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• Java Spotlight Episode 98: Cliff Click on Benchmarkings

  - by Roger Brinkley

  Interview with Cliff Click of 0xdata on benchmarking. Recorded live at JFokus 2012. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News Bean Validation 1.1 Java EE 7 Roadmap Java JRE Update 7u7 and 6u35 available. Change to Java SE 7 and Java SE 6 Update Release Numbers JCP 2012 Award Nominations Announced Griffon JavaFX Plugin Events Sep 3-6, Herbstcampus, Nuremberg, Germany Sep 10-15, IMTS 2012 Conference,  Chicago Sep 12,  The Coming M2M Revolution: Critical Issues for End-to-End Software and Systems Development,  Webinar Sep 30-Oct 4, JavaONE, San Francisco Oct 3-4, Java Embedded @ JavaONE, San Francisco Oct 15-17, JAX London Oct 30-Nov 1, Arm TechCon, Santa Clara Oct 22-23, Freescale Technology Forum - Japan, Tokyo Nov 2-3, JMagreb, Morocco Nov 13-17, Devoxx, Belgium Feature Interview Cliff Click is the CTO and Co-Founder of 0xdata, a firm dedicated to creating a new way to think about web-scale data storage and real-time analytics. I wrote my first compiler when I was 15 (Pascal to TRS Z-80!), although my most famous compiler is the HotSpot Server Compiler (the Sea of Nodes IR). I helped Azul Systems build an 864 core pure-Java mainframe that keeps GC pauses on 500Gb heaps to under 10ms, and worked on all aspects of that JVM. Before that I worked on HotSpot at Sun Microsystems, and am at least partially responsible for bringing Java into the mainstream. I am invited to speak regularly at industry and academic conferences and has published many papers about HotSpot technology. I hold a PhD in Computer Science from Rice University and about 15 patents. What’s Cool Shaun Smith’s Devoxx 2011 talk "JPA Multi-Tenancy & Extensibility" now freely available at Parleys.

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• Can you point me to a nontrivial strategy pattern implementation?

  - by Eugen Martynov

  We are faced implementing a registration workflow with many branches. There are three main flows which in some conditions lead to one another. Each flow has at least four different steps; some steps interact with the server, and every step adds more information to the state. Also the requirement is to have it persistent between sessions, so if the user closes the app (this is a mobile app), it will restore the process from the last completed step with the state from the previous session. I think this could benefit from the use of the strategy pattern, but I've never had to implement it for such a complex case. Does anyone know of any examples in open source or articles from which I could find inspiration? Preferably the examples would be from a live/working/stable application. I'm interested in Java implementation mostly; we are developing for Java mobile phones: android, blackberry and J2ME. We have an SDK which is quite well separated from platform specific implementations, but examples in C++, C#, Objective-C or Python would be acceptable.

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• Current trends in Random Access Memory

  - by Nutel

  As I know for now because of laws of Physics there will be not any tangible improvements in CPU cycles per second for the nearest future. However because of Von Neumann bottleneck it seems to not be an issue for non-server applications. So what about RAM, is there any upcoming technologies that promise to improve memory speed or we are stack with the current situation till quantum computers will come out from labs?

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• How to become a "faster" programmer?

  - by Nick Gotch

  My last job evaluation included just one weak point: timeliness. I'm already aware of some things I can do to improve this but what I'm looking for are some more. Does anyone have tips or advice on what they do to increase the speed of their output without sacrificing its quality? How do you estimate timelines and stick to them? What do you do to get more done in shorter time periods? Any feedback is greatly appreciated, thanks,

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• Cat 6 Only 100mbit speed

  - by Stu2000

  I tried two different cat6 cables directly connected between my two ubuntu machines. This one I ordered online: http://www.amazon.co.uk/gp/product/B002SQPDXS/ref=wms_ohs_product only achieves 100mbit speeds, but does appear to be supporting cross-talk (direct pc to pc), the other cat 6 cable, worked perfectly and gets the full 1gigabit speed. Both tests were performed using ftp and checking the network monitor with direct pc to pc connection. Did the product from amazon lie to me or do I need to manually set a setting somewhere in ubuntu for some cables? I had thought 10 quid for 20m of gigabit ethernet cable was a bit cheap, you get what you pay for... Regards, Stu Update: It seems that after rebooting, the device is set to 1000mbit sec when looking it up with sudo ethtool eth0 However after a while, this will drop down to just 100, after which to reset it to 1000 again, I have to reboot, and simply unpugging and re-plugging in the cable doesn't do it. I tried setting this in networking config file as suggested here: auto eth0 iface eth0 inet static pre-up /usr/sbin/ethtool -s eth0 speed 1000 duplex full but that resulted in my networking failing to start. Is there a problem with my 'auto-negotiation' or something? Can I manually override a setting to 1000mbit?

