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  • How do I include a module in a namespaced class?

    - by snl
    I am having trouble including a module in a namespaced class. The example below throws the error uninitialized constant Bar::Foo::Baz (NameError). What basic piece of Ruby knowledge am I missing here? module Foo module Baz def hello puts 'hello' end end end module Bar class Foo include Foo::Baz end end foo = Bar::Foo.new

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  • How do I use accepts_nested_attributes_for? I cannot use the .build method (!)

    - by Angela
    Editing my question for conciseness and to update what I've done: How do I model having multiple Addresses for a Company and assign a single Address to a Contact, and be able to assign them when creating or editing a Contact? Here is my model for Contacts: class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address_id, :address_attributes belongs_to :company belongs_to :address accepts_nested_attributes_for :address end Here is my model for Address: class Address < ActiveRecord::Base attr_accessible :street1, :street2, :city, :state, :zip has_many :contacts end I would like, when creating an new contact, access all the Addresses that belong to the other Contacts that belong to the Company. So here is how I represent Company: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end Here is how I am trying to create a field in the View for _form for Contact so that, when someone creates a new Contact, they pass the address to the Address model and associate that address to the Contact: <% f.fields_for :address, @contact.address do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> <% end %> When I try to Edit, the field for Street 1 is blank. And I don't know how to display the value from show.html.erb. At the bottom is my error console -- can't seem to create values in the address table: My Contacts controller is as follows: def new @contact = Contact.new @contact.address.build # I GET AN ERROR HERE: says NIL CLASS @contact.date_entered = Date.today @campaigns = Campaign.find(:all, :order => "name") if params[:campaign_id].blank? else @campaign = Campaign.find(params[:campaign_id]) @contact.campaign_id = @campaign.id end if params[:company_id].blank? else @company = Company.find(params[:company_id]) @contact.company_name = @company.name end end def create @contact = Contact.new(params[:contact]) if @contact.save flash[:notice] = "Successfully created contact." redirect_to @contact else render :action => 'new' end end def edit @contact = Contact.find(params[:id]) @campaigns = Campaign.find(:all, :order => "name") end Here is a snippet of my error console: I am POSTING the attribute, but it is not CREATING in the Address table.... Processing ContactsController#create (for 127.0.0.1 at 2010-05-12 21:16:17) [POST] Parameters: {"commit"="Submit", "authenticity_token"="d8/gx0zy0Vgg6ghfcbAYL0YtGjYIUC2b1aG+dDKjuSs=", "contact"={"company_name"="Allyforce", "title"="", "campaign_id"="2", "address_attributes"={"street1"="abc"}, "fax"="", "phone"="", "last_name"="", "date_entered"="2010-05-12", "email"="", "first_name"="abc"}} Company Load (0.0ms)[0m [0mSELECT * FROM "companies" WHERE ("companies"."name" = 'Allyforce') LIMIT 1[0m Address Create (16.0ms)[0m [0;1mINSERT INTO "addresses" ("city", "zip", "created_at", "street1", "updated_at", "street2", "state") VALUES(NULL, NULL, '2010-05-13 04:16:18', NULL, '2010-05-13 04:16:18', NULL, NULL)[0m Contact Create (0.0ms)[0m [0mINSERT INTO "contacts" ("company", "created_at", "title", "updated_at", "campaign_id", "address_id", "last_name", "phone", "fax", "company_id", "date_entered", "first_name", "email") VALUES(NULL, '2010-05-13 04:16:18', '', '2010-05-13 04:16:18', 2, 2, '', '', '', 5, '2010-05-12', 'abc', '')[0m

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  • Why ruby has to_s and inspect?

    - by prosseek
    The p calls inspect, and puts/print calls to_s for representing its object. If I run class Graph def initialize @nodeArray = Array.new @wireArray = Array.new end def to_s # called with print / puts "Graph : #{@nodeArray.size}" end def inspect # called with p "G" end end if __FILE__ == $0 gr = Graph.new p gr print gr puts gr end I get G Graph : 0Graph : 0 Then, why does ruby has two functions do the same thing? What makes the difference between to_s and inspect? If I comment out the to_s or inspect function, I get as follows. ##

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  • How do you kill a PTY.spawn call in Ruby?

