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• Learning OO for a C Programmer

  - by Holysmoke

  I've been programming professionally in C, and only C, for around 10 years in a variety of roles. As would be normal to expect, I understand the idioms of the language fairly well and beyond that also some of the design nuances - which APIs to make public, who calls what, who does what, what is supposed to reentrant and so on. I grew up reading 'Writing Solid Code', it's early C edition, not the one based on C++. However, I've never ever programmed in an OO language. Now, I want to migrate to writing applications for iPhone (maybe android), so want to learn to use Objective-C and use it with a degree of competence fitting a professional programmer. How do I wrap my head around the OO stuff? What would be your smallest reading list suggestion to me. Is there a book that carries some sort of relatively real world example OO design Objective-C? Besides, the reading what source code would you recommend me to go through. How to learn OO paradigm using Objective-C?

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• Exchange 2007 - Mailbox Database Recovery

  - by Phrontiste

  Exchange 2007 edb Can we restore Exchange edb (First storage group\mailbox database.edb) to another exchange server ? Do I just copy the edb to the new exchange server and delete the first storage group\mailbox database.edb and replace it with this one ? How can I get all the mailboxes from that (old) mailbox database.edb ? I had a exchange 2007 server with 10 mailboxes, I have installed exchange on another machine and was thinking if I can do the above ? or is there any way I can get all the mailboxes from that edb (old mailbox database) and import them into the new one. I have deleted the old exchange install I had (these are test machines) What are the steps required to get the DB working on the new machine ? Also, I am confused about the recovery storage group ? I can mount a mailbox database in recovery storage group, but when I try to get mailbox out of it, it won't match any thing ? can someone please assist in understanding RSG and how to restore the OLD mailbox database. thanks and regards Phrontiste

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• Setting up ASP.NET structure for code

  - by user1175327

  I've always coded in C# MVC3 when developing web applications. But now i wanted to learn a bit more about developing web sites with just ASP.NET. But now i'm wondering what a good setup for my code would be. For me, an MVC like pattern seems to be a good way to go. But obviously ASP.NET doesn't have any router and controller classes. So i guess people have a different way of setting up their code when they do ASP.NET. So i'm looking for more information on how to get started with this. So not really the basics of ASP.NET, but something that focuses on a good code setup. Any good tutorials/information about this/?

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• Mapping Object Relationships - QuickStart with NHibernate (Part 3)

  - by BobPalmer

  For this third tutorial, we'll be introducing users new to NHibernat to basic object relationships, starting with a simple many-to-one relationship.  I decided that it would make sense to at least get the readers through some basic relationship mapping (including varieties of parent/child and many to many relationships) before diverging into UI, since most folks are looking for enough to bootstrap themsevles into using NHibernate, and this almost always means some kind of relation between their objects. You can find a link to the article at: http://docs.google.com/Doc?docid=0AUP-rKyyUMKhZGczejdxeHZfMjJmM3c3M3Bnbg&hl=en As always, comments, corrections, and suggestions are appreciated! -Bob

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• Law of Demeter confusion [duplicate]

  - by user2158382

  This question already has an answer here: Rails: Law of Demeter Confusion 4 answers I am reading a book called Rails AntiPatterns and they talk about using delegation to to avoid breaking the Law of Demeter. Here is their prime example: They believe that calling something like this in the controller is bad (and I agree) @street = @invoice.customer.address.street Their proposed solution is to do the following: class Customer has_one :address belongs_to :invoice def street address.street end end class Invoice has_one :customer def customer_street customer.street end end @street = @invoice.customer_street They are stating that since you only use one dot, you are not breaking the Law of Demeter here. I think this is incorrect, because you are still going through customer to go through address to get the invoice's street. I primarily got this idea from a blog post I read: http://www.dan-manges.com/blog/37 In the blog post the prime example is class Wallet attr_accessor :cash end class Customer has_one :wallet # attribute delegation def cash @wallet.cash end end class Paperboy def collect_money(customer, due_amount) if customer.cash < due_ammount raise InsufficientFundsError else customer.cash -= due_amount @collected_amount += due_amount end end end The blog post states that although there is only one dot customer.cash instead of customer.wallet.cash, this code still violates the Law of Demeter. Now in the Paperboy collect_money method, we don't have two dots, we just have one in "customer.cash". Has this delegation solved our problem? Not at all. If we look at the behavior, a paperboy is still reaching directly into a customer's wallet to get cash out. Can somebody help me clear the confusion. I have been searching for the past 2 days trying to let this topic sink in, but it is still confusing.