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• Make methods that do not depend on instance fields, static?

  - by m3th0dman

  Recently I started programming in Groovy for a integration testing framework, for a Java project. I use Intellij IDEA with Groovy plug-in and I am surprised to see as a warning for all the methods that are non-static and do not depend on any instance fields. In Java, however, this is not an issue (at least from IDE's point of view). Should all methods that do not depend onto any instance fields be transformed into static functions? If true, is this specific to Groovy or it is available for OOP in general? And why?

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• Is ORM an Anti-Pattern?

  - by derphil

  I had a very stimulating and interessting discussion with a colleague about ORM and it's Pros and Cons. In my opinion, an ORM is useful only in the rarest cases. At least in my experience. But I don't want to list my own arguments at this time. So I ask you, what do you think about ORM? What are the Pros and the Cons? P.S. I've posted this "question" yesterday on Stackoverflow, but some of the user think, that this should better posted here.

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• A programming language that does not allow IO. Haskell is not a pure language

  - by TheIronKnuckle

  (I asked this on Stack Overflow and it got closed as off-topic, I was a bit confused until I read the FAQ, which discouraged subjective theoratical debate style questions. The FAQ here doesn't seem to have a problem with it and it sounds like this is a more appropriate place to post. If this gets closed again, forgive me, I'm not trying to troll) Are there any 100% pure languages (as I describe in the Stack Overflow post) out there already and if so, could they feasibly be used to actually do stuff? i.e. do they have an implementation? I'm not looking for raw maths on paper/Pure lambda calculus. However Pure lambda calculus with a compiler or a runtime system attached is something I'd be interested in hearing about.

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• Is loose coupling w/o use cases an anti-pattern?

  - by dsimcha

  Loose coupling is, to some developers, the holy grail of well-engineered software. It's certainly a good thing when it makes code more flexible in the face of changes that are likely to occur in the foreseeable future, or avoids code duplication. On the other hand, efforts to loosely couple components increase the amount of indirection in a program, thus increasing its complexity, often making it more difficult to understand and often making it less efficient. Do you consider a focus on loose coupling without any use cases for the loose coupling (such as avoiding code duplication or planning for changes that are likely to occur in the foreseeable future) to be an anti-pattern? Can loose coupling fall under the umbrella of YAGNI?

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• Break the object body

  - by Siddharth

  In my game, I want to break the object body creating slicing effect. After research I found that I have to use ray casting but I don't know how to use it. If some one know how to break the physics body then please provide information to me. EDIT : I don't have any logic how to do that in andengine. Only I have some link to do slicing http://www.emanueleferonato.com/2012/03/05/breaking-objects-with-box2d-the-realistic-way/ Yes I have to slice physics body into two parts. My physics body have 2d objects.

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• When to decide to introduce interfaces (pure abstract base classes) in C++?

  - by Honza Brabec

  Assume that you are developing a functionality and are 90% sure that the implementation class will stay alone. If I was in this position in Java I would probably not use the interface right now to keep the things simple. In Java it is easy to refactor the code and extract the interface later. In C++ the refactoring is not always so easy. It may require replacing values with smart pointers (because of the introduction of polymorphism) and other non-trivial tasks. On the other hand I don't much like the idea of introducing virtual calls when I am 90% sure they won't be needed. After all speed is one of the reasons to prefer C++ over simpler languages.

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• Spatial data from shapefiles (for T-SQL Tuesday #006)

  - by Rob Farley

  I’m giving a presentation on May 12th at the Adelaide .Net User Group, around the topic of spatial data, and in particular, the visualization of said data. Given that it’s about one the larger types, this post should also count towards Michael Coles’ T-SQL Tuesday on BLOB data . I wrote recently about my experience with exploded data , but what I didn’t go on to talk about was how using a shapefile like this would translate into a scenario with a much larger number of shapes, such as all the postcode...(read more)

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• Rails: Law of Demeter Confusion

  - by user2158382

  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. EDIT I completely understand and agree that this is still a violation and I need to create a method in Wallet called withdraw that handles the payment for me and that I should call that method inside the Customer class. What I don't get is that according to this process, my first example still violates the Law of Demeter because Invoice is still reaching directly into Customer to get the street. 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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• Add-ons for Firefox - Java Plugin has been blocked JRE versions below 1.6.0_31 or between 1.7.0 and 1.7.0_2

  - by user702295

  As Java 1.6u31 is not certified for use with EBS or Demantra, you may notice issues in relation to the Java plug-in.  Demantra Development is currently working to certify Java 1.6u31.  They are recommending that you upgrade to that version. EBS customers, should not be installing 1.6u31 as it is not certified.  If you do upgrade your browser, you will either need to downgrade to a lower release of Firefox or find a way of allowing Firefox to use the older version of the Java Plug-in.

