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• Any Good Cocos2d Pause Menu Library

  - by Mahbubur R Aaman

  Background : From http://code.google.com/p/cocos2d-iphone/issues/detail?id=173 Scenes/Nodes doesn't support the CocosNodeOpacity protocol. From http://playsnackgames.com/blog/2011/09/cocos2d-tutorial-creating-a-reusable-pause-layer/ Cocos2d offers a simple method to pause and resume itself, but these methods stop the CCDirector (the class that manages most aspects of a Cocos2d’s app lifetime) from running actions and lower the fps to 5 to conserve battery life. Related issues http://www.cocos2d-iphone.org/forum/topic/4368 http://www.cocos2d-iphone.org/forum/topic/151 http://stackoverflow.com/questions/5852354/cocos2d-engine-pause-resume http://stackoverflow.com/questions/11878450/how-to-pause-a-layer-in-cocos2d-2-0 Question : Is there any Good Cocos2d Pause Menu Library solving these tricky issues? This will save many hours of Game Developer's life.

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• Computer Science or Computer Engineering for Data Science and Machine Learning

  - by ATMathew

  I'm a 25 year old data consultant who is considering returning to school to get a second bachelors degree in computer science or engineering. My interest is data science and machine learning. I use programming as a means to an end, and use languages like Python, R, C, Java, and Hadoop to find meaning in large data sets. Would a computer science or computer engineering degree be better for this? I realize that a statistics degree may be even more beneficial, but I'll be at a school which dosn't have a stats department or a computational math department.

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• WebForms vs MVC (again)

  There's a new video up on www.asp.net which aims to help developers pick between ASP.NET WebForms and ASP.NET MVC. The video boils down to 5 benefits per technology which Microsoft thinks you should consider. Let's go over the points, shall we? First, ASP.NET WebForms: 1 - Familiar control and event base programming model The claim here is that the ASP.NET model is comfortable for WinForm programmers (thankfully this unbiased analysis left out who it's more familiar for). This is largely...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• SQL SERVER – Replace a Column Name in Multiple Stored Procedure all together

  - by pinaldave

  I receive a lot of emails every day. I try to answer each and every email and comments on Facebook and Twitter. I prefer communication on social media as this gives opportunities to others to read the questions and participate along with me. There is always some question which everyone likes to read and remember. Here is one of the questions which I received in email. I believe the same question will be there any many developers who are beginning with SQL Server. I decided to blog about it so everyone can read it and participate. “I am beginner in SQL Server. I have a very interesting situation and need your help. I am beginner to SQL Server and that is why I do not have access to the production server and I work entirely on the development server. The project I am working on is also in the infant stage as well. In product I had to create a multiple tables and every table had few columns. Later on I have written Stored Procedures using those tables. During a code review my manager has requested to change one of the column which I have used in the table. As per him the naming convention was not accurate. Now changing the columname in the table is not a big issue. I figured out that I can do it very quickly either using T-SQL script or SQL Server Management Studio. The real problem is that I have used this column in nearly 50+ stored procedure. This looks like a very mechanical task. I believe I can go and change it in nearly 50+ stored procedure but is there a better solution I can use. Someone suggested that I should just go ahead and find the text in system table and update it there. Is that safe solution? If not, what is your solution. In simple words, How to replace a column name in multiple stored procedure efficiently and quickly? Please help me here with keeping my experience and non-production server in mind.” Well, I found this question very interesting. Honestly I would have preferred if this question was asked on my social media handles (Facebook and Twitter) as I am very active there and quite often before I reach there other experts have already answered this question. Anyway I am now answering the same question on the blog so all of us can participate here and come up with an appropriate answer. Here is my answer - “My Friend, I do not advice to touch system table. Please do not go that route. It can be dangerous and not appropriate. The issue which you faced today is what I used to face in early career as well I still face it often. There are two sets of argument I have observed – there are people who see no value in the name of the object and name objects like obj1, obj2 etc. There are sets of people who carefully chose the name of the object where object name is self-explanatory and almost tells a story. I am not here to take any side in this blog post – so let me go to a quick solution for your problem. Note: Following should not be directly practiced on Production Server. It should be properly tested on development server and once it is validated they should be pushed to your production server with your existing deployment practice. The answer is here assuming you have regular stored procedures and you are working on the Development NON Production Server. Go to Server Note >> Databases >> DatabaseName >> Programmability >> Stored Procedure Now make sure that Object Explorer Details are open (if not open it by clicking F7). You will see the list of all the stored procedures there. Now you will see a list of all the stored procedures on the right side list. Select either all of them or the one which you believe are relevant to your query. Now… Right click on the stored procedures >> SELECT DROP and CREATE to >> Now select New Query Editor Window or Clipboard. Paste the complete script to a new window if you have selected Clipboard option. Now press Control+H which will bring up the Find and Replace Screen. In this screen insert the column to be replaced in the “Find What”box and new column name into “Replace With” box. Now execute the whole script. As we have selected DROP and CREATE to, it will created drop the old procedure and create the new one. Another method would do all the same procedure but instead of DROP and CREATE manually replace the CREATE word with ALTER world. There is a small advantage in doing this is that if due to any reason the error comes up which prevents the new stored procedure to be created you will have your old stored procedure in the system as it is. “ Well, this was my answer to the question which I have received. Do you see any other workaround or solution? Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Stored Procedure, SQL Tips and Tricks, T SQL, Technology