    - by viatropos
    If I run a command like this, using ruby's pty class, how do I kill it if I find a certain input string? cmd = "appcfg.py update cdn" PTY.spawn("#{cmd} 2>&1") do | input, output, pid | begin input.expect("Email:") do output.write("#{credentials[:username]}\n") end input.expect("Password:") do output.write("#{credentials[:password]}\n") end if input.gets == "SOMETHING" EXIT! end rescue Exception => e puts "GAE Error..." end end What is the right way to do that?

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  • Re-Include Module

    - by Nino55
    Hello, I need some like this: module One def test; puts 'Test One'; end end module Two def test; puts 'Test Two'; end end class Foo include One include Two include One end In this case I need as a result 'Test One' but obviously it returns 'Test Two'. I need a clean simple way for re-include my module. Any suggestion? Thanks!

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  • Rails & Twilio: Receiving nil when storing texts received from Twilio

    - by Jon Smooth
    I have set up the request URL in my Twilio account to have it POST to: myurl.com/receivetext. It appears to be successfully posting because when I check the database using the Heroku console I see the following: Post id: 5, body: nil, from: nil, created_at: "2012-06-14 17:28:01", updated_at: "2012-06-14 17:28:01" Why is it receiving nil for the body and from attributes? I can't figure out what I'm doing wrong! The created and updated at are storing successfully but the two attributes that I care about continue to be stored as nil. Here's the Receive Text controller which is receiving the Post request from Twilio: class ReceiveTextController < ApplicationController def index @post=Post.create!(body: params[:Body], from: params[:From]) end end EDIT: When I dump the params I receive the following: "{\"controller\"=\"receive_text\", \"action\"=\"index\"}" I attained this by inserting the following into my ReceiveText controller. @params = Post.create!(body: params.inspect, from: "Dumping Params") and then opening up the Heroku console to find the database entry with from = "Dumping Params". I simulated a Twilio request with a curl with the following command curl -X POST myurl.com/receivetext route -d 'AccountSid=AC123&From=%2B19252411234' I checked the production database again and noticed that the curl request did work when obtaining the FROM atribute. It stored the following: params.inspect returned "{\"AccountSid\"=\"AC123\", \"From\"=\"+19252411234\", \"co..." I received a comment stating: "As long as twilio is hitting the same URL with the same method (GET/POST) it should be filling the params array as well" I have no idea how to make this comment actionable. Any help would be greatly appreciated! I'm very new to rails. Here's my database migration (I have both attributes set to string. I have tried setting it to text and that didn't work either) : class CreatePosts < ActiveRecord::Migration def change create_table :posts do |t| t.string :body t.string :from t.timestamps end end end Here is my Post model: class Post < ActiveRecord::Base attr_accessible :body, :from end Routes (everything appears to be routing just fine) : MovieApp::Application.routes.draw do get "receive_text/index" get "pages/home" get "send_text/send_text_message" root to: 'pages#home' match '/receivetext', to: 'receive_text#index' match '/pages/home', to: 'pages#home' match '/sendtext', to: 'send_text#send_text_message' end Here's my gemfile (incase it helps) source 'https://rubygems.org' gem 'rails', '3.2.3' gem 'badfruit' gem 'twilio-ruby' gem 'logger' gem 'jquery-rails' group :production do gem 'pg' end group :development, :test do gem 'sqlite3' end group :assets do gem 'sass-rails', '~> 3.2.3' gem 'coffee-rails', '~> 3.2.1' gem 'uglifier', '>= 1.0.3' end

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  • Stepping into Ruby Meta-Programming: Generating proxy methods for multiple internal methods