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• how should I design Objects around this business requirement?

  - by brainydexter

  This is the business requirement: " A Holiday Package (e.g. New York NY Holiday Package) can be offered in different ways based on the Origin city: From New Delhi to NY From Bombay to NY NY itself ( Land package ) (Bold implies default selection) a. and b. User can fly from either New Delhi or Bombay to NY. c. NY is a Land package, where a user can reach NY by himself and is a standalone holidayPackage. " Let's say I have a class that represents HolidayPackage, Destination (aka City). public class HolidayPackage{ Destination holidayCity; ArrayList<BaseHolidayPackageVariant> variants; BaseHolidayPackageVariant defaultVariant; } public abstract class BaseHolidayPackageVariant { private Integer variantId; private HolidayPackage holidayPackage; private String holidayPackageType; } public class LandHolidayPackageVariant extends BaseHolidayPackageVariant{ } public class FlightHolidayPackageVariant extends BaseHolidayPackageVariant{ private Destination originCity; } What data structure/objects should I design to support: options a default within those options Sidenote: A HolidayPackage can also be offered in different ways based on Hotel selections. I'd like to follow a design which I can leverage to support that use case in the future. This is the backend design I have in mind.

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• Is there a good design pattern for this messaging class?

  - by salonMonsters

  Is there a good design pattern for this? I want to create a messaging class. The class will be passed: the type of message (eg. signup, signup confirmation, password reminder etc) the client's id The class needs to then look up the client's messaging preferences in the db (whether they want communication by email, sms or both) Then depending on the client's preference it will format the message for the medium (short version for sms, long form for email) and send it through our mail or sms provider's API. Because the fact that we want to be able to change out email and sms providers if need be I wondered if the Command Pattern would be a good choice.

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• Database Insider Newsletter: February 2011 Edition Available

  - by jenny.gelhausen

  The February edition of the Database Insider Newsletter is now available. This edition covers the upcoming IOUG's Day of Real World Performance Tour What's coming for Collaborate 2011 How Oracle helps you steer clear of security pitfalls and much more... Enjoy! var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); try { var pageTracker = _gat._getTracker("UA-13185312-1"); pageTracker._trackPageview(); } catch(err) {}

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• ORA- 01157 / Cant connect to database

  - by Tom

  Hi everyone, this is a follow up from this question. Let me start by saying that i am NOT a DBA, so i'm really really lost with this. A few weeks ago, we lost contact with one of our SID'S. All the other services are working, but this one in particular is not. What we got was this message when trying to connect ORA-01033: ORACLE initialization or shutdown in progress An attempt to alter database open ended up in ORA-01157: cannot identify/lock data file 6 - see DBWR trace file ORA-01110: data file 6: '/u01/app/oracle/oradata/xxx/xxx_data.dbf' I tried to shutdown / restart the database, but got this message. Total System Global Area 566231040 bytes Fixed Size 1220604 bytes Variable Size 117440516 bytes Database Buffers 444596224 bytes Redo Buffers 2973696 bytes Database mounted. ORA-01157: cannot identify/lock data file 6 - see DBWR trace file ORA-01110: data file 6: '/u01/app/oracle/oradata/xxx/xxx_data.dbf' When all continued the same, I erased the dbf files (rm xxx_data.dbf xxx_index.dbf), and recreated them using touch xxx_data.dbf. I also tried to recreate the tablespaces using `CREATE TABLESPACE DATA DATAFILE XXX_DATA.DBF` and got Database not open As I said, i don't know how bad this is, or how far i'm from gaining access to my database (well, to this SID at least, the others are working). I would imagine that a last resource would be to throw everything away, and recreating it, but I don't know how to, and I was hoping there's a less destructive solution. Any help will be greatly appreciated . Thanks in advance.

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• Oracle NoSQL Database Using FusionIO ioDrive2

  - by Charles Lamb

  We ran some benchmarks using FusionIO ioDrive2 SSD drives and Oracle NoSQL Database. FusionIO has published a whitepaper with the results of the benchmarks. "Results of testing showed that using an ioDrive2 for data delivered nearly 30 times more operations per second than a 300GB 10k SAS disk on a 90 percent read and 10 percent write workload and nearly eight times more operations per second on a 50 percent read and 50 percent write workload. Equally impressive, an ioDrive2 reduced latency over 700 percent (seven times) on inserts in a 90 percent read and 10 percent write workload and over 5800 percent (58 times) on reads in a 50 percent read and 50 percent write workload."