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• What functionality does dynamic typing allow?

  - by Justin984

  I've been using python for a few days now and I think I understand the difference between dynamic and static typing. What I don't understand is under what circumstances it would be preferred. It is flexible and readable, but at the expense of more runtime checks and additional required unit testing. Aside from non-functional criteria like flexibility and readability, what reasons are there to choose dynamic typing? What can I do with dynamic typing that isn't possible otherwise? What specific code example can you think of that illustrates a concrete advantage of dynamic typing?

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• Teamwork 101 for the solo newbie

  - by clankercrusher

  Forgive my newbishness but I have a question to ask about teamwork...mainly because I stink at it. Most of my projects up until this point have been solo so I have a very limited experience with teamwork. I did make graphics for a game that was being developed by several people, but that was completely different than programming with several different people. Right now I'm working with someone else on an indie MMO along with a few other team members. I've already made some pretty stupid mistakes, (like rewriting EVERYTHING) so I have two questions for you guys: 1) What are some of the most common mistakes that people make in a team environment and how can they be avoided? 2) How can the structure of your program be altered to allow for multiple teams members to work on different parts of the program at the same time? P.S. Is this the right stack exchange site for this type of question? (if not, where does it go? Thanks)

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• Prevent service from starting

  - by Evan Plaice

  So, I do Arduino development on my system to program arduinos using the FTDI USB programming interface (if you have no idea what this means don't worry). The issue arises because the FTDI interface uses tty to communicate and it conflicts with one of the default ubuntu services. The default service in question is called brltty (which enables braille accessibility for people with impaired vision). Considering that I don't have any particular use for this service and it's annoying to stop it manually (using 'service brltty stop') after I restart my system... Where would I configure this (or any) service to prevent it from loading on startup? Note: I also have this issue with qemu-kvm conflicting with virtualbox.

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• Typing commands into a terminal always returns "-bash: /usr/bin/python: is a directory"

  - by Artur Sapek

  I think I messed something up on my Ubuntu server while trying to upgrade to Python 2.7.2. Every time I type in a command that doesn't have a response, the default from bash is this: -bash: /usr/bin/python: is a directory Just like it would say if I typed the name of a directory. But this happens every time I enter a command that doesn't do anything. artur@SERVER:~$ dslkfjdsklfdshjk -bash: /usr/bin/python: is a directory I remember messing with the update-alternatives to point at python at some point, perhaps that could be it? Any inklings as to why this is happening? Related to this problem is also the fact that when I try using easy_install it tells me -bash: /usr/bin/easy_install: /usr/bin/python: bad interpeter: Permission denied /etc/fstab/ is set to exec. I've read that could fix the second problem but it hasn't.