    - by mstksg
    Hi all; I've multiply heard Ruby touted for its super spectacular meta-programming capabilities, and I was wondering if anyone could help me get started with this problem. I have a class that works as an "archive" of sorts, with internal methods that process and output data based on an input. However, the items in the archive in the class itself are represented and processed with integers, for performance purposes. The actual items outside of the archive are known by their string representation, which is simply number_representation.to_s(36). Because of this, I have hooked up each internal method with a "proxy method" that converts the input into the integer form that the archive recognizes, runs the internal method, and converts the output (either a single other item, or a collection of them) back into strings. The naming convention is this: internal methods are represented by _method_name; their corresponding proxy method is represented by method_name, with no leading underscore. For example: class Archive ## PROXY METHODS ## ## input: string representation of id's ## output: string representation of id's def do_something_with id result = _do_something_with id.to_i(36) return nil if result == nil return result.to_s(36) end def do_something_with_pair id_1,id_2 result = _do_something_with_pair id_1.to_i(36), id_2.to_i(36) return nil if result == nil return result.to_s(36) end def do_something_with_these ids result = _do_something_with_these ids.map { |n| n.to_i(36) } return nil if result == nil return result.to_s(36) end def get_many_from id result = _get_many_from id return nil if result == nil # no sparse arrays returned return result.map { |n| n.to_s(36) } end ## INTERNAL METHODS ## ## input: integer representation of id's ## output: integer representation of id's def _do_something_with id # does something with one integer-represented id, # returning an id represented as an integer end def do_something_with_pair id_1,id_2 # does something with two integer-represented id's, # returning an id represented as an integer end def _do_something_with_these ids # does something with multiple integer ids, # returning an id represented as an integer end def _get_many_from id # does something with one integer-represented id, # returns a collection of id's represented as integers end end There are a couple of reasons why I can't just convert them if id.class == String at the beginning of the internal methods: These internal methods are somewhat computationally-intensive recursive functions, and I don't want the overhead of checking multiple times at every step There is no way, without adding an extra parameter, to tell whether or not to re-convert at the end I want to think of this as an exercise in understanding ruby meta-programming Does anyone have any ideas? edit The solution I'd like would preferably be able to take an array of method names @@PROXY_METHODS = [:do_something_with, :do_something_with_pair, :do_something_with_these, :get_many_from] iterate through them, and in each iteration, put out the proxy method. I'm not sure what would be done with the arguments, but is there a way to test for arguments of a method? If not, then simple duck typing/analogous concept would do as well.

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  • Metaprogramming ActiveRecord Rails

    - by Dimitar Vouldjeff
    Hi, I have the following code in my project`s lib directory module Pasta module ClassMethods def self.has_coordinates self.send :include, InstanceMethods end end module InstanceMethods def coordinates [longitude ||= 43.0, latitude ||= 25.0] end end ActiveRecord::Base.extend ClassMethods end And it should create a class method for ActiveRecord::Base - has_coordinates - which I can "assign" to models... But I receive the error undefined local variable or method 'has_coordinates' Thanks in advance!

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  • Multi-threaded Application with Readonly Properties

    - by Shiftbit
    Should my multithreaded application with read only properties require locking? Since nothing is being written I assume there is no need for locks, but I would like to make sure. Would the answer to this question be language agnostic? Without Lock: Private m_strFoo as new String = "Foo" Public ReadOnly Property Foo() As String Get return m_strFoo.copy() End Get End Property With Lock: Private m_strBar as new String = "Bar" Public ReadOnly Property Bar() As String Get SyncLock (me) return m_strBar.copy() End Synclock End Get End Property

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  • Shared/Static Variable Should Be Nothing but Isn't - what gives?

    - by Denis
    I have the following code: Public Class TestClass Public Sub Test() If theGlobal IsNot Nothing Then Throw New Exception("What gives!") End Sub Private Shared theGlobal As Object = Nothing Private Shared ReadOnly Property Global Get If theGlobal Is Nothing Then theGlobal = New Object() End If Return theGlobal End Get End Property End Class Am stumped... Why is theGlobal object NOT Nothing?

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  • Support for IMAP IDLE in ruby

    - by Asaxena
    Ok, I have been suck on it for hours. I thought net/imap.rb with ruby 1.9 supported the idle command, but not yet. Can anyone help me in implementing that? From here, I though this would work: class Net::IMAP def idle cmd = "IDLE" synchronize do tag = generate_tag put_string(tag + " " + cmd) put_string(CRLF) end end def done cmd = "DONE" synchronize do put_string(cmd) put_string(CRLF) end end end But imap.idle with that just return nil.

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  • How to merge two test into one RSpec