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• design for supporting entities with images

  - by brainydexter

  I have multiple entities like Hotels, Destination Cities etc which can contain images. The way I have my system setup right now is, I think of all the images belonging to this universal set (a table in the DB contains filePaths to all the images). When I have to add an image to an entity, I see if the entity exists in this universal set of images. If it exists, attach the reference to this image, else create a new image. E.g.: class ImageEntityHibernateDAO { public void addImageToEntity(IContainImage entity, String filePath, String title, String altText) { ImageEntity image = this.getImage(filePath); if (image == null) image = new ImageEntity(filePath, title, altText); getSession().beginTransaction(); entity.getImages().add(image); getSession().getTransaction().commit(); } } My question is: Earlier I had to write this code for each entity (and each entity would have a Set collection). So, instead of re-writing the same code, I created the following interface: public interface IContainImage { Set<ImageEntity> getImages(); } Entities which have image collections also implements IContainImage interface. Now, for any entity that needs to support adding Image functionality, all I have to invoke from the DAO looks something like this: // in DestinationDAO::addImageToDestination { imageDao.addImageToEntity(destination, imageFileName, imageTitle, imageAltText); // in HotelDAO::addImageToHotel { imageDao.addImageToEntity(hotel, imageFileName, imageTitle, imageAltText); It'd be great help if someone can provide me some critique on this design ? Are there any serious flaws that I'm not seeing right away ?

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• Should all, none, or some overridden methods call Super?

  - by JoJo

  When designing a class, how do you decide when all overridden methods should call super or when none of the overridden methods should call super? Also, is it considered bad practice if your code logic requires a mixture of supered and non-supered methods like the Javascript example below? ChildClass = new Class.create(ParentClass, { /** * @Override */ initialize: function($super) { $super(); this.foo = 99; }, /** * @Override */ methodOne: function($super) { $super(); this.foo++; }, /** * @Override */ methodTwo: function($super) { this.foo--; } }); After delving into the iPhone and Android SDKs, I noticed that super must be called on every overridden method, or else the program will crash because something wouldn't get initialized. When deriving from a template/delegate, none of the methods are supered (obviously). So what exactly are these "je ne sais quoi" qualities that determine whether a all, none, or some overriden methods should call super?

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• How to verify the Liskov substitution principle in an inheritance hierarchy?

  - by Songo

  Inspired by this answer: Liskov Substitution Principle requires that Preconditions cannot be strengthened in a subtype. Postconditions cannot be weakened in a subtype. Invariants of the supertype must be preserved in a subtype. History constraint (the "history rule"). Objects are regarded as being modifiable only through their methods (encapsulation). Since subtypes may introduce methods that are not present in the supertype, the introduction of these methods may allow state changes in the subtype that are not permissible in the supertype. The history constraint prohibits this. I was hoping if someone would post a class hierarchy that violates these 4 points and how to solve them accordingly. I'm looking for an elaborate explanation for educational purposes on how to identify each of the 4 points in the hierarchy and the best way to fix it. Note: I was hoping to post a code sample for people to work on, but the question itself is about how to identify the faulty hierarchies :)

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• Are injectable classes allowed to have constructor parameters in DI?

  - by Songo

  Given the following code: class ClientClass{ public function print(){ //some code to calculate $inputString $parser= new Parser($inputString); $result= $parser->parse(); } } class Parser{ private $inputString; public __construct($inputString){ $this->inputString=$inputString; } public function parse(){ //some code } } Now the ClientClass has dependency on class Parser. However, if I wanted to use Dependency Injection for unit testing it would cause a problem because now I can't send the input string to the parser constructor like before as its calculated inside ClientCalss itself: class ClientClass{ private $parser; public __construct(Parser $parser){ $this->parser=$parser; } public function print(){ //some code to calculate $inputString $result= $this->parser->parse(); //--> will throw an exception since no string was provided } } The only solution I found was to modify all my classes that took parameters in their constructors to utilize Setters instead (example: setInputString()). However, I think there might be a better solution than this because sometimes modifying existing classes can cause much harm than benefit. So, Are injectable classes not allowed to have input parameters? If a class must take input parameters in its constructor, what would be the way to inject it properly? UPDATE Just for clarification, the problem happens when in my production code I decide to do this: $clientClass= new ClientClass(new Parser($inputString));//--->I have no way to predict $inputString as it is calculated inside `ClientClass` itself. UPDATE 2 Again for clarification, I'm trying to find a general solution to the problem not for this example code only because some of my classes have 2, 3 or 4 parameters in their constructors not only one.

