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• Thoughts on Nexus in SQL Server PDW

  - by jamiet

  I have been on a SQL Server Parallel Data Warehouse (aka PDW) training course this week and was interested to learn that you can't (yet) use SQL Server Management Studio (SSMS) against PDW, instead they ship a 3rd party tool called Nexus Chameleon. This was a bit of a disappointment at the beginning of the week (I'd prefer parity across SQL Server editions) but actually, having used Nexus for 3 days, I'm rather getting used to it. Some of it is a bit clunky (e.g. everything goes via an ODBC DSN) but once you get into using it its the epitome of "it just works". For example, over the past few years I have come to rely on intellisense in SSMS and have learnt to cope with its nuances. There is no intellisense in Nexus but you know what....I don't really miss it that much. In a sense its a breath of fresh air not having to hope that you've crossed the line into that will it work/won't it work grey area with SSMS intellisense. And I don't end up with writing @@CONNECTIONS instead of FROM anymore (anyone else suffer from this?) :) Moreover, Nexus is a standalone tool. Its not a bunch of features shoehorned into something else (Visual Studio). Another thing I like about Nexus is that you can actually do something with your resultset client-side. Take a look at the screenshots below:   You can see Nexus allows you to group a resultest by a column or set of columns. Nice touch. I know that many people have submitted Connect requests asking for the ability to do similar things in SSMS that would mean we don't have to copy resultsets into Excel (I know I have) - Nexus is a step in that direction. Its refreshing to use a tool that just gets out of the way yet still has some really useful features. How ironic that it gets shipped inside an edition of SQL Server! If I had the option of using Nexus in my day job I suspect that over time I would probably gravitate back to SSMS because as yet I haven’t really stretched Nexus’ capabilities, overall SSMS *does* have more features and up until now I've never really had any objections to it ... but its been an interesting awakening into the nuances that plague SSMS. Anyone else used Nexus? Any thoughts on it? @Jamiet

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• SSAS deployment error: Internal error: Invalid enumeration value. Please call customer support! is not a valid value for this element.

  - by Kevin Shyr

  The first search on this error yielded some blog posts that says to check SQL server version.  It suggested that I couldn't deploy a SSAS project originally set for SSAS 2008 to a SSAS 2008 R2, which didn't make sense to me.  Combined with the fact that the error message was telling me to call customer support.  Why do I need to call customer support unless something catastrophic happened?Turns out that one of the file on the SQL server is corrupt.  I could simply delete the database on the SSAS server and re-run deployment.  Problem solved.SSAS errors in visual studio: Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Error      10           Internal error: Invalid enumeration value. Please call customer support! is not a valid value for this element.                                0              0              Error      11           An error occurred while parsing the 'StorageMode' element at line 1, column 10523 ('http://schemas.microsoft.com/analysisservices/2003/engine' namespace) under Load/ObjectDefinition/Dimension/StorageMode.                            0              0              Error      12           Errors in the metadata manager. An error occurred when instantiating a metadata object from the file, '\\?\E:\Program Files\Microsoft SQL Server\MSAS10_50.MSSQLSERVER\OLAP\Data\DWH Sales Facts.0.db\Competitor.48.dim.xml'.                        0              0

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• AI for a mixed Turn Based + Real Time battle system - Something "Gambit like" the right approach?

  - by Jason L.

  This is maybe a question that's been asked 100 times 1,000 different ways. I apologize for that :) I'm in the process of building the AI for a game I'm working on. The game is a turn based one, in the vein of Final Fantasy but also has a set of things that happen in real time (reactions). I've experimented with FSM, HFSMs, and Behavior Trees. None of them felt "right" to me and all felt either too limiting or too generic / big. The idea I'm toying with now is something like a "Rules engine" that could be likened to the Gambit system from Final Fantasy 12. I would have a set of predefined personalities. Each of these personalities would have a set of conditions it would check on each event (Turn start, time to react, etc). These conditions would be priority ordered, and the first one that returns true would be the action I take. These conditions can also point to a "choice" action, which is just an action that will make a choice based on some Utility function. Sort of a mix of FSM/HFSM and a Utility Function approach. So, a "gambit" with the personality of "Healer" may look something like this: (ON) Ally HP = 0% - Choose "Relife" spell (ON) Ally HP < 50% - Choose Heal spell (ON) Self HP < 65% - Choose Heal spell (ON) Ally Debuff - Choose Debuff Removal spell (ON) Ally Lost Buff - Choose Buff spell Likewise, a "gambit" with the personality of "Agressor" may look like this: (ON) Foe HP < 10% - Choose Attack skill (ON) Foe any - Choose target - Choose Attack skill (ON) Self Lost Buff - Choose Buff spell (ON) Foe HP = 0% - Taunt the player What I like about this approach is it makes sense in my head. It also would be extremely easy to build an "AI Editor" with an approach like this. What I'm worried about is.. would it be too limiting? Would it maybe get too complicated? Does anyone have any experience with AIs in Turn Based games that could maybe provide me some insight into this approach.. or suggest a different approach? Many thanks in advance!!!

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• Where and how to reference composite MVP components?

  - by Lea Hayes

  I am learning about the MVP (Model-View-Presenter) Passive View flavour of MVC. I intend to expose events from view interfaces rather than using the observer pattern to remove explicit coupling with presenter. Context: Windows Forms / Client-Side JavaScript. I am led to believe that the MVP (or indeed MVC in general) pattern can be applied at various levels of a user interface ranging from the main "Window" to an embedded "Text Field". For instance, the model to the text field is probably just a string whereas the model to the "Window" contains application specific view state (like a persons name which resides within the contained text field). Given a more complex scenario: Documentation viewer which contains: TOC navigation pane Document view Search pane Since each of these 4 user interface items are complex and can be reused elsewhere it makes sense to design these using MVP. Given that each of these user interface items comprises of 3 components; which component should be nested? where? who instantiates them? Idea #1 - Embed View inside View from Parent View public class DocumentationViewer : Form, IDocumentationViewerView { public DocumentationViewer() { ... // Unclear as to how model and presenter are injected... TocPane = new TocPaneView(); } protected ITocPaneView TocPane { get; private set; } } Idea #2 - Embed Presenter inside View from Parent View public class DocumentationViewer : Form, IDocumentationViewerView { public DocumentationViewer() { ... // This doesn't seem like view logic... var tocPaneModel = new TocPaneModel(); var tocPaneView = new TocPaneView(); TocPane = new TocPanePresenter(tocPaneModel, tocPaneView); } protected TocPanePresenter TocPane { get; private set; } } Idea #3 - Embed View inside View from Parent Presenter public class DocumentationViewer : Form, IDocumentationViewerView { ... // Part of IDocumentationViewerView: public ITocPaneView TocPane { get; set; } } public class DocumentationViewerPresenter { public DocumentationViewerPresenter(DocumentationViewerModel model, IDocumentationViewerView view) { ... var tocPaneView = new TocPaneView(); var tocPaneModel = new TocPaneModel(model.Toc); var tocPanePresenter = new TocPanePresenter(tocPaneModel, tocPaneView); view.TocPane = tocPaneView; } } Some better idea...