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• OpenGL profiling with AMD PerfStudio 2

  - by Aurus

  I'm rendering just a really small amount of polygons for my UI but however I still tried to increase the FPS. In the end I removed redundant calls which increased the FPS. I really don't want to lose FPS for nothing so I keep looking for more improvements. The first thing I noticed is the "huge" time where no calls are made before SwapBuffer (the black one). Well I know that OpenGL works asynchronous so SwapBuffer has to wait until everything is done. But shouldn't PerfStudio mark this time also as black ? Correct me If I am wrong. The second thing I noticed is that some glUniform2f calls just take longer (the brown ones). I mean they should all upload 2floats to the GPU how can the time be so different from call to call. The program isn't even changed or something like that. I also tried to look at other programs like gDebugger or CodeXL but they often crashed and they show less statistics (only # of calls or redundant calls etc.) EDIT: I also realized that the draw calls also have different durations, which was obvious for me but sometimes drawing more vertices is faster than drawing less vertices.

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• Database Maintenance Scripting Done Right

  - by KKline

  I first wrote about useful database maintenance scripts on my SQLBlog account way back in 2008. Hmmm - now that I think about it, I first wrote about my own useful database maintenance scripts in a journal called SQL Server Professional back in the mid-1990's on SQL Server v6.5 or some such. But I digress... Anyway, I pointed out a couple useful sites where you could get some good scripts that would take care of preventative maintenance on your SQL Server, such as index defragmentation, updating...(read more)

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• Learning PHP OOP

  - by Ryan Murphy

  I have been coding PHP for about 2 years now and I THINK that I have a very good grasps of the fundamental parts of PHP, i.e. Functions foreach/IF statements sessions/cookies POST/GET Amongst a few others. I want to move on to learning OOP PHP now, so learning how to use classes and making it a really valuable skill. I have 1 requirement, the source must be a respected source that doesn't teach developers bad habits. I have the book: PHP and MySQL Web Development However, as useful as that is I would like an online source. I would like to know from people with experience in OOP PHP, how and where did they learn OOP PHP. Obviously by doing, but I would really appreciate some great resources which help me along the way.

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• Accelerating 2d object collision with other objects [on hold]