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• Java word scramble game [closed]

  - by Dan

  I'm working on code for a word scramble game in Java. I know the code itself is full of bugs right now, but my main focus is getting a vector of strings broken into two separate vectors containing hints and words. The text file that the strings are taken from has a colon separating them. So here is what I have so far. public WordApp() { inputRow = new TextInputBox(); inputRow.setLocation(200,100); phrases = new Vector <String>(FileUtilities.getStrings()); v_hints = new Vector<String>(); v_words = new Vector<String>(); textBox = new TextBox(200,100); textBox.setLocation(200,200); textBox.setText(scrambled + "\n\n Time Left: \t" + seconds/10 + "\n Score: \t" + score); hintBox = new TextBox(200,200); hintBox.setLocation(300,400); hintBox.hide(); Iterator <String> categorize = phrases.iterator(); while(categorize.hasNext()) { int index = phrases.indexOf(":"); String element = categorize.next(); v_words.add(element.substring(0,index)); v_hints.add(element.substring(index +1)); phrases.remove(index); System.out.print(index); } The FileUtilities file was given to us by the pofessor, here it is. import java.util.*; import java.io.*; public class FileUtilities { private static final String FILE_NAME = "javawords.txt"; //------------------ getStrings ------------------------- // // returns a Vector of Strings // Each string is of the form: word:hint // where word contains no spaces. // The words and hints are read from FILE_NAME // // public static Vector<String> getStrings ( ) { Vector<String> words = new Vector<String>(); File file = new File( FILE_NAME ); Scanner scanFile; try { scanFile = new Scanner( file); } catch ( IOException e) { System.err.println( "LineInput Error: " + e.getMessage() ); return null; } while ( scanFile.hasNextLine() ) { // read the word and follow it by a colon String s = scanFile.nextLine().trim().toUpperCase() + ":"; if( s.length()>1 && scanFile.hasNextLine() ) { // append the hint and add to collection s+= scanFile.nextLine().trim(); words.add(s); } } // shuffle Collections.shuffle(words); return words; } }

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• Breaking up classes and methods into smaller units

  - by micahhoover

  During code reviews a couple devs have recommended I break up my methods into smaller methods. Their justification was (1) increased readability and (2) the back trace that comes back from production showing the method name is more specific to the line of code that failed. There may have also been some colorful words about functional programming. Additionally I think I may have failed an interview a while back because I didn't give an acceptable answer about when to break things up. My inclination is that when I see a bunch of methods in a class or across a bunch of files, it isn't clear to me how they flow together, and how many times each one gets called. I don't really have a good feel for the linearity of it as quickly just by eye-balling it. The other thing is a lot of people seem to place a premium of organization over content (e.g. 'Look at how organized my sock drawer is!' Me: 'Overall, I think I can get to my socks faster if you count the time it took to organize them'). Our business requirements are not very stable. I'm afraid that if the classes/methods are very granular it will take longer to refactor to requirement changes. I'm not sure how much of a factor this should be. Anyway, computer science is part art / part science, but I'm not sure how much this applies to this issue.

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• Ruby - when to use instance variables vs parameters between methods?

  - by Michael Durrant

  I'm writing several methods that call other methods. To pass the information I have a couple of choices: Pass the information as parameters Set instance variables so that other methods can access them When should I choose one option over the other? It seems that the first option is good as it is very specific about what is being passed. the downside seems to be that a lot of values are being passed around. The second method doesn't require passing all the values around but seems to lead to a lot of magic where methods set instance variables 'somewhere' Should I always be very explicit about gets passed to other methods in the class? Are there exceptions so this?

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• Is having 'Util' classes a cause for concern? [closed]

  - by Matt Fenwick

  I sometimes create 'Util' classes which primarily serve to hold methods and values that don't really seem to belong elsewhere. But every time I create one of these classes, I think "uh-oh, I'm gonna regret this later ...", because I read somewhere that it's bad. But on the other hand, there seem to be two compelling (at least for me) cases for them: implementation secrets that are used in multiple classes within a package providing useful functionality to augment a class, without cluttering its interface Am I on the way to destruction? What you say !! Should I refactor?

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• To identify the classes for uml diagrams?

  - by user106535

  I want to implement a software engineering project based on "crime management system". The main modules are: visitors, users, administrator. The main events that are taking place are: registration, report complaint, report crime, report most wanted, view status of reported crime. So could you please help me to identify the classes that are to be used in this project and help me to draw the class diagram?