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• Will my self-taught code be fine, or should I take it to the professional level?

  - by G1i1ch

  Lately I've been getting professional work, hanging out with other programmers, and making friends in the industry. The only thing is I'm 100% self-taught. It's caused my style to extremely deviate from the style of those that are properly trained. It's the techniques and organization of my code that's different. It's a mixture of several things I do. I tend to blend several programming paradigms together. Like Functional and OO. I lean to the Functional side more than OO, but I see the use of OO when something would make more sense as an abstract entity. Like a game object. Next I also go the simple route when doing something. When in contrast, it seems like sometimes the code I see from professional programmers is complicated for the sake of it! I use lots of closures. And lastly, I'm not the best commenter. I find it easier just to read through my code than reading the comment. And most cases I just end up reading the code even if there are comments. Plus I've been told that, because of how simply I write my code, it's very easy to read it. I hear professionally trained programmers go on and on about things like unit tests. Something I've never used before so I haven't even the faintest idea of what they are or how they work. Lots and lots of underscores "_", which aren't really my taste. Most of the techniques I use are straight from me, or a few books I've read. Don't know anything about MVC, I've heard a lot about it though with things like backbone.js. I think it's a way to organize an application. It just confuses me though because by now I've made my own organizational structures. It's a bit of a pain. I can't use template applications at all when learning something new like with Ubuntu's Quickly. I have trouble understanding code that I can tell is from someone trained. Complete OO programming really leaves a bad taste in my mouth, yet that seems to be what EVERYONE else is strictly using. It's left me not that confident in the look of my code, or wondering whether I'll cause sparks when joining a company or maybe contributing to open source projects. In fact I'm rather scared of the fact that people will eventually be checking out my code. Is this just something normal any programmer goes through or should I really look to change up my techniques?

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• Favorite moments of JavaOne

  - by Tori Wieldt

  There are so many events and sessions to attend at JavaOne, it's unfair to ask people to choose just one thing they liked, but here are some favorite moments: I loved meeting many open source contributors and friends I have not met in person before and seeing that projects like e.g. Hudson are alive and kicking and have a great future ahead of them. -Manfred Moser My "The Problem with Women" session. It had LOADS of interactivity from the audience, who really helped to make that session.  I came out if it with a real sense of optimism - we love our jobs, we love what we do, and we should be proud of telling everyone about it to attract different talent into the industry. (Read her blog JavaOne: The Problem With Women - A Technical Approach for details.) -Trish Gee My kudos to Oracle for making the presentation materials quickly available to the public. Some of them were already available during JavaOne. Lots of slide decks are already there, and in some cases you may even find the video recordings too. Go to http://www.oracle.com/javaone and select JavaOne Technical Sessions.  -Yakov Fain I loved that not only was James Gosling present at the Community Keynote (which felt more like the keynotes of old times [big space, big screens, fun and tech]) but he was also found wandering the halls of the Hilton the day prior. Bring back James! Add back the toys section in the Community Keynote. Let the t-shirt tossing begin anew. These are "small" things that really fire up the community. -Andres Almiray Seeing James Gosling at JavaOne was a real shot in the arm for Java.  He needs to be there every year. -Frank Greco +42 on having James and the T-shirt tossing. -Stephan Janssen The session "Integrate Java with Robots, Home Automation, Musical Instruments, and Kinect." Fabiane Nardon explained connecting Jenkins to jHome to a truck horn placed in their sysadmin's bedroom. She dubbed it "extreme feedback."  -Tori Wieldt The User Group Forum [on Sunday] was a success! Congratulations Bruno Souza and John Yeary and everybody that were involved. I believe it really helps to increase community participation! There were lots of interesting talks, and great discussion with JUG leaders and members. Thank you Oracle for supporting that! -Yara Senger What was your favorite moment? Please comment! 

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• Transparent Technology from Amazon

  - by David Dorf

  Amazon has been making some interesting moves again, this time in the augmented humanity area.  Augmented humanity is about helping humans overcome their shortcomings using technology.  Putting a powerful smartphone in your pocket helps you in many ways like navigating streets, communicating with far off friends, and accessing information.  But the interface for smartphones is somewhat limiting and unnatural, so companies have been looking for ways to make the technology more transparent and therefore easier to use. When Apple helped us drop the stylus, we took a giant leap forward in simplicity.  Using touchscreens with intuitive gestures was part of the iPhone's original appeal.  People don't want to know that technology is there -- they just want the benefits.  So what's the next leap beyond the touchscreen to make smartphones even easier to use? Two natural ways we interact with the world around us is by using sight and voice.  Google and Apple have been using both in their mobile platforms for limited uses cases.  Nobody actually wants to type a text message, so why not just speak it?  Any if you want more information about a book, why not just snap a picture of the cover?  That's much more accurate than trying to key the title and/or author. So what's Amazon been doing?  First, Amazon released a new iPhone app called Flow that allows iPhone users to see information about products in context.  Yes, its an augmented reality app that uses the phone's camera to view products, and overlays data about the products on the screen.  For the most part it requires the barcode to be visible to correctly identify the product, but I believe it can also recognize certain logos as well.  Download the app and try it out but don't expect perfection.  Its good enough to demonstrate the concept, but its far from accurate enough.  (MobileBeat did a pretty good review.)  Extrapolate to the future and we might just have a heads-up display in our eyeglasses. The second interesting area is voice response, for which Siri is getting lots of attention.  Amazon may have purchased a voice recognition company called Yap, although the deal is not confirmed.  But it would make perfect sense, especially with the Kindle Fire in Amazon's lineup. I believe over the next 3-5 years the way in which we interact with smartphones will mature, and they will become more transparent yet more important to our daily lives.  This will, of course, impact the way we shop, making information more readily accessible than it already is.  Amazon seems to be positioning itself to be at the forefront of this trend, so we should be watching them carefully.