  - by Silent Cave

  Making my very first attempt at game programming with SDL/OpenGL. So I made an object Actor witch can move in all four sides with acceleration. And there are bunch of other rectangles to collide to. the image Movement and collision detection alghorythms work just fine by itself, but when combined to prevent the green rectangle from crossing black rectangles, it gives me a kind of funny resault. Let me show you the code first: from Actor.h class Actor{ public: SDL_Rect * dim; alphaColor * col; float speed; float xlGrav, xrGrav, yuGrav, ydGrav; float acceleration; bool left,right,up,down; Actor(SDL_Rect * dim,alphaColor * col, float speed, float acceleration); bool colides(const SDL_Rect & rect); bool check_for_collisions(const std::vector<SDL_Rect*> & gameObjects ); }; from actor.cpp bool Actor::colides(const SDL_Rect & rect){ if (dim->x + dim->w < rect.x) return false; if (dim->x > rect.x + rect.w) return false; if (dim->y + dim->h < rect.y) return false; if (dim->y > rect.y + rect.h) return false; return true; } movement logic from main.cpp if (actor->left){ if(actor->xlGrav < actor->speed){ actor->xlGrav += actor->speed*actor->acceleration; }else actor->xlGrav = actor->speed; actor->dim->x -= actor->xlGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x += actor->xlGrav; actor->xlGrav = 0; } } if (!actor->left){ if(actor->xlGrav - actor->speed*actor->acceleration > 0){ actor->xlGrav -= actor->speed*actor->acceleration; }else actor->xlGrav = 0; actor->dim->x -= actor->xlGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x += actor->xlGrav; actor->xlGrav = 0; } } if (actor->right){ if(actor->xrGrav < actor->speed){ actor->xrGrav += actor->speed*actor->acceleration; }else actor->xrGrav = actor->speed; actor->dim->x += actor->xrGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x -= actor->xrGrav; actor->xrGrav = 0; } } if (!actor->right){ if(actor->xrGrav - actor->speed*actor->acceleration > 0){ actor->xrGrav -= actor->speed*actor->acceleration; }else actor->xrGrav = 0; actor->dim->x += actor->xrGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->x -= actor->xrGrav; actor->xrGrav = 0; } } if (actor->up){ if(actor->yuGrav < actor->speed){ actor->yuGrav += actor->speed*actor->acceleration; }else actor->yuGrav = actor->speed; actor->dim->y -= actor->yuGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y += actor->yuGrav; actor->yuGrav = 0; } } if (!actor->up){ if(actor->yuGrav - actor->speed*actor->acceleration > 0){ actor->yuGrav -= actor->speed*actor->acceleration; }else actor->yuGrav = 0; actor->dim->y -= actor->yuGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y += actor->yuGrav; actor->yuGrav = 0; } } if (actor->down){ if(actor->ydGrav < actor->speed){ actor->ydGrav += actor->speed*actor->acceleration; }else actor->ydGrav = actor->speed; actor->dim->y += actor->ydGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y -= actor->ydGrav; actor->ydGrav = 0; } } if (!actor->down){ if(actor->ydGrav - actor->speed*actor->acceleration > 0){ actor->ydGrav -= actor->speed*actor->acceleration; }else actor->ydGrav = 0; actor->dim->y += actor->ydGrav; if(actor->check_for_collisions(gameObjects)){ actor->dim->y -= actor->ydGrav; actor->ydGrav = 0; } } So, if the green box approaches an obstacle from up or left, everything goes as planned - object stops, and it's acceleration drops to zero. But if it comes from bottom or right, it enters into obstacles inner space and starts strangely dance, I'd rather say move in inverted controls. What do I fail to see?

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• Good DBAs Do Baselines

  - by Louis Davidson

  One morning, you wake up and feel funny. You can’t quite put your finger on it, but something isn’t quite right. What now? Unless you happen to be a hypochondriac, you likely drag yourself out of bed, get on with the day and gather more “evidence”. You check your symptoms over the next few days; do you feel the same, better, worse? If better, then great, it was some temporal issue, perhaps caused by an allergic reaction to some suspiciously spicy chicken. If the same or worse then you go to the doctor for some health advice, but armed with some data to share, and having ruled out certain possible causes that are fixed with a bit of rest and perhaps an antacid. Whether you realize it or not, in comparing how you feel one day to the next, you have taken baseline measurements. In much the same way, a DBA uses baselines to gauge the gauge health of their database servers. Of course, while SQL Server is very willing to share data regarding its health and activities, it has almost no idea of the difference between good and bad. Over time, experienced DBAs develop “mental” baselines with which they can gauge the health of their servers almost as easily as their own body. They accumulate knowledge of the daily, natural state of each part of their database system, and so know instinctively when one of their databases “feels funny”. Equally, they know when an “issue” is just a passing tremor. They see their SQL Server with all of its four CPU cores running close 100% and don’t panic anymore. Why? It’s 5PM and every day the same thing occurs when the end-of-day reports, which are very CPU intensive, are running. Equally, they know when they need to respond in earnest when it is the first time they have heard about an issue, even if it has been happening every day. Nevertheless, no DBA can retain mental baselines for every characteristic of their systems, so we need to collect physical baselines too. In my experience, surprisingly few DBAs do this very well. Part of the problem is that SQL Server provides a lot of instrumentation. If you look, you will find an almost overwhelming amount of data regarding user activity on your SQL Server instances, and use and abuse of the available CPU, I/O and memory. It seems like a huge task even to work out which data you need to collect, let alone start collecting it on a regular basis, managing its storage over time, and performing detailed comparative analysis. However, without baselines, though, it is very difficult to pinpoint what ails a server, just by looking at a single snapshot of the data, or to spot retrospectively what caused the problem by examining aggregated data for the server, collected over many months. It isn’t as hard as you think to get started. You’ve probably already established some troubleshooting queries of the type SELECT Value FROM SomeSystemTableOrView. Capturing a set of baseline values for such a query can be as easy as changing it as follows: INSERT into BaseLine.SomeSystemTable (value, captureTime) SELECT Value, SYSDATETIME() FROM SomeSystemTableOrView; Of course, there are monitoring tools that will collect and manage this baseline data for you, automatically, and allow you to perform comparison of metrics over different periods. However, to get yourself started and to prove to yourself (or perhaps the person who writes the checks for tools) the value of baselines, stick something similar to the above query into an agent job, running every hour or so, and you are on your way with no excuses! Then, the next time you investigate a slow server, and see x open transactions, y users logged in, and z rows added per hour in the Orders table, compare to your baselines and see immediately what, if anything, has changed!

