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  • Parallel programming patterns for C#?

    - by VoidDweller
    With Intel's launch of a Hexa-Core processor for the desktop, it looks like we can no longer wait for Microsoft to make many-core programming "easy". I just order a copy of Joe Duffy's book Concurrent Programming on Windows. This looks like a great place to start, though, I am hoping some of you who have been targeting multi/many core systems would point me to some good resources that have or would have helped on your projects?

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  • Mutability design patterns in Objective C and C++

    - by Mac
    Having recently done some development for iPhone, I've come to notice an interesting design pattern used a lot in the iPhone SDK, regarding object mutability. It seems the typical approach there is to define an immutable class NSFoo, and then derive from it a mutable descendant NSMutableFoo. Generally, the NSFoo class defines data members, getters and read-only operations, and the derived NSMutableFoo adds on setters and mutating operations. Being more familiar with C++, I couldn't help but notice that this seems to be a complete opposite to what I'd do when writing the same code in C++. While you certainly could take that approach, it seems to me that a more concise approach is to create a single Foo class, mark getters and read-only operations as const functions, and also implement the mutable operations and setters in the same class. You would then end up with a mutable class, but the types Foo const*, Foo const& etc all are effectively the immutable equivalent. I guess my question is, does my take on the situation make sense? I understand why Objective-C does things differently, but are there any advantages to the two-class approach in C++ that I've missed? Or am I missing the point entirely? Not an overly serious question - more for my own curiosity than anything else.

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  • Video Synthesis - Making waves, patterns, gradients...

    - by Nathan
    I'm writing a program to generate some wild visuals. So far I can paint each pixel with a random blue value: for (y = 0; y < YMAX; y++) { for (x = 0; x < XMAX; x++) { b = rand() % 255; setPixelColor(x,y,r,g,b); } } I'd like to do more than just make blue noise, but I'm not sure where to start (Google isn't helping me much today), so it would be great if you could share anything you know on the subject or some links to related resources.

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  • Design Layout/Patterns

    - by wpfwannabe
    I am still fairly new to C# and I am trying to decide the best way to structure a new program. Here is what I want to do and I would like feed back on my idea. Presentation Layer Business Layer (Separate Class Library) Data Layer (Separate Class Library) Model Layer (Separate Class Library) What I am struggling with is if it is ok to have the classes in the Data Layer and Business Layer inherit from the types I define in Model Layer. This way I can extended the types as needed in my Business Layer with any new properties I see fit. I might not use every property from the Model type in my Business Layer class but is that really a big deal? If this isn't clear enough I can try and put together an example.

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  • OO Design / Patterns - Fat Model Vs Transaction Script?

    - by ben
    Ok, 'Fat' Model and Transaction Script both solve design problems associated with where to keep business logic. I've done some research and popular thought says having all business logic encapsulated within the model is the way to go (mainly since Transaction Script can become really complex and often results in code duplication). However, how does this work if I want to use the TDG of a second Model in my business logic? Surely Transaction Script presents a neater, less coupled solution than using one Model inside the business logic of another? A practical example... I have two classes: User & Alert. When pushing User instances to the database (eg, creating new user accounts), there is a business rule that requires inserting some default Alerts records too (eg, a default 'welcome to the system' message etc). I see two options here: 1) Add this rule as a User method, and in the process create a dependency between User and Alert (or, at least, Alert's Table Data Gateway). 2) Use a Transaction Script, which avoids the dependency between models. (Also, means the business logic is kept in a 'neutral' class & easily accessible by Alert. That probably isn't too important here, though). User takes responsibility for it's own validation etc, however, but because we're talking about a business rule involving two Models, Transaction Script seems like a better choice to me. Anyone spot flaws with this approach?

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  • Custom Providers & Design Patterns

    - by Code Sherpa
    Hi. I am using ASP.NET 2.0 and its various providers. I have overridden most of the methods I need and have the following custom providers: ProjectMembershipProvider ProjectProfileProvider ProjectRoleProvider In the design of my project, my intention was to wrap the custom providers in a facade - style design - mixing and matching profiling, membership, and roles in API methods to simplify things for developers. But, I am finding that a lot of the methods in my custom providers don't need to change, really. And, it seems silly to wrap a stand-alone method in another method that does exactly the same thing. So - is my approach wrong? Or, should I allow end - users to instantiate the custom providers when needed and the mix/match api when needed? This seems a bit redundant to me but I can't see another way. Advice appreciated. Thanks.