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• Interviews: Going Beyond the Technical Quiz

  - by Tony Davis

  All developers will be familiar with the basic format of a technical interview. After a bout of CV-trawling to gauge basic experience, strengths and weaknesses, the interview turns technical. The whiteboard takes center stage and the challenge is set to design a function or query, or solve what on the face of it might seem a disarmingly simple programming puzzle. Most developers will have experienced those few panic-stricken moments, when one’s mind goes as blank as the whiteboard, before un-popping the marker pen, and hopefully one’s mental functions, to work through the problem. It is a way to probe the candidate’s knowledge of basic programming structures and techniques and to challenge their critical thinking. However, these challenges or puzzles, often devised by some of the smartest brains in the development team, have a tendency to become unnecessarily ‘tricksy’. They often seem somewhat academic in nature. While the candidate straight out of IT school might breeze through the construction of a Markov chain, a candidate with bags of practical experience but less in the way of formal training could become nonplussed. Also, a whiteboard and a marker pen make up only a very small part of the toolkit that a programmer will use in everyday work. I remember vividly my first job interview, for a position as technical editor. It went well, but after the usual CV grilling and technical questions, I was only halfway there. Later, they sat me alongside a team of editors, in front of a computer loaded with MS Word and copy of SQL Server Query Analyzer, and my task was to edit a real chapter for a real SQL Server book that they planned to publish, including validating and testing all the code. It was a tough challenge but I came away with a sound knowledge of the sort of work I’d do, and its context. It makes perfect sense, yet my impression is that many organizations don’t do this. Indeed, it is only relatively recently that Red Gate started to move over to this model for developer interviews. Now, instead of, or perhaps in addition to, the whiteboard challenges, the candidate can expect to sit with their prospective team, in front of Visual Studio, loaded with all the useful tools in the developer’s kit (ReSharper and so on) and asked to, for example, analyze and improve a real piece of software. The same principles should apply when interviewing for a database positon. In addition to the usual questions challenging the candidate’s knowledge of such things as b-trees, object permissions, database recovery models, and so on, sit the candidate down with the other database developers or DBAs. Arm them with a copy of Management Studio, and a few other tools, then challenge them to discover the flaws in a stored procedure, and improve its performance. Or present them with a corrupt database and ask them to get the database back online, and discover the cause of the corruption.

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• Working with EO composition associations via ADF BC SDO web services

  - by Chris Muir

  ADF Business Components support the ability to publish the underlying Application Modules (AMs) and View Objects (VOs) as web services through Service Data Objects (SDOs).  This blog post looks at a minor challenge to overcome when using SDOs and Entity Objects (EOs) that use a composition association. Using the default ADF BC EO association behaviour ADF BC components allow you to work with VOs that are based on EOs that are a part of a parent-child composition association.  A composition association enforces that you cannot create records for the child outside the context of the parent.  As example when creating invoice-lines you want to enforce the individual lines have a relating parent invoice record, it just simply doesn't make sense to save invoice-lines without their parent invoice record. In the following screenshot using the ADF BC Tester it demonstrates the correct way to create a child Employees record as part of a composition association with Departments: And the following screenshot shows you the wrong way to create an Employee record: Note the error which is enforced by the composition association: (oracle.jbo.InvalidOwnerException) JBO-25030: Detail entity Employees with row key null cannot find or invalidate its owning entity.  Working with composition associations via the SDO web services  Shay Shmeltzer recently recorded a good video which demonstrates how to expose your ADF Business Components through the SDO interface. On exposing the VOs you get a choice of operation to publish including create, update, delete and more: For example through the SDO test interface we can see that the create operation will request the attributes for the VO exposed, in this case EmployeesView1: In this specific case though, just like the ADF BC Tester, an attempt to create this record will fail with JBO-25030, the composition association is still enforced: The correct way to to do this is through the create operation on the DepartmentsView1 which also lets you create employees record in context of the parent, thus satisfying the composition association rule: Yet at issue here is the create operation will always create both the parent Departments and Employees records.  What do we do if we've already previously created the parent Departments records, and we just want to create additional Employees records for that Department?  The create method of the EmployeeView1 as we saw previously doesn't allow us to do that, the JBO-3050 error will be raised. The solution is the "merge" operation on the parent Departments record: In this case for the Departments record you just need to supply the DepartmentId of the Department you want the Employees record to be associated with, as well as the new Employees record.  When invoked only the Employees record is created, and the supply of the DepartmentId of the Departments record satisfies the composition association without actually creating or updating the associated Department record that already exists in the database. Be warned however if you supply any more attributes for the Department record, it will result in a merge (update) of the associated Departments record too. 

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• Game development: “Play Now” via website vs. download & install

  - by Inside

  Heyo, I've spent some time looking over the various threads here on gamedev and also on the regular stackoverflow and while I saw a lot of posts and threads regarding various engines that could be used in game development, I haven't seen very much discussion regarding the various platforms that they can be used on. In particular, I'm talking about browser games vs. desktop games. I want to develop a simple 3D networked multiplayer game - roughly on the graphics level of Paper Mario and gameplay with roughly the same level of interaction as a hack & slash action/adventure game - and I'm having a hard time deciding what platform I want to target with it. I have some experience with using C++/Ogre3D and Python/Panda3D (and also some synchronized/networked programming), but I'm wondering if it's worth it to spend the extra time to learn another language and another engine/toolkit just so that the game can be played in a browser window (I'm looking at jMonkeyEngine right now). For simple & short games the newgrounds approach (go to the site, click "play now", instant gratification) seems to work well. What about for more complex games? Is there a point where the complexity of a game is enough for people to say "ok, I'm going to download and play that"? Is it worth it to go with engines that are less-mature, have less documentation, have fewer features, and smaller communities* just so that a (possibly?) larger audience can be reached? Does it make sense to even go with a web-environment for the kind of game that I want to make? Does anyone have any experiences with decisions like this? Thanks! (* With the exception of flash-based engines it seems like most of the other approaches have these downsides when compared to what is available for desktop-based environments. I'd go with flash, but I'm worried that flash's 3D capabilities aren't mature enough right now to do what I want easily. There's also Unity3D, but I'm not sure how I feel about that at all. It seems highly polished, but requires a plugin to be downloaded for the game to be played -- at that rate I might as well have players download my game.)

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• Where are my sub templates?