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• Applicability of the Joel Test to web development companies

  - by dreftymac

  QUESTION: How can you re-write the questions of the Joel test to apply to web developers? 1. Do you use source control? (source control for all aspects of your app, including configuration, database and user-based settings?) 2. Can you make a build in one step? (can you deploy a site from staging to prod in 1 step?) ... 10. Do you have testers? (how do you test AJAX and CSS?) BACKGROUND: This is for people who work in a shop that does some web development but also uses some off-the-shelf tools like Drupal and Wordpress, but doing custom development on top of that. RELATED LINKS: http://www.joelonsoftware.com/articles/fog0000000043.html What do you think about the Joel Test?

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• JavaOne pictures and Community Commentary on JCP Awards

  - by heathervc

  We posted some pictures from JCP related events at JavaOne 2012 on the JCP Facebook page today.  The 2012 JCP Program Award winners and some of the nominees responded to the community recognition of their achievements during some of the JCP events last week.     “Our job on the EC is to balance the need of innovation – so we don’t standardize too early, or too late. We try to find that sweet spot that makes innovation and standardization work together, and not against each other.”- Ben Evans, CEO of jClarity and Executive Committee (EC) representative of the London Java Community, 2012 JCP Member/Participant of the Year Winner“SouJava has been evangelizing the Java platform, promoting the Java ecosystem in Brazil, and contributing to JSRs for several years. It’s very gratifying to have our work recognized, on behalf of many developers and Java User Groups around the world. This really is the work of a large group of people, represented by the few that can be here tonight.”- Michael Santos, representative of SouJava, 2012 JCP Member/Participant of the Year Winner "In the last years Credit Suisse has contributed to the development of Java EE specifications through participation in many customer advisory boards, through statements of requirements for extensions to the core Java related products in use, and active participation in JSRs. Winning the JCP Outstanding Spec Lead Award 2012 is very encouraging for our engagement and also demonstrates the level of expertise and commitment to drive the evolution of Java. Victor Grazi is happy and honored to receive this award." - Susanne Cech Previtali, Executive Committee (EC) representative of Credit Suisse, accepting award for 2012 JCP Outstanding Spec Lead Winner "Managing a JSR is difficult. There are so many decisions to be made and so many good and varied opinions, you never really know if you have decided correctly. The key to success is transparency and collaboration. I am truly humbled by receiving this award, there are so many other active JSRs.” Victor added that going forward in the JCP EC, they would like to simplify and open the process of participation – being addressed in the JCP.Next initiative of the JCP EC. "We would also like to encourage the engagement of universities, professors and students – as an important part of the Java community. While innovation is the lifeblood of our community and industry, without strong standards and compatibility requirements, we all end up in a maze of technology where everything is slightly different and doesn’t quite work with everything else." Victo Grazi, Executive Committee (EC) representative of Credit Suisse, 2012 JCP Outstanding Spec Lead Winner“I am very pleased, of course, to accept this award, but the credit really should go to all of those who have participated in the work of the JCP, while pushing for changes in the way it operates.  JCP.Next represents three JSRs. The first two are done, but the final step, JSR 358, is the complicated one, and it will bring in the lawyers. Just to give you an idea of what we’re dealing with, it affects licensing, intellectual property, patents, implementations not based on the Reference Implementation (RI), the role of the RI, compatibility policy, possible changes to the Technical Compatibility Kit (TCK), transparency, where do individuals fit in, open source, and more.”- Patrick Curran, JCP Chair, Spec Lead on JCP.Next JSRs (JSR 348, JSR 355 and JSR 358), 2012 JCP Most Significant JSR Winner“I’m especially glad to see the JCP community recognize JCP.Next for its importance. The governance work it represents is KEY to moving the Java platform forward and the success of the technology.”- John Rizzo, Executive Committee (EC) representative of Aplix Corporation, JSR Expert Group Member “I am deeply honored to be nominated. I had the privilege to receive two awards on behalf of Expert Groups and Spec Leads two years ago. But this time, I am nominated personally, which values my own contribution to the JCP, and of course, participation in JSRs and the EC work. I’m a fan of Agile Principles and Values Working. Being an Agile Coach and Consultant, I use it for some of the biggest EC Member companies and projects. It fuels my ability to help the JCP become more agile, lean and transparent as part of the JCP.Next effort.” - Werner Keil, Individual Executive Committee (EC) Member, a 2012 JCP Member/Participant of the Year Nominee, JSR Expert Group Member“The JCP ever has been some kind of institution for me,” Markus said. “If in technical doubt, I go there, look for the specifications of the implementation I work with at the moment and verify what I had observed. Since the beginning of my Java journey more than 12 years back now, I always had a strong relationship with the JCP. Shaping the future of a technology by joining the JCP – giving feedback and contributing to the road ahead through individual JSRs – that brings you to a whole new level.”Calling himself, “the new kid on the block,” he explained that for years he was afraid to join the JCP and contribute. But in reality, “Every single one of the big names I meet from the different Expert Groups is a nice person. People you can actually work with,” he says. “And nobody blames you for things you don't know. As long as you are committed and bring what is worth the most: passion, experiences and the desire to make a difference.” - Markus Eisele, a 2012 JCP Member of the Year Nominee, JSR Expert Group MemberCongratulations again to all of the nominees and winners of the JCP Program Awards.  Next year, we will add another award for the group of JUG members (not an entire JUG) that makes the best contribution to the Adopt-a-JSR program.  Let us know if you have other suggestions or improvements.