    - by thefonso
    Both the last two test work individually...but when both are set to run (non pending) I get problems. question: can I create a test that merges the two into one? How would this look?(yes, I am new to rspec) require_relative '../spec_helper' # the universe is vast and infinite....and...it is empty describe "tic tac toe game" do context "the game class" do before (:each) do player_h = Player.new("X") player_c = Player.new("O") @game = Game.new(player_h, player_c) end it "method drawgrid must return a 3x3 game grid" do @game.drawgrid.should eq("\na #{$thegrid[:a1]}|#{$thegrid[:a2]}|#{$thegrid[:a3]} \n----------\nb #{$thegrid[:b1]}|#{$thegrid[:b2]}|#{$thegrid[:b3]} \n----------\nc #{$thegrid[:c1]}|#{$thegrid[:c2]}|#{$thegrid[:c3]} \n----------\n 1 2 3 \n") @game.drawgrid end #FIXME - last two test here - how to merge into one? it "play method must display 3x3 game grid" do STDOUT.should_receive(:puts).and_return("\na #{$thegrid[:a1]}|#{$thegrid[:a2]}|#{$thegrid[:a3]} \n----------\nb #{$thegrid[:b1]}|#{$thegrid[:b2]}|#{$thegrid[:b3]} \n----------\nc #{$thegrid[:c1]}|#{$thegrid[:c2]}|#{$thegrid[:c3]} \n----------\n 1 2 3 \n").with("computer move") @game.play end it "play method must display 3x3 game grid" do STDOUT.should_receive(:puts).with("computer move") @game.play end end end just for info here is the code containing the play method require_relative "player" # #Just a Tic Tac Toe game class class Game #create players def initialize(player_h, player_c) #bring into existence the board and the players @player_h = player_h @player_c = player_c #value hash for the grid lives here $thegrid = { :a1=>" ", :a2=>" ", :a3=>" ", :b1=>" ", :b2=>" ", :b3=>" ", :c1=>" ", :c2=>" ", :c3=>" " } #make a global var for drawgrid which is used by external player class $gamegrid = drawgrid end #display grid on console def drawgrid board = "\n" board << "a #{$thegrid[:a1]}|#{$thegrid[:a2]}|#{$thegrid[:a3]} \n" board << "----------\n" board << "b #{$thegrid[:b1]}|#{$thegrid[:b2]}|#{$thegrid[:b3]} \n" board << "----------\n" board << "c #{$thegrid[:c1]}|#{$thegrid[:c2]}|#{$thegrid[:c3]} \n" board << "----------\n" board << " 1 2 3 \n" return board end #start the game def play #draw the board puts drawgrid #external call to player class @player = @player_c.move_computer("O") end end player_h = Player.new("X") player_c = Player.new("O") game = Game.new(player_h, player_c) game.play

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  • C++ STL: Trouble with iterators

    - by Rosarch
    I'm having a beginner problem: bool _isPalindrome(const string& str) { return _isPalindrome(str.begin(), str.end()); // won't compile } bool _isPalindrome(string::iterator begin, string::iterator end) { return begin == end || *begin == *end && _isPalindrome(++begin, --end); } What am I doing wrong here? Why doesn't str.begin() get type checked to be a string::iterator?

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  • Model def in View State

    - by tinzawtun
    In my ruby on rails project in model, I have some of definition. class PlaySport < ActiveRecord::Base belongs_to :user belongs_to :sport def self.getLevel end def self.check_play_sport(cuser_id,sport_id) end def current_playing_sport end def all_played_sports end end I catch for this relation like this current_user.play_sports.current_playing_sport But I get the undefined method error "current_playing_sports" What is wrong

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  • Rails: i have a class method and i want to modify something of the instance

    - by Totty
    Rails: i have a class method and i want to modify something of the instance something like this: class Test < Main template :box def test # here I want to access the template name, that is box end end class Main def initialize end def self.template(name) # here I have to save somehow the template name # remember is not an instance. end end that is similar to the model classes: # in the model has_many :projects How do I do it?

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  • AS11 Oracle B2B Sync Support - Series 1

    - by sinkarbabu.kirubanithi
    Synchronous message support has been enabled in Oracle B2B 11G. This would help customers to send the business message and receive the corresponding business response synchronously. We would like to keep this blog entry as three part series, first one would carry Oracle B2B configuration related details followed by 'how it can be consumed and utilized in an enterprise' using composites backed model. And, the last one would talk about more sophisticated seeded support built on Oracle B2B platform (Note: the last one is still in description phase and ETA hasn't been finalized yet). Details: In an effort to enable synchronous processing in Oracle B2B, we provided a platform using the existing 'callout' mechanism. In this case, we expect the 'callout' attached to the agreement to deliver incoming business message (inbound) to back-end application and get the corresponding business response from back-end and deliver it to Oracle B2B as its output. The output of 'callout' would be processed as outbound message and the same will be attached as a response for the inbound message. Requirements to enable Sync Support: Outbound side: Outbound Agreement - to send business message request Inbound Agreement - to receive business message response Inbound side: Inbound Agreement - to receive business message request Outbound Agreement - to send business message response Agreement Level Callout - to deliver the inbound request to back-end and get the corresponding business response This feature is supported only for HTTP based transport to exchange messages with Trading Partners. One may initiate the outbound message (enqueue) using any of the available Transports in Oracle B2B. Configuration: Outbound side: Please add "syncresponse=true" as "Additional Transport Header" parameter for remote Trading Partner's HTTP delivery channel configuration. This would enable Oracle B2B to process the HTTP response as inbound message and deliver the same to back-end application. All other configuration related to Agreement and Document setup remain same. Inbound side: There is no change in Agreement and Document setup. To enable "Sync Support", you need to build a 'callout' that takes the responsibility of delivering inbound message to back-end and get the corresponding business response from the back-end and attach the same as its output. Oracle B2B treats the output of 'callout' as outbound message and deliver it to Trading Partner as synchronous HTTP response. The requests that needs to processed synchronously should be received by "syncreceiver" (http://:/b2b/syncreceiver) endpoint in Oracle B2B. Exception Handling: Existing Oracle B2B exception handling applies to this use case as well. Here's the sample callout, SampleSyncCallout.java We will get you second part that talks about 'SOA composites' backed model to design the "Sync Support" use case from back-end to Trading Partners, stay tuned.