  - by Tim Dexter

  This one is for standalone/BIEE uses of Publisher. All the ERP/CRM/HCM folks are already catered for and can tuck into a nut cutlet and arugala salad. Sorry, I have just watched Food Inc and even if only half of it is true; Im still on a crusade in my house against mass produced food. Wake up World! If you have ventured into the world of sub templating, you'll be reaping some development benefit. In terms of shared report components and calculations they are very useful. Just exporting all of your report headers and footers to a single sub template can potentially save you hours and hours of work and make you look like a star. If someone in management gets it into their head that they would like Comic San Serif font rather than Arial in their report headers, its a 10 min job rather than 100 hours! What about the rest of the report content? I hear you cry. Its coming in 11g, full master template support. Your management wants bright blue borders with yellow backgrounds for all the tables in your reports, 5 minute job! Getting back to sub templates and my comment about all the ERP/CRM/HCM folks be catered for. In the standalone release there is no out of the box directory for you to drop your sub templates. Dropping them into the main report directory would make sense but they are not accessible there via a URL. An oversight on our part and something that will be addressed in 11g. Sub templates are now a first class citizen in the world of BIP, you can upload them and BIP will know what to do with them. But what do you do right now? The easiest place to put them where BIP can 'see' them is to create a directory under the xmlpserver install directory in the J2EE container e.g. $J2EE_HOME/xmlpserver/xmlpserver/subtemplates You can call it whatever you want but when the server is started up, that directory is accessible via a URL i.e. http://tdexter:9704/xmlpserver/subtemplates/mysub.rtf. You can therefore put it into the top of your main templates and call the sub template. <?import: http://tdexter:9704/xmlpserver/subtemplates/mysub.rtf?> Of course, you can drop them anywhere you want, they just need to be in a web server mountable directory. Enjoy the arugala!

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• What is a better abstraction layer for D3D9 and OpenGL vertex data management?

  - by Sam Hocevar

  My rendering code has always been OpenGL. I now need to support a platform that does not have OpenGL, so I have to add an abstraction layer that wraps OpenGL and Direct3D 9. I will support Direct3D 11 later. TL;DR: the differences between OpenGL and Direct3D cause redundancy for the programmer, and the data layout feels flaky. For now, my API works a bit like this. This is how a shader is created: Shader *shader = Shader::Create( " ... GLSL vertex shader ... ", " ... GLSL pixel shader ... ", " ... HLSL vertex shader ... ", " ... HLSL pixel shader ... "); ShaderAttrib a1 = shader->GetAttribLocation("Point", VertexUsage::Position, 0); ShaderAttrib a2 = shader->GetAttribLocation("TexCoord", VertexUsage::TexCoord, 0); ShaderAttrib a3 = shader->GetAttribLocation("Data", VertexUsage::TexCoord, 1); ShaderUniform u1 = shader->GetUniformLocation("WorldMatrix"); ShaderUniform u2 = shader->GetUniformLocation("Zoom"); There is already a problem here: once a Direct3D shader is compiled, there is no way to query an input attribute by its name; apparently only the semantics stay meaningful. This is why GetAttribLocation has these extra arguments, which get hidden in ShaderAttrib. Now this is how I create a vertex declaration and two vertex buffers: VertexDeclaration *decl = VertexDeclaration::Create( VertexStream<vec3,vec2>(VertexUsage::Position, 0, VertexUsage::TexCoord, 0), VertexStream<vec4>(VertexUsage::TexCoord, 1)); VertexBuffer *vb1 = new VertexBuffer(NUM * (sizeof(vec3) + sizeof(vec2)); VertexBuffer *vb2 = new VertexBuffer(NUM * sizeof(vec4)); Another problem: the information VertexUsage::Position, 0 is totally useless to the OpenGL/GLSL backend because it does not care about semantics. Once the vertex buffers have been filled with or pointed at data, this is the rendering code: shader->Bind(); shader->SetUniform(u1, GetWorldMatrix()); shader->SetUniform(u2, blah); decl->Bind(); decl->SetStream(vb1, a1, a2); decl->SetStream(vb2, a3); decl->DrawPrimitives(VertexPrimitive::Triangle, NUM / 3); decl->Unbind(); shader->Unbind(); You see that decl is a bit more than just a D3D-like vertex declaration, it kinda takes care of rendering as well. Does this make sense at all? What would be a cleaner design? Or a good source of inspiration?

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• Naming Convention for Dedicated Thread Locking objects

  - by Chris Sinclair

  A relatively minor question, but I haven't been able to find official documentation or even blog opinion/discussions on it. Simply put: when I have a private object whose sole purpose is to serve for private lock, what do I name that object? class MyClass { private object LockingObject = new object(); void DoSomething() { lock(LockingObject) { //do something } } } What should we name LockingObject here? Also consider not just the name of the variable but how it looks in-code when locking. I've seen various examples, but seemingly no solid go-to advice: Plenty of usages of SyncRoot (and variations such as _syncRoot). Code Sample: lock(SyncRoot), lock(_syncRoot) This appears to be influenced by VB's equivalent SyncLock statement, the SyncRoot property that exists on some of the ICollection classes and part of some kind of SyncRoot design pattern (which arguably is a bad idea) Being in a C# context, not sure if I'd want to have a VBish naming. Even worse, in VB naming the variable the same as the keyword. Not sure if this would be a source of confusion or not. thisLock and lockThis from the MSDN articles: C# lock Statement, VB SyncLock Statement Code Sample: lock(thisLock), lock(lockThis) Not sure if these were named minimally purely for the example or not Kind of weird if we're using this within a static class/method. Several usages of PadLock (of varying casing) Code Sample: lock(PadLock), lock(padlock) Not bad, but my only beef is it unsurprisingly invokes the image of a physical "padlock" which I tend to not associate with the abstract threading concept. Naming the lock based on what it's intending to lock Code Sample: lock(messagesLock), lock(DictionaryLock), lock(commandQueueLock) In the VB SyncRoot MSDN page example, it has a simpleMessageList example with a private messagesLock object I don't think it's a good idea to name the lock against the type you're locking around ("DictionaryLock") as that's an implementation detail that may change. I prefer naming around the concept/object you're locking ("messagesLock" or "commandQueueLock") Interestingly, I very rarely see this naming convention for locking objects in code samples online or on StackOverflow. Question: What's your opinion generally about naming private locking objects? Recently, I've started naming them ThreadLock (so kinda like option 3), but I'm finding myself questioning that name. I'm frequently using this locking pattern (in the code sample provided above) throughout my applications so I thought it might make sense to get a more professional opinion/discussion about a solid naming convention for them. Thanks!

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• What is this JavaScript gibberish?