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• 301 redirect to 404 page or set status code to 404 and stay on page?

  - by WPRookie82

  I have a number of pages on my website that only administrators can access and access to these pages is given if a querystring value if found and correctly set. For example: http://www.mydomain.com/show-daily-statistics?key=abc The above link will show the content of the page but anything else such as the below will not: http://www.mydomain.com/show-daily-statistics Now I was thinking about what to do if search engines and/or non-admin users somehow land on these hidden pages. I can of course either change the status code of the page to 404 or else 301 redirect to: http://www.mydomain.com/404-error What's the best solution in respect to Google and SEO?

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• Do Not Optimize Without Measuring

  - by Alois Kraus

  Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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• CUDA 4.0 : sortie de la Release Candidate de l'architecture de calcul parallèle de NVIDIA

  CUDA 4.0 : sortie de la Release Candidate De l'architecture de calcul parallèle de NVIDIA La sortie cette semaine aux développeurs enregistrés de CUDA est l'accomplissement de milliers d'heures dédiées à ce projet. Cette technologie peut sembler jeune, sa première version, la 1.0, n'a été sortie qu'en 2007. L'effet de cette sortie sur le monde entier n'a, sans nul doute possible, pas été nul. Elle n'est pas non plus le seul terrain d'avance pour les technologies massivement parallèles sur matériel NVIDIA : les API comme OpenCL et DirectCompute sont elles aussi supportées et améliorées, en plus d'un accès direct au GPU en C, C++ et Fortran. Comme toujours, NVIDIA est à la recherch...

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• how should I network my turn based game?

  - by ddriver1

  I'm writing a very basic turn based strategy game which allows a player to select units and attack enemy units on their turn. The game is written in Java using the slick2d library and I plan to use kyronet for the networking api. I want the game to be networked, but I do not know how I should go about it. My current idea is to connect two users together, and the first one to join the game becomes the game host, while the other becomes the client. However after reading http://gafferongames.com/networking-for-game-programmers/what-every-programmer-needs-to-know-about-game-networking/ it seems my game would be suited to a peer to peer lockstep model. Would that make programming the networking side much easier? Any suggestions on how I should structure my networking would be greatly appreciated

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• How do I report a missing package dependency during an upgrade?

  - by crasic

  A friend of mine (somewhat new to linux) recently upgraded from 10.10 to 11.04 and his OS broke from the upgrade. A few minutes of troubleshooting showed that the culprit was the PAE kernel that the upgrade decided to install since it determined he had 4GB of phyisical RAM. More specifically the upgrade forgot to install the linux-headers-generic-pae required by the closed source nvidia drivers. I'm not entirely sure how to report this bug to the devs. Its an easy fix (after booting into the non-pae kernel and installing the package everything worked), but they are encouraging users to use the built-in bug reporting system and I'm not entirely certain how to report update bugs.