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  • Design Patterns: What's the antithesis of Front Controller?

    - by Brian Lacy
    I'm familiar with the Front Controller pattern, in which all events/requests are processed through a single centralized controller. But what would you call it when you wish to keep the various parts of an application separate at the presentation layer as well? My first thought was "Facade" but it turns out that's something entirely different. In my particular case, I'm converting an application from a sprawling procedural mess to a clean MVC architecture, but it's a long-term process -- we need to keep things separated as much as possible to facilitate a slow integration with the rest of the system. Our application is web-based, built in PHP, so for instance, we have an "index.php" and an IndexController, a "account.php" and an AccountController, a "dashboard.php" and DashboardController, and so on.

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  • Session Report - Modern Software Development Anti-Patterns

    - by Janice J. Heiss
    In this standing-room-only session, building upon his 2011 JavaOne Rock Star “Diabolical Developer” session, Martijn Verburg, this time along with Ben Evans, identified and explored common “anti-patterns” – ways of doing things that keep developers from doing their best work. They emphasized the importance of social interaction and team communication, along with identifying certain psychological pitfalls that lead developers astray. Their emphasis was less on technical coding errors and more how to function well and to keep one’s focus on what really matters. They are the authors of the highly regarded The Well-Grounded Java Developer and are both movers and shakers in the London JUG community and on the Java Community Process. The large room was packed as they gave a fast-moving, witty presentation with lots of laughs and personal anecdotes. Below are a few of the anti-patterns they discussed.Anti-Pattern One: Conference-Driven DeliveryThe theme here is the belief that “Real pros hack code and write their slides minutes before their talks.” Their response to this anti-pattern is an expression popular in the military – PPPPPP, which stands for, “Proper preparation prevents piss-poor performance.”“Communication is very important – probably more important than the code you write,” claimed Verburg. “The more you speak in front of large groups of people the easier it gets, but it’s always important to do dry runs, to present to smaller groups. And important to be members of user groups where you can give presentations. It’s a great place to practice speaking skills; to gain new skills; get new contacts, to network.”They encouraged attendees to record themselves and listen to themselves giving a presentation. They advised them to start with a spouse or friends if need be. Learning to communicate to a group, they argued, is essential to being a successful developer. The emphasis here is that software development is a team activity and good, clear, accessible communication is essential to the functioning of software teams. Anti-Pattern Two: Mortgage-Driven Development The main theme here was that, in a period of worldwide recession and economic stagnation, people are concerned about keeping their jobs. So there is a tendency for developers to treat knowledge as power and not share what they know about their systems with their colleagues, so when it comes time to fix a problem in production, they will be the only one who knows how to fix it – and will have made themselves an indispensable cog in a machine so you cannot be fired. So developers avoid documentation at all costs, or if documentation is required, put it on a USB chip and lock it in a lock box. As in the first anti-pattern, the idea here is that communicating well with your colleagues is essential and documentation is a key part of this. Social interactions are essential. Both Verburg and Evans insisted that increasingly, year by year, successful software development is more about communication than the technical aspects of the craft. Developers who understand this are the ones who will have the most success. Anti-Pattern Three: Distracted by Shiny – Always Use the Latest Technology to Stay AheadThe temptation here is to pick out some obscure framework, try a bit of Scala, HTML5, and Clojure, and always use the latest technology and upgrade to the latest point release of everything. Don’t worry if something works poorly because you are ahead of the curve. Verburg and Evans insisted that there need to be sound reasons for everything a developer does. Developers should not bring in something simply because for some reason they just feel like it or because it’s new. They recommended a site run by a developer named Matt Raible with excellent comparison spread sheets regarding Web frameworks and other apps. They praised it as a useful tool to help developers in their decision-making processes. They pointed out that good developers sometimes make bad choices out of boredom, to add shiny things to their CV, out of frustration with existing processes, or just from a lack of understanding. They pointed out that some code may stay in a business system for 15 or 20 years, but not all code is created equal and some may change after 3 or 6 months. Developers need to know where the code they are contributing fits in. What is its likely lifespan? Anti-Pattern Four: Design-Driven Design The anti-pattern: If you want to impress your colleagues and bosses, use design patents left, right, and center – MVC, Session Facades, SOA, etc. Or the UML modeling suite from IBM, back in the day… Generate super fast code. And the more jargon you can talk when in the vicinity of the manager the better.Verburg shared a true story about a time when he was interviewing a guy for a job and asked him what his previous work was. The interviewee said that he essentially took patterns and uses an approved book of Enterprise Architecture Patterns and applied them. Verburg was dumbstruck that someone could have a job in which they took patterns from a book and applied them. He pointed out that the idea that design is a separate activity is simply wrong. He repeated a saying that he uses, “You should pay your junior developers for the lines of code they write and the things they add; you should pay your senior developers for what they take away.”He explained that by encouraging people to take things away, the code base gets simpler and reflects the actual business use cases developers are trying to solve, as opposed to the framework that is being imposed. He told another true story about a project to decommission a very long system. 98% of the code was decommissioned and people got a nice bonus. But the 2% remained on the mainframe so the 98% reduction in code resulted in zero reduction in costs, because the entire mainframe was needed to run the 2% that was left. There is an incentive to get rid of source code and subsystems when they are no longer needed. The session continued with several more anti-patterns that were equally insightful.