  - by W3Geek

  I am studying how to make a 2D game with JavaScript by reading open source JavaScript games and I came across this gibberish... aSpriteData = [ "}\"¹-º\"À+º\"À+º\"À+º\"¿¤À ~C_ +º\"À+º\"À+º\"À*P7²OK%¾+½u_\"À<¡a¡a¡bM@±@ª", // 0 ground "a ' ![± 7°³b£[mt<Nµ7z]~¨OR»[f_7l},tl},+}%XN²Sb[bl£[±%Y_¹ !@ $", // 1 qbox "!A % @,[] ±}°@;µn¦&X£ <$ §¤ 8}}@Prc'U#Z'H'@· ¶\"is ¤&08@£(", // 2 mario " ´!A.@H#q8¸»e-½n®@±oW:&X¢a<&bbX~# }LWP41}k¬#3¨q#1f RQ@@:4@$", // 3 mario jump " 40 q$!hWa-½n¦#_Y}a©,0#aaPw@=cmY<mq©GBagaq&@q#0§0t0¤ $", // 4 mario run "+hP_@", // 5 pipe left "¢,6< R¤", // 6 pipe right "@ & ,'+hP?>³®'©}[!»¹.¢_^¥y/pX¸#µ°=a¾½hP?>³®'©}[!»¹.¢_^ Ba a", // 7 pipe top left "@ , !] \"º £] , 8O #7a&+¢ §²!cº 9] P &O ,4 e", // 8 pipe top right " £ #! ,! P!!vawd/XO¤8¼'¤P½»¹²'9¨ \"P²Pa²(!¢5!N*(4´b!Gk(a", // 9 goomba " Xu X5 =ou!¯­¬a[Z¼q.°u#|xv ¸··@=~^H'WOJ!¯­¬a=Nu ²J <J a", // 10 coin // yui "@ & !MX ~L \"y %P *¢ 5a K w !L \"y %P *­a%¬¢ 4 a", // 11 ebox // yui "¢ ,\"²+aN!@ &7 }\"²+aN!XH # }\"²+aN!X% 8}\"²+aN!X%£@ (", // 12 bricks "} %¿¢!N° I¨²*<P%.8\"h,!Cg r¥ H³a4X¢*<P%.H#I¬ :a!u !q", // 13 block makeSpace(20) + "4a }@ }0 N( w$ }\" N! +aa", // 14 bush left " r \"²y!L%aN zPN NyN#²L}[/cy¾ N" + makeSpace(18) + "@", // 15 bush mid makeSpace(18) + "++ !R·a!x6 &+6 87L ¢6 P+ 8+ (", // 16 bush right " %©¦ +pq 7> \"³ s" + makeSpace(25) + "@", // 17 cloud bottom left "a/a_#².Q¥'¥b}8.£¨7!X\"K+5cqs%(" + makeSpace(18) + "0", // 18 cloud bottom mid "bP ¢L P+ 8%a,*a%§@ J" + makeSpace(22) + "(", // 19 cloud bottom right "", // 20 mushroom "", // koopa 16x24 "", // 22 star "", // 23 flagpole "", // 24 flag "", // 25 flagpole top " 6 ~ }a }@ }0 }( }$ }\" }! } a} @} 0} (} $} \"² $", // 26 hill slope "a } \"m %8 *P!MF 5la\"y %P" + makeSpace(18) + "(", // 27 hill mid makeSpace(30) + "%\" t!DK \"q", // 28 hill top "", // 29 castle bricks "", // 30 castle doorway bottom "", // 31 castle doorway top "", // 32 castle top "", // 33 castle top 2 "", // 34 castle window right "", // 35 castle window left "", // 36 castle flag makeSpace(19) + "8@# (9F*RSf.8 A¢$!¢040HD", // 37 goomba flat " *(!¬#q³¡[_´Yp~¡=<¥g=&'PaS²¿ Sbq*<I#*£Ld%Ryd%¼½e8H8bf#0a", // 38 mario dead " = ³ #b 'N¶ Z½Z Z½Z Z½Z Z½Z Z½Z Z½Z =[q ²@ ³ ¶ 0", // 39 coin step 1 " ?@ /q /e '¤ #³ !ºa }@ N0 ?( /e '¤ #³ ¿ _a \"", // 40 coin step 2 " / > ] º !² #¢ %a + > ] º !² #¢ 'a \"", // 41 coin step 3 " 7¢ +² *] %> \"p !Ga t¢ I² 4º *] %> \"p ¡ Oa \"" // 42 coin step 4 ], What does it do? If you want to look at the source file here it is: http://www.nihilogic.dk/labs/mario/mario.js Beware, there is more gibberish inside. I can't seem to make sense of any of it. Thank you.

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• How does I/O work for large graph databases?

  - by tjb1982

  I should preface this by saying that I'm mostly a front end web developer, trained as a musician, but over the past few years I've been getting more and more into computer science. So one idea I have as a fun toy project to learn about data structures and C programming was to design and implement my own very simple database that would manage an adjacency list of posts. I don't want SQL (maybe I'll do my own query language? I'm just having fun). It should support ACID. It should be capable of storing 1TB let's say. So with that, I was trying to think of how a database even stores data, without regard to data structures necessarily. I'm working on linux, and I've read that in that world "everything is a file," including hardware (like /dev/*), so I think that that obviously has to apply to a database, too, and it clearly does--whether it's MySQL or PostgreSQL or Neo4j, the database itself is a collection of files you can see in the filesystem. That said, there would come a point in scale where loading the entire database into primary memory just wouldn't work, so it doesn't make sense to design it with that mindset (I assume). However, reading from secondary memory would be much slower and regardless some portion of the database has to be in primary memory in order for you to be able to do anything with it. I read this post: Why use a database instead of just saving your data to disk? And I found it difficult to understand how other databases, like SQLite or Neo4j, read and write from secondary memory and are still very fast (faster, it would seem, than simply writing files to the filesystem as the above question suggests). It seems the key is indexing. But even indexes need to be stored in secondary memory. They are inherently smaller than the database itself, but indexes in a very large database might be prohibitively large, too. So my question is how is I/O generally done with large databases like the one I described above that would be at least 1TB storing a big adjacency list? If indexing is more or less the answer, how exactly does indexing work--what data structures should be involved?