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• Why are there so many spaces and line breaks in Unicode?

  - by maaartinus

  Unicode has maybe 50 spaces \u0009\u000A-\u000D\u0020\u0085\u00A0\u1680\u180E\u2000-\u200A\u2028\u2029\u202F\u205F\u3000][\u0009\u000A-\u000D\u0020\u0085\u00A0\u1680\u180E\u2000-\u200A\u2028\u2029\u202F\u205F\u3000 and 6 line breaks not only CRLF, LF, CR, but also NEL (U+0085), PS (U+2029) and LS (U+2028). Maybe I could understand most of the spaces and PS ("Paragraph separator"), but what are "Next Line" and "Line separator" good for? It all looks like invented by a very big committee where everybody wanted their own space and the leaders were granted one line break each. But seriously, how do you deal with it when your programming language doesn't support it (or does it wrong as e.g. Java does)?

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• How to setup Thinkpad features on Thinkpad T500

  - by gijoemike

  I have a IBM-Lenovo Thinkpad T500. I was previously a exclusive windows user, but recently installed ubuntu and loving it because of speed and interface. The only thing is that I don't get some features that I came to enjoy in windows. I need help setting these up: Hard-drive protection - active protection software that pauses drive when there is movement My printer doesn't work (can't find the driver for this one): canon Ip2600 A way to change which graphics chip to use while in OS. I have both the integrated and non integrated (dual-graphics). (If not easy to setup, I know there's a way to do it before it boots, but don't know how). CPU performance level - in windows you can pick "high performance", "power saver", etc.. to save batteries. My integrated camera w/light - it works but need an app where I can record videos, take snapshots, etc. can't find one that works. Thanks!

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• Liskov Substitution Principle and the Oft Forgot Third Wheel