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  • Patterns to implement this grammar into C# code

    - by MexicanHacker
    Hey guys, I'm creating this little BNF grammar and I wanted to <template>::= <types><editors> <types>::= <type>+ <type>::= <property>+ <property>::= <name><type> <editors>::= <editor>+ <editor>::= <name><type>(<textfield>|<form>|<list>|<pulldown>)+ <textfield>::= <label><property>[<editable>] <form>::= <label><property><editor> <list>::= <label><property><item-editor> <pulldown>::= <label><property><option>+ <option>::= <value> One possible solution we have in mind is to create POCO's that have annotations of the XMLSerialization namespace, like this, for example: [XMLRoot("template")] public class Template{ [XMLElement("types")] public Types types{ } } However I want to explore more solutions, what do you guys think?

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  • C# Design Layout/Patterns

    - by wpfwannabe
    I am still fairly new to C# and I am trying to decide the best way to structure a new program. Here is what I want to do and I would like feed back on my idea. Presentation Layer Business Layer (Separate Class Library) Data Layer (Separate Class Library) Model Layer (Separate Class Library) What I am struggling with is if it is ok to have the classes in the Data Layer and Business Layer inherit from the types I define in Model Layer. This way I can extended the types as needed in my Business Layer with any new properties I see fit. I might not use every property from the Model type in my Business Layer class but is that really a big deal? If this isn't clear enough I can try and put together an example.

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  • DoFactory Architecture Design

    - by Brendan Vogt
    Hi, Has anybody used the Patterns in Action from the Do Factory? I just have a question on the architecture. I always thought that the service must call the repository. In the solution the have ActionService and a repository. Lets say I want to get all the customers then in my controller I would call the repository's GetCustomers method. This will then call ActionService's GetCustomer's method. And then lastly another GetCustomers method is called in the customer data access object. Is this right? Any comments on the way that they implemented things in the Patterns in Action?

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  • iPhone development - app design patterns

    - by occulus
    There are tons of resources concerning coding on the iPhone. Most of them concern "how do I do X", e.g. "setup a navigation controller", or "download text from a URL". All good and fine. What I'm more interested in now are the questions that follow the simpler stuff - how to best structure your complex UI, or your app, or the common problems that arise. To illustrate: a book like "Beginning iPhone 3 Development" tells you how to set up a multi viewcontroller app with an top 'switcher' viewcontroller that switches between views owned by other view controllers. Fine, but you're only told how to do that, and nothing about the problems that can follow: for example, if I use their paradigm to switch to a UINavigationViewController, the Navigation bar ends up too low on the screen, because UINavigationViewController expects to be the topmost UIViewController (apparently). Also, delegate methods (e.g. relating to orientation changes) go to the top switcher view controller, not the actual controller responsible for the current view. I have fixes for these things but they feel like hacks which makes me unhappy and makes me feel like I'm missing something. One productive thing might be to look at some open source iPhone projects (see this question). But aside from that?