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  • Advice Needed: Developers blocked by waiting on code to merge from another branch using GitFlow

    - by fogwolf
    Our team just made the switch from FogBugz & Kiln/Mercurial to Jira & Stash/Git. We are using the Git Flow model for branching, adding subtask branches off of feature branches (relating to Jira subtasks of Jira features). We are using Stash to assign a reviewer when we create a pull request to merge back into the parent branch (usually develop but for subtasks back into the feature branch). The problem we're finding is that even with the best planning and breakdown of feature cases, when multiple developers are working together on the same feature, say on the front-end and back-end, if they are working on interdependent code that is in separate branches one developer ends up blocking the other. We've tried pulling between each others' branches as we develop. We've also tried creating local integration branches each developer can pull from multiple branches to test the integration as they develop. Finally, and this seems to work possibly the best for us so far, though with a bit more overhead, we have tried creating an integration branch off of the feature branch right off the bat. When a subtask branch (off of the feature branch) is ready for a pull request and code review, we also manually merge those change sets into this feature integration branch. Then all interested developers are able to pull from that integration branch into other dependent subtask branches. This prevents anyone from waiting for any branch they are dependent upon to pass code review. I know this isn't necessarily a Git issue - it has to do with working on interdependent code in multiple branches, mixed with our own work process and culture. If we didn't have the strict code-review policy for develop (true integration branch) then developer 1 could merge to develop for developer 2 to pull from. Another complication is that we are also required to do some preliminary testing as part of the code review process before handing the feature off to QA.This means that even if front-end developer 1 is pulling directly from back-end developer 2's branch as they go, if back-end developer 2 finishes and his/her pull request is sitting in code review for a week, then front-end developer 2 technically can't create his pull request/code review because his/her code reviewer can't test because back-end developer 2's code hasn't been merged into develop yet. Bottom line is we're finding ourselves in a much more serial rather than parallel approach in these instance, depending on which route we go, and would like to find a process to use to avoid this. Last thing I'll mention is we realize by sharing code across branches that haven't been code reviewed and finalized yet we are in essence using the beta code of others. To a certain extent I don't think we can avoid that and are willing to accept that to a degree. Anyway, any ideas, input, etc... greatly appreciated. Thanks!

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  • jQuery: Novice to Ninja

    <b>A Million Chimpanzees:</b> "Who should read this book? There was the usual blurb in the book's front matter about "If you're a front-end web designer looking to..." which I expected, but what are the minimal qualifications the reader should have before shelling out his or her hard earned dough for this text?"

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  • Enabling unattended-upgrades from a shell script

    - by Grant Watson
    I have a shell script to automatically configure new Ubuntu virtual machines for my purposes. I would like this script to install and enable unattended-upgrades, but I cannot figure out how to do so without user interaction. The usual way to enable upgrades is dpkg-reconfigure unattended-upgrades, but of course that is interactive. The noninteractive front end avoids asking any questions at all, and the text front end seems bound and determined to do its I/O with the tty and not with stdin/stdout.

