! S E L F. I N C L U D E D


86/109

extend ImageUtils :: Cinclude ImageUtils

def fetch_from_twitter ( user )

end

endend

module ClassMethods

module ImageUtils

def preview

end

def transfer ( destination )end

class Image

end


Image .fetch_from_twitter(

H O O K S ! S E L F. I N C L U D E D


87/109

def fetch_from_twitter ( user )end

module ClassMethods

sellf.included is calledwhen a module is incl

in this case, the modulename can be anythingend

end


Image .fetch_from_twitter(

extend ImageUtils :: Cinclude ImageUtils

class Image

end

module ImageUtils

def previewend

def transfer ( destination )end

def self.included ( base )

base. extend ( ClassMethods )end

A C T I V E S U P P O RT: : C O N C E R N


88/109

def self.included ( base )

base. extend ( ClassMethods )base.clean_up

end

module ImageUtils

module ClassMethodsdef fetch_from_twitter ( user )end

def clean_upend

endend

class Imageinclude ImageUtils

end


i ' i / 'gem install activesu


89/109

require 'active_support/concern'

includedclean_up

do

extend ActiveSupport :: Concern

} included block is executhe context of the Imagend

ActiveSupport::Concern for a module named Clas

module ImageUtils

module ClassMethodsdef fetch_from_twitter ( user )end

def clean_upend

endend

class Imageinclude ImageUtils

end


i l d d ( b )d f lfmodule ImageUtils class Image


90/109

base is Image class

ImageProceson

include ImageProcessinincluded ( base ) def self.

base. extend ( ClassMethods )

calls method onImage class

end

module ImageProcessing

end

def self.included ( base )base.clean_up

end

module ClassMethodsdef clean_up ; end

endend

include ImageUtils

end


i l d d ( b )d f lfmodule ImageUtils class Image


91/109

include ImageProcessinincluded ( base ) def self.base. extend ( ClassMethods )

end


end


end

end

end

undefined method er

base is ImageProcessi


end

include ImageUtils


incl ded ( base )def selfmodule ImageUtils class Image


92/109

include ImageProcessinincluded ( base ) def self.base. extend ( ClassMethods )

end


end


end

end

end


base is Image class

Dependeproperly


end

include ImageUtils

A C T I V E S U P P O RT: : C O N C E R Nmodule ImageUtils


class Image


93/109


included doclean_up

Dependeproperly

include ImageProcessinend


include ImageUtilsextend ActiveSupport :: Concern

end

end


end

end


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M O D U L E S


95/109

B L O C K S

U S I N G B L O C K S

words = [ 'Had' 'eggs' 'for' 'breakfast ' ]


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words [ Had , eggs , for , breakfast. ]for index in 0..(words.length - 1) puts words[index]

end

words = [ 'Had' , 'eggs' , 'for' , 'breakfast.' ]words.each { | word | puts word }

D E C L A R I N G B L O C K S

braces if the bloc kwords.each { | word | puts word }


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words.each do | word | backward_word = word.reverse puts backward_wordend

braces i is a s in gle l ine

words.each { | word | puts word }

do /end if i t s m ul t i ple l ines

th is is the F I RS Tof t wo con ven t ions!

D E C L A R I N G B L O C K S

do/end if the bloc khigwords.each do | word |


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backward_words = words.map { | word | word.reverse }

do /e DO ES so me th in g

(has a s ide effec t

| | puts wordend

brac j us t i ts r

th is is the S E CO N D

of t wo con ven t ions!

Y I E L D

def call_this_block_twice


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call_this_block_twice { puts "twitter" }

_ _ _ yield yield

end

twittertwitter

call_this_block_twice { puts "tweet" } tweettweet

Y I E L D!

A R G U M E N T S

def call_this_block


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call_this_block { | myarg | puts myarg }

yield "tweet"end

twe

call_this_block { | myarg | puts myarg.upcase } TW

Y I E L D!

R E T U R N VA L U E

def puts_this_block


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puts_this_block { "tweet" }

puts yieldend

tweet

Y I E L D

def call_this_block


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block_result = yield "foo"

puts block_resultend

call_this_block { | arg | arg.reverse }

"oof"

U S I N G B L O C K S

eclass Timeline


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sa med if f e

def list_tweets@user .friends.each do | friend |

friend.tweets.each { | tweet |

endend puts tweet }

def store_tweets@user .friends.each do | friend |

friend.tweets.each { | tweet |end

tweet.cache

endend

}

Y O U R O W N E A C H

class Timeline


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r e - u

timeline = Timeline . new(user)

timeline.each { | tweet | puts tweet }timeline.each { | tweet | tweet.cache }

var y

def each@user .friends.each do | friend |

friend.tweets.each { | tweet |end yield tweet }

endend

E N U M E R A B L E

yo u i m ple men ted h nowmixin

class Timelinedef each


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timeline.sort_by { | tweet | tweet.created_at }timeline.map { | tweet | tweet.status }timeline.find_all { | tweet | tweet.status =~ / \@codeschool/

each , no w m i x in

En u mer able

you instantl y get all these methods, and mor e!

def each

end

endinclude Enumerable

...

E X E C U T E A R O U N D

update_status ( user , tweet )def def get_list ( user , list_namb i


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endend

post(tweet) retrieve_list(list_name)

e ver y th in g b u t the core

lo g ic is d u pl ica ted!

rescue ConnectionError logger.error(e) ensure sign_out(user) endend

begin sign_in(user)

rescue ConnectionError => elogger.error(e)

ensuresign_out(user)

beginsign_in(user)


while_signed_in_as ( user ) while_signed_in_as(user) defb i


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end

yield

no w yo u can j us t call the

s in gle me thod w i th a bloc k!

tweets = while_signed_in_as(use

post(tweet)end

retrieve_list(list_name)end

rescue ConnectionError => elogger.error(e)

ensuresign_out(user)

end

sign_in(user)begin


def while_signed_in_as ( user )i i ( )


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no need f or be g in /end w i th in a me thod!

C O M B O X 2 !

rescue ConnectionError => elogger.error(e)ensure

sign_out(user)

sign_in(user)

end

yield


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B L O C K S

Date post:	04-Jun-2018
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