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  • What are the common patterns in web programming?

    - by lankerisms
    I have been trying to write my first big web app (more than one cgi file) and as I kept moving forward with the rough prototype, paralelly trying to predict more tasks, this is the todo that got accumulated (In no particular order). * Validations and input sanitizations * Object versioning (to avoid edit conflicts. I dont want hard locks) * Exception handling * memcache * xss and injection protections * javascript * html * ACLs * phonetics in search, match and find duplicates (for form validation) * Ajaxify!!! (I have snipped off the project specific items.) I know that each todo will be quite tied up to its project and technologies used. What I am wondering though, is if there is a pattern in your todo items as well as the sequence in which you experienced guys have come across them.

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  • Finding shapes in 2D Array, then optimising

    - by assemblism
    I'm new so I can't do an image, but below is a diagram for a game I am working on, moving bricks into patterns, and I currently have my code checking for rotated instances of a "T" shape of any colour. The X and O blocks would be the same colour, and my last batch of code would find the "T" shape where the X's are, but what I wanted was more like the second diagram, with two "T"s Current result      Desired Result [X][O][O]                [1][1][1] [X][X][_]                [2][1][_] [X][O][_]                [2][2][_] [O][_][_]                [2][_][_] My code loops through x/y, marks blocks as used, rotates the shape, repeats, changes colour, repeats. I have started trying to fix this checking with great trepidation. The current idea is to: loop through the grid and make note of all pattern occurrences (NOT marking blocks as used), and putting these to an array loop through the grid again, this time noting which blocks are occupied by which patterns, and therefore which are occupied by multiple patterns. looping through the grid again, this time noting which patterns obstruct which patterns That much feels right... What do I do now? I think I would have to try various combinations of conflicting shapes, starting with those that obstruct the most other patterns first.How do I approach this one? use the rational that says I have 3 conflicting shapes occupying 8 blocks, and the shapes are 4 blocks each, therefore I can only have a maximum of two shapes. (I also intend to incorporate other shapes, and there will probably be score weighting which will need to be considered when going through the conflicting shapes, but that can be another day) I don't think it's a bin packing problem, but I'm not sure what to look for. Hope that makes sense, thanks for your help

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  • Are there any well known anti-patterns in the field of system administration?

    - by ojblass
    I know a few common patterns that seem to bedevil nearly every project at some point in its life cycle: Inability to take outages Third party components locking out upgrades Non uniform environments Lack of monitoring and alerting Missing redundancy Lack of Capacity Poor Change Management Too liberal or tight access policies Organizational changes adversely blur infrastructure ownership I was hoping there is some well articulated library of these anti-patterns summarized in a book or web site. I am almost positive that many organizations are learning through trial by fire methods. If not let's start one.

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  • Comparison of Architecture presentation patterns MVP(SC),MVP(PV),PM,MVVM and MVC

    This article will compare four important architecture presentation patterns i.e. MVP(SC),MVP(PV),PM,MVVM and MVC. Many developers are confused around what is the difference between these patterns and when should we use what. This article will first kick start with a background and explain different...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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  • Comparison of Architecture presentation patterns MVP(SC),MVP(PV),PM,MVVM and MVC

    This article will compare four important architecture presentation patterns i.e. MVP(SC),MVP(PV),PM,MVVM and MVC. Many developers are confused around what is the difference between these patterns and when should we use what. This article will first kick start with a background and explain different...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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  • Vermeidung von SOA Anti-Patterns mittels AIA

    - by Hans Viehmann
    Gerade ist mir ein White Paper des Enterprise Architecture Teams in die Hände gefallen, das sich mit SOA Anti-Patterns befasst. Es ist zwar kein AIA Paper im eigentlichen Sinne, aber mit AIA hat man natürlich eine gute Unterstützung darin, die dort beschriebenen Fehler zu vermeiden. Das White Paper behandelt Themen wie: Vermeidung von SOA Silos SOA Reifegrad und Projekt-Management Ausuferndes Service Portfolio Umgang mit Referenz-Architekturen EAI 2.0 - Punkt-zu-Punkt Integration auf offenen Standards Ein Link auf das Dokument ist unten angefügt - viel Vergnügen bei der Lektüre ... Oracle White Paper: SOA Anti-Patterns.