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  • Mobile Apps: An Ongoing Revolution

    - by Steve Walker
    a guest post from Suhas Uliyar, VP Mobile Strategy, Product Management, Oracle The rise of smartphone apps have proved transformational for businesses, increasing the productivity of employees while simultaneously creating some seriously cool end user experiences. But this is a revolution that is only just beginning. Over the next few years, apps will change everything about the way enterprises work as well as overhauling the experiences of customers. The spark for this revolution is simplicity. Simplicity has already proved important for the front-end of apps, which are now often as compelling and intuitive as consumer apps. Businesses will encourage this trend, both to further increase employee productivity and to attract ‘digital natives’ (as employees and customers). With the variety of front-end development tools available already, this should be a simple mission for developers to accomplish – but front-end simplicity alone is not enough for the enterprise mobile revolution. Without the right content even the most user-friendly app is useless. Yet when it comes to integrating apps with ‘back-end’ systems to enable this content, developers often face a complex, costly and time-consuming task. Then there is security: how can developers strike a balance between complying with enterprise security policies and keeping the user experience simple? Complexity has acted as a brake on innovation, with integration and security compliance swallowing enterprise resources. This is why the simplification of integration, security and scalability is so important: it frees time and money for revolutionary innovation. The key is to put in place a complete and unified SOA integration platform that runs across the entire enterprise and enables organizations to easily integrate and connect applications across IT environments. The platform must also be capable of abstracting apps from the underlying OS and enabling a ‘write-once, run- anywhere’ capability for mobile devices - essential for BYOD environments and integrating third-party apps. Mobile Back-end-as-a-Service can also be very important in streamlining back-end integration. Mobile services offered through the cloud can simplify mobile application development with a standard approach to dealing with complex server-side programming and integration issues. This allows the business to innovate at its own pace while providing developers with a choice of tools to speed development and integration. Finally, there is security, which must be done in a way that encourages users to make the most of their mobile devices and applications. As mobile users, we want convenience and that is why we generally approve of businesses that adopt BYOD policies. Enterprises can safely encourage BYOD as they can separate, protect, and wipe corporate applications by installing a secure ‘container’ around corporate applications on any mobile device. BYOD management also means users’ personal applications and data can be kept separate from the enterprise information – giving them the confidence they need to embrace the use of their devices for corporate apps. Enterprises that place mobility at the heart of what they do will fundamentally transform their businesses and leap ahead of the competition. As businesses take to mobile platforms that simplify integration, security and scalability we will see a blossoming of innovation that will drive new levels of user convenience and create new ways of working that we are only beginning to imagine.

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  • blender: 3D model from guide images

    - by Stefan
    In a effort to learn the blender interface, which is confusing to say the least, I've chosen to model a model from referrence pictures easily found on the web. Problem is that I can't ( and won't ) get perfect "right", "front" and "top" pictures. Blender only allows you to see the background pictures when in ortographic mode and only from right|front|top, which doesn't help me. How to I proceed to model from non-perfect guide images?

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  • Merge sort versus quick sort performance

    - by Giorgio
    I have implemented merge sort and quick sort using C (GCC 4.4.3 on Ubuntu 10.04 running on a 4 GB RAM laptop with an Intel DUO CPU at 2GHz) and I wanted to compare the performance of the two algorithms. The prototypes of the sorting functions are: void merge_sort(const char **lines, int start, int end); void quick_sort(const char **lines, int start, int end); i.e. both take an array of pointers to strings and sort the elements with index i : start <= i <= end. I have produced some files containing random strings with length on average 4.5 characters. The test files range from 100 lines to 10000000 lines. I was a bit surprised by the results because, even though I know that merge sort has complexity O(n log(n)) while quick sort is O(n^2), I have often read that on average quick sort should be as fast as merge sort. However, my results are the following. Up to 10000 strings, both algorithms perform equally well. For 10000 strings, both require about 0.007 seconds. For 100000 strings, merge sort is slightly faster with 0.095 s against 0.121 s. For 1000000 strings merge sort takes 1.287 s against 5.233 s of quick sort. For 5000000 strings merge sort takes 7.582 s against 118.240 s of quick sort. For 10000000 strings merge sort takes 16.305 s against 1202.918 s of quick sort. So my question is: are my results as expected, meaning that quick sort is comparable in speed to merge sort for small inputs but, as the size of the input data grows, the fact that its complexity is quadratic will become evident? Here is a sketch of what I did. In the merge sort implementation, the partitioning consists in calling merge sort recursively, i.e. merge_sort(lines, start, (start + end) / 2); merge_sort(lines, 1 + (start + end) / 2, end); Merging of the two sorted sub-array is performed by reading the data from the array lines and writing it to a global temporary array of pointers (this global array is allocate only once). After each merge the pointers are copied back to the original array. So the strings are stored once but I need twice as much memory for the pointers. For quick sort, the partition function chooses the last element of the array to sort as the pivot and scans the previous elements in one loop. After it has produced a partition of the type start ... {elements <= pivot} ... pivotIndex ... {elements > pivot} ... end it calls itself recursively: quick_sort(lines, start, pivotIndex - 1); quick_sort(lines, pivotIndex + 1, end); Note that this quick sort implementation sorts the array in-place and does not require additional memory, therefore it is more memory efficient than the merge sort implementation. So my question is: is there a better way to implement quick sort that is worthwhile trying out? If I improve the quick sort implementation and perform more tests on different data sets (computing the average of the running times on different data sets) can I expect a better performance of quick sort wrt merge sort? EDIT Thank you for your answers. My implementation is in-place and is based on the pseudo-code I have found on wikipedia in Section In-place version: function partition(array, 'left', 'right', 'pivotIndex') where I choose the last element in the range to be sorted as a pivot, i.e. pivotIndex := right. I have checked the code over and over again and it seems correct to me. In order to rule out the case that I am using the wrong implementation I have uploaded the source code on github (in case you would like to take a look at it). Your answers seem to suggest that I am using the wrong test data. I will look into it and try out different test data sets. I will report as soon as I have some results.