  - by Stacy Vicknair

  Liskov Substitution Principle (LSP) is a principle of object oriented programming that many might be familiar with from the SOLID principles mnemonic from Uncle Bob Martin. The principle highlights the relationship between a type and its subtypes, and, according to Wikipedia, is defined by Barbara Liskov and Jeanette Wing as the following principle:   Let be a property provable about objects of type . Then should be provable for objects of type where is a subtype of .   Rectangles gonna rectangulate The iconic example of this principle is illustrated with the relationship between a rectangle and a square. Let’s say we have a class named Rectangle that had a property to set width and a property to set its height. 1: Public Class Rectangle 2: Overridable Property Width As Integer 3: Overridable Property Height As Integer 4: End Class   We all at some point here that inheritance mocks an “IS A” relationship, and by gosh we all know square IS A rectangle. So let’s make a square class that inherits from rectangle. However, squares do maintain the same length on every side, so let’s override and add that behavior. 1: Public Class Square 2: Inherits Rectangle 3:  4: Private _sideLength As Integer 5:  6: Public Overrides Property Width As Integer 7: Get 8: Return _sideLength 9: End Get 10: Set(value As Integer) 11: _sideLength = value 12: End Set 13: End Property 14:  15: Public Overrides Property Height As Integer 16: Get 17: Return _sideLength 18: End Get 19: Set(value As Integer) 20: _sideLength = value 21: End Set 22: End Property 23: End Class   Now, say we had the following test: 1: Public Sub SetHeight_DoesNotAffectWidth(rectangle As Rectangle) 2: 'arrange 3: Dim expectedWidth = 4 4: rectangle.Width = 4 5:  6: 'act 7: rectangle.Height = 7 8:  9: 'assert 10: Assert.AreEqual(expectedWidth, rectangle.Width) 11: End Sub   If we pass in a rectangle, this test passes just fine. What if we pass in a square?   This is where we see the violation of Liskov’s Principle! A square might "IS A” to a rectangle, but we have differing expectations on how a rectangle should function than how a square should! Great expectations Here’s where we pat ourselves on the back and take a victory lap around the office and tell everyone about how we understand LSP like a boss. And all is good… until we start trying to apply it to our work. If I can’t even change functionality on a simple setter without breaking the expectations on a parent class, what can I do with subtyping? Did Liskov just tell me to never touch subtyping again? The short answer: NO, SHE DIDN’T. When I first learned LSP, and from those I’ve talked with as well, I overlooked a very important but not appropriately stressed quality of the principle: our expectations. Our inclination is to want a logical catch-all, where we can easily apply this principle and wipe our hands, drop the mic and exit stage left. That’s not the case because in every different programming scenario, our expectations of the parent class or type will be different. We have to set reasonable expectations on the behaviors that we expect out of the parent, then make sure that those expectations are met by the child. Any expectations not explicitly expected of the parent aren’t expected of the child either, and don’t register as a violation of LSP that prevents implementation. You can see the flexibility mentioned in the Wikipedia article itself: A typical example that violates LSP is a Square class that derives from a Rectangle class, assuming getter and setter methods exist for both width and height. The Square class always assumes that the width is equal with the height. If a Square object is used in a context where a Rectangle is expected, unexpected behavior may occur because the dimensions of a Square cannot (or rather should not) be modified independently. This problem cannot be easily fixed: if we can modify the setter methods in the Square class so that they preserve the Square invariant (i.e., keep the dimensions equal), then these methods will weaken (violate) the postconditions for the Rectangle setters, which state that dimensions can be modified independently. Violations of LSP, like this one, may or may not be a problem in practice, depending on the postconditions or invariants that are actually expected by the code that uses classes violating LSP. Mutability is a key issue here. If Square and Rectangle had only getter methods (i.e., they were immutable objects), then no violation of LSP could occur. What this means is that the above situation with a rectangle and a square can be acceptable if we do not have the expectation for width to leave height unaffected, or vice-versa, in our application. Conclusion – the oft forgot third wheel Liskov Substitution Principle is meant to act as a guidance and warn us against unexpected behaviors. Objects can be stateful and as a result we can end up with unexpected situations if we don’t code carefully. Specifically when subclassing, make sure that the subclass meets the expectations held to its parent. Don’t let LSP think you cannot deviate from the behaviors of the parent, but understand that LSP is meant to highlight the importance of not only the parent and the child class, but also of the expectations WE set for the parent class and the necessity of meeting those expectations in order to help prevent sticky situations.   Code examples, in both VB and C# Technorati Tags: LSV,Liskov Substitution Principle,Uncle Bob,Robert Martin,Barbara Liskov,Liskov

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• Rendering CV template with XeLaTex

  - by jacob

  Installed kubuntu on thursday Installed LaTeX on my kubuntu machine, using full Compiled an old document and it worked fine Downloaded a CV template from http://www.latextemplates.com/template/two-column-one-page-cv Compiled it, got error Fatal fontspec error: "cannot-use-pdftex" The fontspec package requires either XeTeX or LuaTeX to function. You must change your typesetting engine to, e.g., "xelatex" or "lualatex" instead of plain "latex" or "pdflatex". See the fontspec documentation for further information. For immediate help type H . Installed XeLaTex using this guide http://ledgersmb.org/faq/xelatex i.e. 7 Installed texlive-xetex that includes xelatex apt-get install texlive-xetex apt-get install liblatex-{driver,encode,table}-perl apt-get install libtemplate-plugin-latex-per 8) Compiled CV template again, did not work. Related: No Xelatex in texlive 2012 Excuse me if my question is not clear enough, I'm new to linux.