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  • Google I/O 2012 - Playing with Patterns

    Google I/O 2012 - Playing with Patterns "Marco Paglia Best-in-class application designers and developers will talk about their experience in developing for Android, showing screenshots from their app, exploring the challenges they faced, and offering creative solutions congruent with the Android Design guide. Guests will be invited to show examples of visual and interaction patterns in their application that manage to keep it simultaneously consistent and personal. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 1 0 ratings Time: 02:13:20 More in Science & Technology

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  • Google I/O 2012 - Knowledge-Based Application Design Patterns

    Google I/O 2012 - Knowledge-Based Application Design Patterns Shawn Simister In this talk we'll look at emerging design patterns for building web applications that take advantage of large-scale, structured data. We'll look at open datasets like Wikipedia and Freebase as well as structured markup like Schema.org and RDFa to see what new types of applications these technologies open up for developers. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 1 0 ratings Time: 56:55 More in Science & Technology

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  • Protobuf design patterns

    - by Monster Truck
    I am evaluating Google Protocol Buffers for a Java based service (but am expecting language agnostic patterns). I have two questions: The first is a broad general question: What patterns are we seeing people use? Said patterns being related to class organization (e.g., messages per .proto file, packaging, and distribution) and message definition (e.g., repeated fields vs. repeated encapsulated fields*) etc. There is very little information of this sort on the Google Protobuf Help pages and public blogs while there is a ton of information for established protocols such as XML. I also have specific questions over the following two different patterns: Represent messages in .proto files, package them as a separate jar, and ship it to target consumers of the service --which is basically the default approach I guess. Do the same but also include hand crafted wrappers (not sub-classes!) around each message that implement a contract supporting at least these two methods (T is the wrapper class, V is the message class (using generics but simplified syntax for brevity): public V toProtobufMessage() { V.Builder builder = V.newBuilder(); for (Item item : getItemList()) { builder.addItem(item); } return builder.setAmountPayable(getAmountPayable()). setShippingAddress(getShippingAddress()). build(); } public static T fromProtobufMessage(V message_) { return new T(message_.getShippingAddress(), message_.getItemList(), message_.getAmountPayable()); } One advantage I see with (2) is that I can hide away the complexities introduced by V.newBuilder().addField().build() and add some meaningful methods such as isOpenForTrade() or isAddressInFreeDeliveryZone() etc. in my wrappers. The second advantage I see with (2) is that my clients deal with immutable objects (something I can enforce in the wrapper class). One disadvantage I see with (2) is that I duplicate code and have to sync up my wrapper classes with .proto files. Does anyone have better techniques or further critiques on any of the two approaches? *By encapsulating a repeated field I mean messages such as this one: message ItemList { repeated item = 1; } message CustomerInvoice { required ShippingAddress address = 1; required ItemList = 2; required double amountPayable = 3; } instead of messages such as this one: message CustomerInvoice { required ShippingAddress address = 1; repeated Item item = 2; required double amountPayable = 3; } I like the latter but am happy to hear arguments against it.

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  • How to start recognizing design patterns as you are programming?

    - by Jon Erickson
    I have general academic knowledge of the various design patterns that are discussed in GoF and Head First Design Patterns, but I have a difficult time applying them to the code that I am writing. A goal for me this year is to be able to recognize design patterns that are emerging from the code that I write. Obviously this comes with experience (I have about 2 years in the field), but my question is how can I jumpstart my ability to recognize design patterns as I am coding, maybe a suggestion as to what patterns are easiest to start applying in client-server applications (in my case mainly c# webforms with ms sql db's, but this could definitely be language agnostic).

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