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• Questions re: Eclipse Jobs API

  - by BenCole

  Similar to http://stackoverflow.com/questions/8738160/eclipse-jobs-api-for-a-stand-alone-swing-project This question mentions the Jobs API from the Eclipse IDE: ...The disadvantage of the pre-3.0 approach was that the user had to wait until an operation completed before the UI became responsive again. The UI still provided the user the ability to cancel the currently running operation but no other work could be done until the operation completed. Some operations were performed in the background (resource decoration and JDT file indexing are two such examples) but these operations were restricted in the sense that they could not modify the workspace. If a background operation did try to modify the workspace, the UI thread would be blocked if the user explicitly performed an operation that modified the workspace and, even worse, the user would not be able to cancel the operation. A further complication with concurrency was that the interaction between the independent locking mechanisms of different plug-ins often resulted in deadlock situations. Because of the independent nature of the locks, there was no way for Eclipse to recover from the deadlock, which forced users to kill the application... ...The functionality provided by the workspace locking mechanism can be broken down into the following three aspects: Resource locking to ensure multiple operations did not concurrently modify the same resource Resource change batching to ensure UI stability during an operation Identification of an appropriate time to perform incremental building With the introduction of the Jobs API, these areas have been divided into separate mechanisms and a few additional facilities have been added. The following list summarizes the facilities added. Job class: support for performing operations or other work in the background. ISchedulingRule interface: support for determining which jobs can run concurrently. WorkspaceJob and two IWorkspace#run() methods: support for batching of delta change notifications. Background auto-build: running of incremental build at a time when no other running operations are affecting resources. ILock interface: support for deadlock detection and recovery. Job properties for configuring user feedback for jobs run in the background. The rest of this article provides examples of how to use the above-mentioned facilities... In regards to above API, is this an implementation of a particular design pattern? Which one?

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• SQLAuthority News – Presenting at Great Indian Developer Summit 2012 – SQL Server Misconception and Resolutions

  - by pinaldave

  Earlier during TechEd 2012, I presented a session on SQL Server Misconception and Resolutions. It was a pleasure to present this session with Vinod Kumar during the event. Great Indian Developer Summit is around the corner and I will be presenting there once again with the same topic. We had an excellent response during the last event; the hall was so filled, but there were plenty who were not able to get into the session as there was no place for them to sit or stand inside. Well, here is another chance for all who missed the presentation. New Additions During the last session, we were a two-presenter tag team, and we presented the session in a sense that it would suit two speakers in one stage. But this time, I am the only presenter, so I decided to present this session in a much different way. I will still assume there are two presenters. One of the presenters will be me, of course, and the second person will be YOU! Yes, you read that right – you will be presenting this session with me. If you wonder how, well, you will have to attend the session to figure it out. Talking Points We will be talking about the following topics in the session which we will relate to SQL Server: Moon Landing Napoléon Bonaparte Wall of China Bollywood …and of course, SQL Server itself. I promise that this 45 minute- presentation will be the one of the highlights of the event for you. Goodies I can only promise 20 goodies as of the moment. I might bring more when you meet me there. Session Details Title: SQL Server Misconceptions and Resolution – A Practical Perspective (Add to Calendar) Abstract: “The earth is flat”! – An ancient common misconception, which has been proven incorrect as we progressed in modern times. In this session, we will see various database misconceptions prevailing and their resolutions with the aid of the demos. In this unique session, the audience will be a part of the conversation and resolution. Date and Time: April 17, 2012, 16:55 to 17:40 Location: J. N. Tata Auditorium, National Science Symposium Complex (NSSC), Bangalore, India Add to Calendar Reference : Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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• Overload Avoidance

  - by mikef

  A little under a year ago, Matt Simmons wrote a rather reflective article about his terrifying brush with stress-induced ill health. SysAdmins and DBAs have always been prime victims of work-related stress, but I wonder if that predilection is perhaps getting worse, despite the best efforts of Matt and his trusty side-kick, HR. The constant pressure from share-holders and CFOs to 'streamline' the workforce is partially to blame, but the more recent culprit is technology itself. I can't deny that the rise of technologies like virtualization, PowerCLI, PowerShell, and a host of others has been a tremendous boon. As a result, individual IT professionals are now able to handle more and more tasks and manage increasingly large and complex environments. But, without a doubt, this is a two-edged sword; The reward for competence is invariably more work. Unfortunately, SysAdmins play such a pivotal role in modern business that it's easy to see how they can very quickly become swamped in conflicting demands coming from different directions. However, that doesn't justify the ridiculous hours many are asked (or volunteer) to devote to their work. Admirably though their commitment is, it isn't healthy for them, it sets a dangerous expectation, and eventually something will snap. There are times when everyone needs to step up to the plate outside of 'normal' work hours, but that time isn't all the time. Naturally, with all that lovely technology, you can automate more and more of those tricky tasks to keep on top of the workload, but you are still only human. Clever though you may be, there is a very real limit to how far technology can take you. I'm not suggesting that you avoid these technologies, or deliberately aim for mediocrity; I'm just saying that you need to be more than just technically skilled (and Wesley Nonapeptide riffs on and around this topic in his excellent 'Telepathic Robot Drones' blog post). You need to be able to manage expectations, not just Exchange. Specifically, that means your own expectations of what you are capable of, because those come before everyone else's. After all, how can you keep your work-life balance under control, if you're the one setting the bar way too high? Talking to your manager, or discussing issues with your users, is only going to be productive if you have some facts to work with. "Know Thyself" is the first law of managing work overload, and this is obviously a skill which people develop over time; the fact that veteran Sysadmins exist at all is testament to this. I'd just love to know how you get to that point. Personally, I'm using RescueTime to keep myself honest, but I'm open to recommendations for better methods. Do you track your own time, do you have an intuitive sense of what is possible, or do you just rely on someone else to handle that all for you? Cheers, Michael

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• Simple Mouse Move Event in F# with Winforms

  - by MarkPearl

  This evening I had the pleasure of reading one of ThomasP’s blog posts on first class events. It was an excellent read, and I thought I would make a brief derivative of his post to explore some of the basics. In Thomas’s post he has a form with an ellipse on it that when he clicks on the ellipse it pops up a message box with the button clicked… awesome. Something that got me on the post though was the code similar to the one below… // React to Mouse Move events on the form let evtMessages = frm.MouseMove |> Event.map (fun mi -> mi.Location.ToString()) |> Event.map (sprintf "Hey, you clicked on the ellipse.\nUsing: %s") |> Event.add (MessageBox.Show >> ignore) The MessageBox is a function with a string passed into it. What if I wanted to rather change a mutable value holder instead, how would the syntax go for that? Immediately the thought came to me of anonymous functions. I’ve used them before to do something like this… let HelloPerson personName = "Hello " + personName |> fun(x) -> Console.WriteLine(x) So using the same approach I adapted the event code to instead of showing a Message Box with a string passed in to it, to rather change the forms header. |> Event.map (sprintf "Your mouse position is %s") |> Event.add(fun(x) -> frm.Text <- x) Okay… it looks a bit weird with the –> x <- syntax, but makes sense and works… The next thing I wanted to do was change Thomas’s code sample from having an ellipse, and reacting to the position of the mouse and click, to rather trigger the event whenever the mouse moved. This simple involved removing some filtering code. Finally I wanted the code to work as a FSharp Project without having to run through the F# interactive. To achieve this I just needed to find out how to trigger the window event loop. This can be achieved with the code below… // Program eventloop while frm.Created do Application.DoEvents()   So lets look at the complete code sample… #light open System open System.Drawing open System.Windows.Forms // Create the main form let frm = new Form(ClientSize=Size(600,400)) // React to Mouse Move events on the form let evtMessages = frm.MouseMove |> Event.map (fun mi -> mi.Location.ToString()) |> Event.map (sprintf "Your mouse position is %s") |> Event.add(fun(x) -> frm.Text <- x) // Show the form frm.Show() // Program eventloop while frm.Created do Application.DoEvents()

