ROR Lab. (DD1-1)

Active Support Core Extensions (1), RailsGuides

Transcript

1. Active Support Core Extensions ROR lab. DD-1 - The 1st round - March 16, 2013 Hyoseong Choi
2. • Ruby on Rails components • actionmailer • actionpack • activerecord • activesupport ... Active Support
3. • Ruby on Rails components • actionmailer • actionpack • activerecord • activesupport ... Active Support
4. Active Support • Ruby language extensions • Utility classes • Other transversal stuff
5. Core Extensions Stand-Alone Active Support require 'active_support' “blank?” method Grouped Core Extensions require 'active_support/core_ext/object' All Core Extensions require 'active_support/core_ext' All Active Support require 'active_support/all' require 'active_support/core_ext/object/blank' Cherry-picking
6. Core Extensions Active Support within ROR Application require 'active_support/all' Default config.active_support.bare = true Barebone setting with Cherry-pickings
7. Ext. to All Objects • blank? ‣ nil and false ‣ whitespaces : spaces, tabs, newlines ‣ empty arrays and hashes ‣ empty? true • present? ‣ !blank? 0 and 0.0 ! blank active_support/core_ext/object/ blank.rb
8. Ext. to All Objects • presence host = config[:host].presence || 'localhost' active_support/core_ext/object/ blank.rb
9. Ext. to All Objects active_support/core_ext/object/ duplicable.rb • duplicable? "".duplicable? # => true false.duplicable? # => false Singletons : nil, false, true, symobls, numbers, and class and module objects
10. Ext. to All Objects active_support/core_ext/object/try.rb • try def log_info(sql, name, ms) if @logger.try(:debug?) name = '%s (%.1fms)' % [name || 'SQL', ms] @logger.debug(format_log_entry(name, sql.squeeze(' '))) end end @person.try { |p| "#{p.first_name} #{p.last_name}" } • try!
11. Ext. to All Objects active_support/core_ext/kernel/ singleton_class.rb • singleton_class nil => NilClass true => TrueClass false => FalseClass
12. Singleton Class? • When you add a method to a specific object, Ruby inserts a new anonymous class into the inheritance hierarchy as a container to hold these types of methods. http://www.devalot.com/articles/2008/09/ruby-singleton anonymous class foobar = [ ] def foobar.say “Hello” end
13. Singleton Class? http://www.devalot.com/articles/2008/09/ruby-singleton anonymous class module Foo def foo "Hello World!" end end foobar = [] foobar.extend(Foo) foobar.singleton_methods # => ["foo"] foobar = [] class << foobar def foo "Hello World!" end end foobar.singleton_methods # => ["foo"] foobar = [] foobar.instance_eval <<EOT def foo "Hello World!" end EOT foobar.singleton_methods # => ["foo"] foobar = Array.new def foobar.size "Hello World!" end foobar.size # => "Hello World!" foobar.class # => Array bizbat = Array.new bizbat.size # => 0
14. Singleton Class? http://www.devalot.com/articles/2008/09/ruby-singleton class Foo def self.one () 1 end class << self def two () 2 end end def three () 3 end self.singleton_methods # => ["two", "one"] self.class # => Class self # => Foo end • Practical Uses of Singleton Classes class method class method anonymous class
15. Ext. to All Objects active_support/core_ext/kernel/ singleton_class.rb • class_eval(*args, &block) class Proc def bind(object) block, time = self, Time.now object.class_eval do method_name = "__bind_#{time.to_i}_#{time.usec}" define_method(method_name, &block) method = instance_method(method_name) remove_method(method_name) method end.bind(object) end end
16. Ext. to All Objects active_support/core_ext/object/ acts_likes.rb • acts_like?(duck) some_klass.acts_like?(:string) same interface? def acts_like_string? end acts_like_date? (Date class) acts_like_time? (Time class) for example
17. Ext. to All Objects active_support/core_ext/object/ to_param.rb • to_param(=> to_s) a value for :id placeholder class User def to_param "#{id}-#{name.parameterize}" end end user_path(@user) # => "/users/357-john-smith" ➧ => The return value should not be escaped! overwriting
18. Ext. to All Objects active_support/core_ext/object/ to_query.rb • to_query a value for :id placeholder class User def to_param "#{id}-#{name.parameterize}" end end current_user.to_query('user') # => user=357-john-smith ➧ => escaped!
19. Ext. to All Objects active_support/core_ext/object/ to_query.rb • to_query escaped account.to_query('company[name]') # => "company%5Bname%5D=Johnson+%26+Johnson" {:c => 3, :b => 2, :a => 1}.to_query # => "a=1&b=2&c=3" [3.4, -45.6].to_query('sample') # => "sample%5B%5D=3.4&sample%5B%5D=-45.6" {:id => 89, :name => "John Smith"}.to_query('user') # => "user%5Bid%5D=89&user%5Bname%5D=John+Smith"
20. Ext. to All Objects active_support/core_ext/object/ with_options.rb • with_options class Account < ActiveRecord::Base has_many :customers, :dependent => :destroy has_many :products, :dependent => :destroy has_many :invoices, :dependent => :destroy has_many :expenses, :dependent => :destroy end class Account < ActiveRecord::Base with_options :dependent => :destroy do |assoc| assoc.has_many :customers assoc.has_many :products assoc.has_many :invoices assoc.has_many :expenses end end
21. Ext. to All Objects active_support/core_ext/object/ with_options.rb • with_options I18n.with_options locale: user.locale, scope: "newsletter" do |i18n| subject i18n.t(:subject) body i18n.t(:body, user_name: user.name) end # app/views/home/index.html.erb <%=t 'greet_username', :user => "Bill", :message => "Goodbye" %> # config/locales/en.yml en: greet_username: "%{message}, %{user}!" http://guides.rubyonrails.org/i18n.html interpolation key
22. Ext. to All Objects active_support/core_ext/object/ with_options.rb • with_options en: activerecord: models: user: Dude attributes: user: login: "Handle" # will translate User attribute "login" as "Handle" http://guides.rubyonrails.org/i18n.html scope of i18n config/locales/en.yml
23. Ext. to All Objects active_support/core_ext/object/ instance_variable.rb • Instance Variables class C def initialize(x, y) @x, @y = x, y end end C.new(0, 1).instance_values # => {"x" => 0, "y" => 1}
24. Ext. to All Objects active_support/core_ext/kernel/ reporting.rb • Silencing Warnings, Streams, and Exceptions silence_warnings { Object.const_set "RAILS_DEFAULT_LOGGER", logger } silence_stream(STDOUT) do # STDOUT is silent here end quietly { system 'bundle install' } # If the user is locked the increment is lost, no big deal. suppress(ActiveRecord::StaleObjectError) do current_user.increment! :visits end $VERBOSE even in subprocesses silencing exceptions silencing streams
25. Ext. to All Objects active_support/core_ext/object/ inclusion.rb • in? 1.in?(1,2) # => true 1.in?([1,2]) # => true "lo".in?("hello") # => true 25.in?(30..50) # => false 1.in?(1) # => ArgumentError [1,2].include? 1 # => true "hello".include? "lo" # => true (30..50).include? 25 # => false • include? (array method)
26. ROR Lab.