**Draft
Varying the Algorithm with the Template Method Варирование алгоритма с помощью Шаблонного Метода
class Users::Physic < Users::Base
def initialize name, website
@name = name
@website = website
end
def description
puts("#{@name} [#{@website}] (#{class.to_s})")
end
end
class Users::Juristic < Users::Base
def initialize name, company
@name = name
@company = company
end
def description
puts("#{@name} [#{@company}] (#{class.to_s})")
end
end
class Users::Base
def description
puts("#{printable_name} (#{class.to_s})")
end
def printable_name
'abstract name'
end
end
class Users::Physic < Users::Base
def initialize name, website
@name = name
@website = website
end
def printable_name
"#{@name} [#{@website}]"
end
end
class Users::Juristic < Users::Base
def initialize name, company
@name = name
@company = company
end
def printable_name
"#{@name} [#{@company}]"
end
end
> physic = Users::Physic.new('Google', 'http://google.com')
> physic.description
> 'Google [http://google.com] (Users::Physic)'
=> juristic = Users::Juristic.new('Yandex', 'Yandex Inc')
=> juristic.description
> 'Yandex [Yandex Inc] (Users::Juristic)'
=> abstract_user = Users::Base.new
=> abstract_user.description
> 'abstract name (Users::Base)'
Replacing the Algorithm with the Strategy Замена Алгоритма с помощью Стратегии
class Users::Base
def description
'It's a description of Users::Base'
end
end
class PlainTextFormatter
def report text
puts '<plain text>'
puts text
puts '<plain text>'
end
end
class HTMLFormatter
def report text
puts '<html>'
puts '<head>'
puts '</head>'
puts '<body>'
puts text
puts '</body>'
puts '</html>'
end
end
class Users::Base def initialize name, formatter @name = name @formatter = formatter end def report fomatter.report(self) end end class PlainTextFormatter def report context puts '<plain text>' puts context.name puts '<plain text>' end end class HTMLFormatter def report context puts '<html>' puts '<head>' puts '</head>' puts '<body>' puts context.name puts '</body>' puts '</html>' end end
> user = Users::Base.new('username', HTMLFormatter.new)
> user.report
> user = Users::Base.new('username', PlainTextFormatter.new)
> user.report
class Users::Base def initialize name, &formatter @name = name @formatter = formatter end def report formatter.call self end end
> PLAIN_TEXT_FORMATTER = lambda do |context|
> puts '<plain text>'
> puts context.name
> puts '<plain text>'
> end
> HTML_FORMATTER = lambda do |context|
> puts '<html>'
> puts '<head>'
> puts '</head>'
> puts '<body>'
> puts context.name
> puts '</body>'
> puts '</html>'
> end
> user = Users::Base.new('username', PLAIN_TEXT_FORMATTER)
> user.report
> user = Users::Base.new('username', HTML_FORMATTER)
> user.report
Keeping Up with the Times with the Observer
class Users::Base attr_reader :payment def initialize name, payment, payment_notification @name = name @payment = payment @payment_notification = payment_notification end def payment= new_payment @payment = new_payment payment_notification.update(self) end end class PaymentNotification def update puts "#{self.name} payment updated to #{self.payment}" end end
module Observers def initialize @observers=[] end def add_observer &observer @observers << observer end def delete_observer observer @observers.delete(observer) end def notify_observers @observers.each do |observer| observer.call(self) end end end class Users::Base include Observers attr_reader :payment def initialize name, payment super() @name = name @payment = payment end def payment= new_payment @payment = new_payment notify_observers end end
> user = Users::Base.new('username', 35000)
> user.add_observer do |changed_user|
> puts "#{changed_user.name} payment updated to #{changed_user.payment}"
> end
> user.payment = 40000
=> 'username payment updated to 40000'
class Users::Base < ActiveRecord attr_accessor :payment def initialize name, payment super() @name = name @payment = payment end def payment= new_payment @payment = new_payment notify_observers end end class NotificationObserver < ActiveRecord::Observer observe Users::Base def after_update(user) puts "#{user.name} updated" end end
> user = Users::Base.new('username', 30000)
> user.payment = 45000
=> 'username updated'
Assembling the Whole from the Parts with the Composite
class Users::Base < ActiveRecord
attr_reader :payment
def initialize name, payment
super()
@name = name
@payment = payment
@children = []
end
def add child
@children << child
end
def children
@children
end
end
> user_one = Users::Base.new('username', 30000)
> user_one.add Users::Base.new('username', 40000)
> user_one.add Users::Base.new('username',50000)
> user_one.children[0].add Users::Base.new('username', 60000)
>
> payment_sum = user_one.payment + user_one.children[0].payment
> + user_one.children[1].payment + user_one.children[0].children[0].payment
class UsersComposite < User
def payment_sum
payment_sum = 0.0
@children.each{|child| time += child.payment}
payment_sum
end
def << child
add child
end
def [] index
@children[index]
end
def []= index, new_child
@children[index] = new_child
end
> composite = UsersComposite.new
> composite << user_one
> payment_sum = composite.payment_sum
Reaching into a Collection with the Iterator
class ExternalArrayIterator
def initialize(array)
@array = array
@index = 0
end
def has_next?
@index < @array.length
end
def next_item
value = @array[@index]
@index += 1
value
end
end
>> array = [1,'aaa', Users::Base.new]
>> iterator = ExtrenalArrayIterator.new(array)
>> while iterator.has_next?
>> iterator.next_item.to_s
>> end
class ArrayIterator < Enumerable
end
class InternalArrayIterator
def self.for_each_element(array)
i = 0
while i < array.length
yield(array[i])
i += 1
end
end
end
>> array = [1, 'aaa', Users::Base.new]
>> InternalArrayIterator.for_each_element(array){|element| element.to_s}
Getting Things Done with Commands
class Users::Administrator < Users::Base
def on_action
#Maybe get list of all users
end
end
class Users::Support < Users::Base
def on_action
#Maybe get list of all users except administrators
end
end
class Users::Base
attr_accessor :command
def initialize command
@command = command
end
def on_action
@command.execute if @command
end
end
class UsersListCommand
def execute
end
end
class UserListExceptAdminsCommand
def execute
end
end
> Users::Administrator.new(UsersListCommand.new)
> Users::Support.new(UserListExceptAdminsCommand.new)
class Users::Base
attr_accessor :command
def initialize &block
@command = block
end
def on_action
@command.call if @command
end
end
> Users::Base.new do
>
> end