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• Hype and LINQ

  - by Tony Davis

  "Tired of querying in antiquated SQL?" I blinked in astonishment when I saw this headline on the LinqPad site. Warming to its theme, the site suggests that what we need is to "kiss goodbye to SSMS", and instead use LINQ, a modern query language! Elsewhere, there is an article entitled "Why LINQ beats SQL". The designers of LINQ, along with many DBAs, would, I'm sure, cringe with embarrassment at the suggestion that LINQ and SQL are, in any sense, competitive ways of doing the same thing. In fact what LINQ really is, at last, is an efficient, declarative language for C# and VB programmers to access or manipulate data in objects, local data stores, ORMs, web services, data repositories, and, yes, even relational databases. The fact is that LINQ is essentially declarative programming in a .NET language, and so in many ways encourages developers into a "SQL-like" mindset, even though they are not directly writing SQL. In place of imperative logic and loops, it uses various expressions, operators and declarative logic to build up an "expression tree" describing only what data is required, not the operations to be performed to get it. This expression tree is then parsed by the language compiler, and the result, when used against a relational database, is a SQL string that, while perhaps not always perfect, is often correctly parameterized and certainly no less "optimal" than what is achieved when a developer applies blunt, imperative logic to the SQL language. From a developer standpoint, it is a mistake to consider LINQ simply as a substitute means of querying SQL Server. The strength of LINQ is that that can be used to access any data source, for which a LINQ provider exists. Microsoft supplies built-in providers to access not just SQL Server, but also XML documents, .NET objects, ADO.NET datasets, and Entity Framework elements. LINQ-to-Objects is particularly interesting in that it allows a declarative means to access and manipulate arrays, collections and so on. Furthermore, as Michael Sorens points out in his excellent article on LINQ, there a whole host of third-party LINQ providers, that offers a simple way to get at data in Excel, Google, Flickr and much more, without having to learn a new interface or language. Of course, the need to be generic enough to deal with a range of data sources, from something as mundane as a text file to as esoteric as a relational database, means that LINQ is a compromise and so has inherent limitations. However, it is a powerful and beautifully compact language and one that, at least in its "query syntax" guise, is accessible to developers and DBAs alike. Perhaps there is still hope that LINQ can fulfill Phil Factor's lobster-induced fantasy of a language that will allow us to "treat all data objects, whether Word files, Excel files, XML, relational databases, text files, HTML files, registry files, LDAPs, Outlook and so on, in the same logical way, as linked databases, and extract the metadata, create the entities and relationships in the same way, and use the same SQL syntax to interrogate, create, read, write and update them." Cheers, Tony.

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• Clone an Azure VM using Powershell

  - by jamiet

  In a few months time I will, in association with Technitrain, be running a training course entitled Introduction to SQL Server Data Tools. I am currently working on putting together some hands-on lab material for the course delegates and have decided that in order to save time in asking people to install software during the course I am simply going to prepare a virtual machine (VM) containing all the software and lab material for each delegate to use. Given that I am an MSDN subscriber it makes sense to use Windows Azure to host those VMs given that it will be close to, if not completely, free to do so. What I don’t want to do however is separately build a VM for each delegate, I would much rather build one VM and clone it for each delegate. I’ve spent a bit of time figuring out how to do this using Powershell and in this blog post I am sharing a script that will: Prompt for some information (Azure credentials, Azure subscription name, VM name, username & password, etc…) Create a VM on Azure using that information Prompt you to sysprep the VM and image it (this part can’t be done with Powershell so has to be done manually, a link to instructions is provided in the script output) Create three new VMs based on the image Remove those three VMs Simply download the script and execute it within Powershell, assuming you have an Azure account it should take about 20minutes to execute (spinning up VMs and shutting the down isn’t instantaneous). If you experience any issues please do let me know. There are additional notes below. Hope this is useful! @Jamiet  Notes: Obviously there isn’t a lot of point in creating some new VMs and then instantly deleting them. However, this demo script does provide everything you need should you want to do any of these operations in isolation. The names of the three VMs that get created will be suffixed with 001, 002, 003 but you can edit the script to call them whatever you like. The script doesn’t totally clean up after itself. If you specify a service name & storage account name that don’t already exist then it will create them however it won’t remove them when everything is complete. The created image file will also not be deleted. Removing these items can be done by visiting http://manage.windowsazure.com. When creating the image, ensure you use the correct name (the script output tells you what name to use): Here are some screenshots taken from running the script: When the third and final VM gets removed you are asked to confirm via this dialog: Select ‘Yes’

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• AdventureWorks 2014 Sample Databases Are Now Available

  - by aspiringgeek

    Where in the World is AdventureWorks? Recently, SQL Community feedback from twitter prompted me to look in vain for SQL Server 2014 versions of the AdventureWorks sample databases we’ve all grown to know & love. I searched Codeplex, then used the bing & even the google in an effort to locate them, yet all I could find were samples on different sites highlighting specific technologies, an incomplete collection inconsistent with the experience we users had learned to expect.  I began pinging internally & learned that an update to AdventureWorks wasn’t even on the road map.  Fortunately, SQL Marketing manager Luis Daniel Soto Maldonado (t) lent a sympathetic ear & got the update ball rolling; his direct report Darmodi Komo recently announced the release of the shiny new sample databases for OLTP, DW, Tabular, and Multidimensional models to supplement the extant In-Memory OLTP sample DB.  What Success Looks Like In my correspondence with the team, here’s how I defined success: 1. Sample AdventureWorks DBs hosted on Codeplex showcasing SQL Server 2014’s latest-&-greatest features, including:  In-Memory OLTP (aka Hekaton) Clustered Columnstore Online Operations Resource Governor IO 2. Where it makes sense to do so, consolidate the DBs (e.g., showcasing Columnstore likely involves a separate DW DB) 3. Documentation to support experimenting with these features As Microsoft Senior SDE Bonnie Feinberg (b) stated, “I think it would be great to see an AdventureWorks for SQL 2014.  It would be super helpful for third-party book authors and trainers.  It also provides a common way to share examples in blog posts and forum discussions, for example.”  Exactly.  We’ve established a rich & robust tradition of sample databases on Codeplex.  This is what our community & our customers expect.  The prompt response achieves what we all aim to do, i.e., manifests the Service Design Engineering mantra of “delighting the customer”.  Kudos to Luis’s team in SQL Server Marketing & Kevin Liu’s team in SQL Server Engineering for doing so. Download AdventureWorks 2014 Download your copies of SQL Server 2014 AdventureWorks sample databases here.