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  • Enable grub boot menu on new system

    - by Remus Rigo
    I have installed Ubuntu 11.04 and I would like to see the boot menu when the system starts (by default it is hidden or the timeout=0) # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm fi terminal_output gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext if [ "${recordfail}" = 1 ]; then set timeout=-1 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 insmod jpeg if background_image /boot/grub/boot.jpg; then true else set menu_color_normal=white/black set menu_color_highlight=black/light-gray fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 2.6.38-8-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 linux /boot/vmlinuz-2.6.38-8-generic root=UUID=44f311b4-0b40-4d10-b004-78108539fc39 ro quiet splash vt.handoff=7 initrd /boot/initrd.img-2.6.38-8-generic } menuentry 'Ubuntu, with Linux 2.6.38-8-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 echo 'Loading Linux 2.6.38-8-generic ...' linux /boot/vmlinuz-2.6.38-8-generic root=UUID=44f311b4-0b40-4d10-b004-78108539fc39 ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.38-8-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 44f311b4-0b40-4d10-b004-78108539fc39 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### if [ "x${timeout}" != "x-1" ]; then if keystatus; then if keystatus --shift; then set timeout=-1 else set timeout=0 fi else if sleep --interruptible 3 ; then set timeout=0 fi fi fi ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ###

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  • How to resize / enlarge / grow a non-LVM ext4 partition

    - by Mischa
    I have already searched the forums, but couldnt find a good suitable answer: I have an Ubuntu Server 10.04 as KVM Host and a guest system, that also runs 10.04. The host system uses LVM and there are three logical volumes, which are provided to the guest as virtual block devices - one for /, one for /home and one for swap. The guest had been partitioned without LVM. I have already enlarged the logical volume in the host system - the guest successfully sees the bigger virtual disk. However, this virtual disk contains one "good old" partition, which still has the old small size. The output of fdisk -l is me@produktion:/$ LC_ALL=en_US sudo fdisk -l Disk /dev/vda: 32.2 GB, 32212254720 bytes 255 heads, 63 sectors/track, 3916 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000c8ce7 Device Boot Start End Blocks Id System /dev/vda1 * 1 3917 31455232 83 Linux Disk /dev/vdb: 2147 MB, 2147483648 bytes 244 heads, 47 sectors/track, 365 cylinders Units = cylinders of 11468 * 512 = 5871616 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000f2bf7 Device Boot Start End Blocks Id System /dev/vdb1 1 366 2095104 82 Linux swap / Solaris Partition 1 has different physical/logical beginnings (non-Linux?): phys=(0, 32, 33) logical=(0, 43, 28) Partition 1 has different physical/logical endings: phys=(260, 243, 47) logical=(365, 136, 44) Disk /dev/vdc: 225.5 GB, 225485783040 bytes 255 heads, 63 sectors/track, 27413 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00027f25 Device Boot Start End Blocks Id System /dev/vdc1 1 9138 73398272 83 Linux The output of parted print all is Model: Virtio Block Device (virtblk) Disk /dev/vda: 32.2GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 1049kB 32.2GB 32.2GB primary ext4 boot Model: Virtio Block Device (virtblk) Disk /dev/vdb: 2147MB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 1049kB 2146MB 2145MB primary linux-swap(v1) Model: Virtio Block Device (virtblk) Disk /dev/vdc: 225GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 1049kB 75.2GB 75.2GB primary ext4 What I want to achieve is to simply grow or resize the partition /dev/vdc1 so that it uses the whole space provided by the virtual block device /dev/vdc. The problem is, that when I try to do that with parted, it complains: (parted) select /dev/vdc Using /dev/vdc (parted) print Model: Virtio Block Device (virtblk) Disk /dev/vdc: 225GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 1049kB 75.2GB 75.2GB primary ext4 (parted) resize 1 WARNING: you are attempting to use parted to operate on (resize) a file system. parted's file system manipulation code is not as robust as what you'll find in dedicated, file-system-specific packages like e2fsprogs. We recommend you use parted only to manipulate partition tables, whenever possible. Support for performing most operations on most types of file systems will be removed in an upcoming release. Start? [1049kB]? End? [75.2GB]? 224GB Error: File system has an incompatible feature enabled. Compatible features are has_journal, dir_index, filetype, sparse_super and large_file. Use tune2fs or debugfs to remove features. So what can I do? This is a headless production system. What is a safe way to grow this partition? I CAN unmount it, though - so this is not the problem.