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• Firefox 4 : les extensions se mettront à jour automatiquement, mais pas le navigateur

  Firefox 4 : les extensions se mettront à jour automatiquement Mais pas le navigateur Mise à jour du 07/12/10 A mesure que le navigateur de la Fondation Mozilla enchaîne les betas (7 à ce jour - lire ci-avant), la version définitive de Firefox 4 se précise. Dernière nouveauté en date, dévoilée par Jenny Boriss, en charge de l'UI et de l'expérience utilisateur, la mise à jour automatique ? et silencieuse ? des extensions. Jusqu'ici, Mozilla avait fait le choix d'indiquer à l'utilisateur qu'une mise à jour était disponible pour tel ou tel add-on. Ce dernier pouvait alors choisir de l'appliquer ou non. Mieux, la beta 7 perm...

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• Happy 3rd Birthday SilverlightCream!

  - by Dave Campbell

  Happy 3rd Birthday!     Yesterday (May 16) was the 'Birthday' of SilverlightCream, which started just after MIX in 2007 with a post "Interesting Silverlight posts today: Silverlight Control & Silverlight Pad". Too many good posts flying around led me to want to archive them, particularly since I was being aggregated at a new site Silverlight.net, and I could give some of that 'reach' to the community. Saturday's post was number 862, and as of that post, there were 5697 blog posts archived in the database all tagged up and searchable at SilverlightCream.com using the search page. The search needs to be better, and that's another discussion, but it does work. The blog didn't begin life as the SilverlightCream blog, as is obvious from the name, but once I realized people were following it closely, I've tried to keep the signal-to-noise ratio very high. I even secured another blog for when I just want to rant about something to keep that stuff out of this one :) If you've been around since MIX07 days you've heard all this, but after talking to some people at MIX10 I realized not everyone knows all the ways the information is presented, so I figured doing a post like this once a year probably isn't a bad idea :) I scrounge through an ever-growing list of blogs (right now sitting at 505) looking for good stuff. I try to spin through the list every day, but with the list growing that large, it's getting tough. I usually use it as a background task while working or watching TV. If I just sit and go through the blogs it takes about an hour. The list is long enough now that from time to time, I'll only get partway through it and have 10 to 13 entries, so I'll just stop there and go on the next day... I don't like to have more than 15 in any single post. It's all pattern recognition as in "seen that", "seen that", "that's new", etc... so if you're a blogger, look at a heading below for some comments about blogging from my perspective. When I see something new, I make sure you're not pulling a 'Mike Taulty' on me and dumping 6 or 8 new posts in one day :), and I tag the ones I want to review. If there's not a lot going on, I may just push the posts as I come across them. Some days there may be 60 posts in that 'to review' list! Some are non-Silverlight, some are essentially duplicates of others, some are demos, ads, new releases of something, session materials, etc. I push lots of material into a database at WynApse.com, and the "Tagged Posts" menu on the left sidebar there takes you to a tag cloud of (at this very moment) "9224 articles tagged 13915 different ways using 459 unique tags". There are links in there on Gibson guitars, Jazz Guitar instructional stuff, Ford F-250 links, and tons of technical and non-technical stuff I've been aggregating for about 5 years now. So when I decide to blog (or shoutout) something, I first push it into the database at WynApse.com. Then I tag it all up and push it into the database at SilverlightCream.com. Then it gets pushed to @SilverlightNews. For a little over a year now, we're tracking unique IP hits on posts launched from either the blog post or from one of the SilverlightCream.com pages, and the posts with top hits from unique IP addresses in the last 7 days are displayed in a 'Skim' page at SilverlightCream... and that page needs work as well. The Skim page and tracking was the brainchild of my buddy Michael Washington. What I blog/shoutout After some time doing posts, I decided there were things that probably have no need to be searchable, but are good information, so I post those as 'Shoutouts'. Eventually I also decided the Shoutouts should get posted to @SilverlightNews, and that's now taking place. Notes to bloggers Remember I said spinning throught the Big List-o-BlogsTM is pattern recognition... that means I don't spend a lot of time on any individual blog deciding if it has new content. If you're familiar with the term 'Above the Fold', then you're probably ok. If I have to scroll the page to see if there's something new, or wade through some maze of menus, I'm probably going to miss new stuff. Likewise if you only show the latest on the front page and make it a puzzle to find the rest of them, or if you make the titles and initial graphics almost identical to the previous article, I'll miss it. Another thing is name/brand-recognition. Far be it for me (WynApse) to comment on someone blogging with a pseudonym, but if you want to get get some recognition, you are going to want your name to be available somewhere. I can think right off the top of my head of a couple good blogs that I have no idea of the individuals' real names. I can pull that off a bit because I've been around so long almost everyone knows who I am, but if you're new to the blog-o-sphere, being able to be name-recognized is as important as getting your brand out there. Kick my tires Finally, stuff happens... I may hit the wrong key and delete your blog, or a post might slip past me and I not realize it's new because of the naming, and never blog it. If you think I missed something, send me an email or use the submit page at SilverlightCream.com. Some bloggers have figured out that if they submit (one way or another) to me, their posts will go out next. I try to honor anyone that takes the time to submit with a quicker 'Cream posting. Thanks! Finally, thanks to everyone that contributes to the community as a whole... the blogs, the videos, and the presentations. A special thanks to everyone that reads SilverlightCream, or follows @WynApse or @SilverlightNews. Keep it all coming, and... Stay in the 'Light