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• Jetzt anmelden: Oracle Database Security Seminare

  - by A&C Redaktion

  Die Anforderungen an Datensicherheit steigen stetig. Seit mehr als 30 Jahren verfügt Oracle über Kompetenz im Bereich der Informationssicherheit. Wenn es um handfeste Lösungen für die Datensicherheit geht, sind Sie bei uns also in den besten Händen.  Nutzen Sie die kostenlosen Database Security Seminare, um sich mit Experten von Oracle und Platinum Partner Trivadis über den Schutz Ihrer IT-Infrastruktur auszutauschen und mehr darüber zu erfahren, wie Sie Schwachstellen erkennen und welche Maßnahmen Ihnen bei der Verbesserung des Sicherheitsstatus Ihres Unternehmens helfen können. Die Plätze sind begrenzt - melden Sie sich gleich online an: 13. Juni 2012, Oracle Geschäftsstelle Hamburg 20. Juni 2012, Oracle Geschäftsstelle Stuttgart

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• How to handle status columns in designing tables

  - by altsyset

  How to handle multiple statuses for a table entry, for example an item table may have an active, inactive, fast moving, and/or batch statuses. And I wanted to handle them in single column with VARCHAR type. Also I might set each of those attributes as a boolean with different columns. But I am not sure what consequences this might lead to. So if you have experienced such situations which one would be the best way to handle it?

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• nagios3 Error: Could not read object configuration data!

  - by user1493730

  I have a brand new install of nagios3 on ubuntu 12.04. After I log in to the web interface and click any link I get the error: Error: Could not read object configuration data! Here are some things you should check in order to resolve this error: Verify configuration options using the -v command-line option to check for errors. Check the Nagios log file for messages relating to startup or status data errors. I ran it with the -v option and it reported no errors: Total Warnings: 0 Total Errors: 0 Things look okay - No serious problems were detected during the pre-flight check The nagios log and apache error log and debug log all have nothing regarding this. Does anyone know how to turn on logging that will give me some kind of useful error? Or if anyone knows how to fix this specific problem without additional logging, I guess that's okay too. Thanks!

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• Paradigms fit for UI programming

  - by Inca

  This is a more specific question (or actually two, but they are related) coming from the comments of OOP technology death where someone stated that OOP is not the right paradigm for GUI programming. Reading the comments there and here I still have the feeling there are things to learn: which programming paradigms are considered good fits and why are they better than others (perhaps with examples to illustrate?) I removed the tk-example from the title and question

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• Retrieve a user's Exchange database in powershell

  - by Paul

  Hey Everyone, I've scoured the interwebs for a few days now off and on to find this. I am creating a powershell script for email-enabling new user's(Exchange 2007). To give you a little background when we have a new hire, their AD account is created at our off-site helpdesk, but they don't create their email account. I'm trying to automate the process of mail-enabling the user which involves putting them in the same database as an existing user, disable imap pop activesync, and lastly email the requester of the ticket. I would like to just get prompted for the New User's name, User to Replicate(mailbox, storage group, database), and the person to email after it's been created. So if someone could just help with a command to Retrieve a user's Exchange database in powershell that would be great, but if people also want to help with my hacked up script please do so as well!!! Here is what I have so far: Write-output “ENTER THE FOLLOWING DETAILS” $DName = Read-Host “User Diplay Name" $RUser = Read-Host "Replicate User(Database Grab)" ***$RData = #get the Replicate user's mailbox database here*** $REmail = #either just use a Read-Host “Requester's Email address" or ask for Requester's name and pipe through their email address by digging for it w/ powershell Enable-Mailbox -Identity "$DName" -Database "$RData" Send-MailMessage -From "John Doe <[email protected]>" -To (put $REmail here which is the Requester's email) -Subject "Test Person's email account" -Body "Test Person's email account has been setup.`n`n`nJohn Doe`nGeneric Company`nSystems Administrator`nOffice: 123.456.7890`[email protected]" -SmtpServer genericexchange.exchange.com

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• overriding implemented base class methods

  - by user793468

  I read somewhere that the chain of inheritance breaks when you alter a behavior from derived class. What does "altering a behavior" mean here? Is overriding an already implemented method in base class considered as "altering behavior"? Or, does the author mean altering method signatures and the output? Also, I ready Duplicating code is not a good practice, and its a maintenance nightmare. Again, does overriding an already implemented method in base class considered "Duplicating code"? If not, what would be considered as "Duplicating code"? I

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