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  • BizTalk&ndash;Mapping repeating EDI segments using a Table Looping functoid

    - by Bill Osuch
    BizTalk’s HIPAA X12 schemas have several repeating date/time segments in them, where the XML winds up looking something like this: <DTM_StatementDate> <DTM01_DateTimeQualifier>232</DTM01_DateTimeQualifier> <DTM02_ClaimDate>20120301</DTM02_ClaimDate> </DTM_StatementDate> <DTM_StatementDate> <DTM01_DateTimeQualifier>233</DTM01_DateTimeQualifier> <DTM02_ClaimDate>20120302</DTM02_ClaimDate> </DTM_StatementDate> The corresponding EDI segments would look like this: DTM*232*20120301~ DTM*233*20120302~ The DateTimeQualifier element indicates whether it’s the start date or end date – 232 for start, 233 for end. So in this example (an X12 835) we’re saying the statement starts on 3/1/2012 and ends on 3/2/2012. When you’re mapping from some other data format, many times your start and end dates will be within the same node, like this: <StatementDates> <Begin>20120301</Begin> <End>20120302</End> </StatementDates> So how do you map from that and create two repeating segments in your destination map? You could connect both the <Begin> and <End> nodes to a looping functoid, and connect its output to <DTM_StatementDate>, then connect both <Begin> and <End> to <DTM_StatementDate> … this would give you two repeating segments, each with the correct date, but how to add the correct qualifier? The answer is the Table Looping Functoid! To test this, let’s create a simplified schema that just contains the date fields we’re mapping. First, create your input schema: And your output schema: Now create a map that uses these two schemas, and drag a Table Looping functoid onto it. The first input parameter configures the scope (or how many times the records will loop), so drag a link from the StatementDates node over to the functoid. Yes, StatementDates only appears once, so this would make it seem like it would only loop once, but you’ll see in just a minute. The second parameter in the functoid is the number of columns in the output table. We want to fill two fields, so just set this to 2. Now drag the Begin and End nodes over to the functoid. Finally, we want to add the constant values for DateTimeQualifier, so add a value of 232 and another of 233. When all your inputs are configured, it should look like this: Now we’ll configure the output table. Click on the Table Looping Grid, and configure it to look like this: Microsoft’s description of this functoid says “The Table Looping functoid repeats with the looping record it is connected to. Within each iteration, it loops once per row in the table looping grid, producing multiple output loops.” So here we will loop (# of <StatementDates> nodes) * (Rows in the table), or 2 times. Drag two Table Extractor functoids onto the map; these are what are going to pull the data we want out of the table. The first input to each of these will be the output of the TableLooping functoid, and the second input will be the row number to pull from. So the functoid connected to <DTM01_DateTimeQualifier> will look like this: Connect these two functoids to the two nodes we want to populate, and connect another output from the Table Looping functoid to the <DTM_StatementDate> record. You should have a map that looks something like this: Create some sample xml, use it as the TestMap Input Instance, and you should get a result like the XML at the top of this post. Technorati Tags: BizTalk, EDI, Mapping

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