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• Will JVisualVM degrade application performance?

  - by rocky

  I have doubts in JVisual VM profiler tool related to performance. I have requirement to implement a JVM Monitoring tool for my enterpise java application. I have gone through some profiling tools in market but all them are having some kind of agent file which we need include in server startup. I have a fear that these client agent will degrade my application performance will more. So I have decided to JVisual VM because this profiler tool comes with JDK itself but before implementing JVisualVM, does anybody faces any issues with JVisualVM profiler tool? As well as, is this safe if I implement in application?

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• How to change System default language on GNOME3?

  - by Vor

  I just installed GNOME3 on my Ubuntu. Everything worked fine till I restarted computer. Then I received a message if I want to change folders name to some other (different language, don't know what is this, but looks like Chinese). I pressed, 'keep old names' but it still changed all my folder names! And also the rest of the names. (like settings, and all that staff). So if you can give me the direction on where to click (cause all English names changed to non-English) and I simply don't know what does any of them means!

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• File added to project doesn't get added to packages

  - by lorin

  I'm creating customized binary versions of OpenStack nova packages (lp:nova) using their packaging scripts (lp:~openstack-ubuntu-packagers/ubuntu/natty/nova/ubuntu). I create binaries by doing: dpkg-buildpackage -b -rfakeroot -tc -uc -D This creates a set of packages (python-nova, nova-common, nova-compute, ...). In our customized version of the code (lp:~usc-isi/nova/hpc-trunk), we recently merged in some changes from another branch, and there's now a new file in our repository that wasn't in upstream: nova/virt/cpuinfo.xml.template. This file isn't getting added to any of the packages, where it should be added to python-nova. Why wouldn't dpkg-buildpackage be including this file? A more basic question: how does dpkg-buildpackage determine which files go in which packages? Is it related at all to the debian/watch file? This contains some URLs that are pointing to the upstream project. version=3 http://launchpad.net/nova/+download http://launchpad.net/nova/.*/nova-(.*)\.tar\.gz http://nova.openstack.org/tarballs/ nova-(.*).tar.gz

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• What are the benefits and drawback of documentation vs tutorials vs video tutorials [closed]

  - by Cat

  Which types of learning resources do you find the most helpful, for which kinds of learning and/or perhaps at specific times? Some examples of types of learning you could consider: When starting to integrate a new SDK inside an existing codebase When learning a new framework without having to integrate legacy code When digging deeper into an already-used SDK that you may not know very well yet For example - (video) tutorials are usually very easy to follow and tells a story from beginning to end to get results, but will nearly always assume starting from scratch or a previous tutorial. Therefore such a resource is useful for quick learning if you don't have legacy code around, but less so if you have to search for the best-fit to the code you already have. SDK Documentation on the other hand is well-structured but does not tell a story. It is more difficult to get to a specific larger result with documentation alone, but it is a better fit when you do have legacy code around and are searching for perhaps non-obvious ways of employing the SDK or library. Are there other forms of resources that you find useful, such as interactive training?

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