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• Accessing Repositories from Domain

  - by Paul T Davies

  Say we have a task logging system, when a task is logged, the user specifies a category and the task defaults to a status of 'Outstanding'. Assume in this instance that Category and Status have to be implemented as entities. Normally I would do this: Application Layer: public class TaskService { //... public void Add(Guid categoryId, string description) { var category = _categoryRepository.GetById(categoryId); var status = _statusRepository.GetById(Constants.Status.OutstandingId); var task = Task.Create(category, status, description); _taskRepository.Save(task); } } Entity: public class Task { //... public static void Create(Category category, Status status, string description) { return new Task { Category = category, Status = status, Description = descrtiption }; } } I do it like this because I am consistently told that entities should not access the repositories, but it would make much more sense to me if I did this: Entity: public class Task { //... public static void Create(Category category, string description) { return new Task { Category = category, Status = _statusRepository.GetById(Constants.Status.OutstandingId), Description = descrtiption }; } } The status repository is dependecy injected anyway, so there is no real dependency, and this feels more to me thike it is the domain that is making thedecision that a task defaults to outstanding. The previous version feels like it is the application layeer making that decision. Any why are repository contracts often in the domain if this should not be a posibility? Here is a more extreme example, here the domain decides urgency: Entity: public class Task { //... public static void Create(Category category, string description) { var task = new Task { Category = category, Status = _statusRepository.GetById(Constants.Status.OutstandingId), Description = descrtiption }; if(someCondition) { if(someValue > anotherValue) { task.Urgency = _urgencyRepository.GetById (Constants.Urgency.UrgentId); } else { task.Urgency = _urgencyRepository.GetById (Constants.Urgency.SemiUrgentId); } } else { task.Urgency = _urgencyRepository.GetById (Constants.Urgency.NotId); } return task; } } There is no way you would want to pass in all possible versions of Urgency, and no way you would want to calculate this business logic in the application layer, so surely this would be the most appropriate way? So is this a valid reason to access repositories from the domain?

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• Which statically typed languages support intersection types for function return values?

  - by stakx

  Initial note: This question got closed after several edits because I lacked the proper terminology to state accurately what I was looking for. Sam Tobin-Hochstadt then posted a comment which made me recognise exactly what that was: programming languages that support intersection types for function return values. Now that the question has been re-opened, I've decided to improve it by rewriting it in a (hopefully) more precise manner. Therefore, some answers and comments below might no longer make sense because they refer to previous edits. (Please see the question's edit history in such cases.) Are there any popular statically & strongly typed programming languages (such as Haskell, generic Java, C#, F#, etc.) that support intersection types for function return values? If so, which, and how? (If I'm honest, I would really love to see someone demonstrate a way how to express intersection types in a mainstream language such as C# or Java.) I'll give a quick example of what intersection types might look like, using some pseudocode similar to C#: interface IX { … } interface IY { … } interface IB { … } class A : IX, IY { … } class B : IX, IY, IB { … } T fn() where T : IX, IY { return … ? new A() : new B(); } That is, the function fn returns an instance of some type T, of which the caller knows only that it implements interfaces IX and IY. (That is, unlike with generics, the caller doesn't get to choose the concrete type of T — the function does. From this I would suppose that T is in fact not a universal type, but an existential type.) P.S.: I'm aware that one could simply define a interface IXY : IX, IY and change the return type of fn to IXY. However, that is not really the same thing, because often you cannot bolt on an additional interface IXY to a previously defined type A which only implements IX and IY separately. Footnote: Some resources about intersection types: Wikipedia article for "Type system" has a subsection about intersection types. Report by Benjamin C. Pierce (1991), "Programming With Intersection Types, Union Types, and Polymorphism" David P. Cunningham (2005), "Intersection types in practice", which contains a case study about the Forsythe language, which is mentioned in the Wikipedia article. A Stack Overflow question, "Union types and intersection types" which got several good answers, among them this one which gives a pseudocode example of intersection types similar to mine above.

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• TDD vs. Productivity

  - by Nairou

  In my current project (a game, in C++), I decided that I would use Test Driven Development 100% during development. In terms of code quality, this has been great. My code has never been so well designed or so bug-free. I don't cringe when viewing code I wrote a year ago at the start of the project, and I have gained a much better sense for how to structure things, not only to be more easily testable, but to be simpler to implement and use. However... it has been a year since I started the project. Granted, I can only work on it in my spare time, but TDD is still slowing me down considerably compared to what I'm used to. I read that the slower development speed gets better over time, and I definitely do think up tests a lot more easily than I used to, but I've been at it for a year now and I'm still working at a snail's pace. Each time I think about the next step that needs work, I have to stop every time and think about how I would write a test for it, to allow me to write the actual code. I'll sometimes get stuck for hours, knowing exactly what code I want to write, but not knowing how to break it down finely enough to fully cover it with tests. Other times, I'll quickly think up a dozen tests, and spend an hour writing tests to cover a tiny piece of real code that would have otherwise taken a few minutes to write. Or, after finishing the 50th test to cover a particular entity in the game and all aspects of it's creation and usage, I look at my to-do list and see the next entity to be coded, and cringe in horror at the thought of writing another 50 similar tests to get it implemented. It's gotten to the point that, looking over the progress of the last year, I'm considering abandoning TDD for the sake of "getting the damn project finished". However, giving up the code quality that came with it is not something I'm looking forward to. I'm afraid that if I stop writing tests, then I'll slip out of the habit of making the code so modular and testable. Am I perhaps doing something wrong to still be so slow at this? Are there alternatives that speed up productivity without completely losing the benefits? TAD? Less test coverage? How do other people survive TDD without killing all productivity and motivation?

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