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• How to efficiently map tokens to code in a script interpreter?

  - by lithander

  I'm writing an interpreter for a simple scripting language where each line is a complete, executable command. (Like the instructions in assembler) When parsing a line I have to map the requested command to actual code. My current solution looks like this: std::string op, param1, param2; //parse line, identify op, param1, param2 ... //call command specific code if(op == "MOV") ExecuteMov(AsNumber(param1)); else if(op == "ROT") ExecuteRot(AsNumber(param1)); else if(op == "SZE") ExecuteSze(AsNumber(param1)); else if(op == "POS") ExecutePos((AsNumber(param1), AsNumber(param2)); else if(op == "DIR") ExecuteDir((AsNumber(param1), AsNumber(param2)); else if(op == "SET") ExecuteSet(param1, AsNumber(param2)); else if(op == "EVL") ... The more commands are supported the more string comparisions I'll have to do to identify and call the associated method. Can you point me to a more efficient implementation in the described scenario?

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• What is considered third party code?

  - by Songo

  Inspired by this question Using third-party libraries - always use a wrapper? I wanted to know what people actually consider as third-party libraries. Example from PHP: If I'm building an application using Zend framework, should I treat Zend framework libraries as third party code? Example from C#: If I'm building a desktop application, should I treat all .Net classes as third party code? Example from Java: Should I treat all libraries in the JDK as third party libraries? Some people say that if a library is stable and won't change often then one doesn't need to wrap it. However I fail to see how one would test a class that depends on a third party code without wrapping it.

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• Why after each restart, my local .NET sites take time to load for the first time?

  - by Saeed Neamati

  I'm developing sites based on .NET platform. I usually deploy these sites on my local IIS, so that I can test them and see their functionality before going live. However, each time I restart windows, it seems that sites take a long time to run for the first time. I know about JIT and I'm also aware of this question, but it doesn't answer my question. Does JIT happens every time you restart windows? Is it related to creation of w3wp.exe process? Why sites are so slow for the first request after each restart?

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• Slides and demo code for Columnstore Index session

  - by Hugo Kornelis

  Almost a week has passed after SQLBits X in London , so I guess it’s about time for me to share the slides and demo code of my session on columnstore indexes. After all, I promised people I would do that – especially when I found out that I had enough demos prepared to fill two sessions! I made some changes to the demo code. I added extra comments, not only to the demos I could not explain and run during the session, but also to the rest, so that people who missed the session will also be able to...(read more)

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• Metaobject protocol:Why is it known as an important concept

  - by sushant

  Metaobject protocol is protocol for metaobjects in a programming languages. Although I understand it on simple terms, I want to know the reason and a summary of real world usage patterns of this protocol. So, why exactly is metaobject and more importantly metaobject protocol is such a good idea. I want to know the problem which led to its evolution and also, its high power usage. Opinions as well as general overview/description/alternate explanations are also welcome.

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• Recommened design pattern to handle multiple compression algorithms for a class hierarchy

  - by sgorozco

  For all you OOD experts. What would be the recommended way to model the following scenario? I have a certain class hierarchy similar to the following one: class Base { ... } class Derived1 : Base { ... } class Derived2 : Base { ... } ... Next, I would like to implement different compression/decompression engines for this hierarchy. (I already have code for several strategies that best handle different cases, like file compression, network stream compression, legacy system compression, etc.) I would like the compression strategy to be pluggable and chosen at runtime, however I'm not sure how to handle the class hierarchy. Currently I have a tighly-coupled design that looks like this: interface ICompressor { byte[] Compress(Base instance); } class Strategy1Compressor : ICompressor { byte[] Compress(Base instance) { // Common compression guts for Base class ... // if( instance is Derived1 ) { // Compression guts for Derived1 class } if( instance is Derived2 ) { // Compression guts for Derived2 class } // Additional compression logic to handle other class derivations ... } } As it is, whenever I add a new derived class inheriting from Base, I would have to modify all compression strategies to take into account this new class. Is there a design pattern that allows me to decouple this, and allow me to easily introduce more classes to the Base hierarchy and/or additional compression strategies?

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