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  • What are the consequences of immutable classes with references to mutable classes?

    - by glenviewjeff
    I've recently begun adopting the best practice of designing my classes to be immutable per Effective Java [Bloch2008]. I have a series of interrelated questions about degrees of mutability and their consequences. I have run into situations where a (Java) class I implemented is only "internally immutable" because it uses references to other mutable classes. In this case, the class under development appears from the external environment to have state. Do any of the benefits (see below) of immutable classes hold true even by only "internally immutable" classes? Is there an accepted term for the aforementioned "internal mutability"? Wikipedia's immutable object page uses the unsourced term "deep immutability" to describe an object whose references are also immutable. Is the distinction between mutability and side-effect-ness/state important? Josh Bloch lists the following benefits of immutable classes: are simple to construct, test, and use are automatically thread-safe and have no synchronization issues do not need a copy constructor do not need an implementation of clone allow hashCode to use lazy initialization, and to cache its return value do not need to be copied defensively when used as a field make good Map keys and Set elements (these objects must not change state while in the collection) have their class invariant established once upon construction, and it never needs to be checked again always have "failure atomicity" (a term used by Joshua Bloch) : if an immutable object throws an exception, it's never left in an undesirable or indeterminate state

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  • Designing a Database Application with OOP

    - by Tim C
    I often develop SQL database applications using Linq, and my methodology is to build model classes to represent each table, and each table that needs inserting or updating gets a Save() method (which either does an InsertOnSubmit() or SubmitChanges(), depending on the state of the object). Often, when I need to represent a collection of records, I'll create a class that inherits from a List-like object of the atomic class. ex. public class CustomerCollection : CoreCollection<Customer> { } Recently, I was working on an application where end-users were experiencing slowness, where each of the objects needed to be saved to the database if they met a certain criteria. My Save() method was slow, presumably because I was making all kinds of round-trips to the server, and calling DataContext.SubmitChanges() after each atomic save. So, the code might have looked something like this foreach(Customer c in customerCollection) { if(c.ShouldSave()) { c.Save(); } } I worked through multiple strategies to optimize, but ultimately settled on passing a big string of data to a SQL stored procedure, where the string has all the data that represents the records I was working with - it might look something like this: CustomerID:34567;CurrentAddress:23 3rd St;CustomerID:23456;CurrentAddress:123 4th St So, SQL server parses the string, performs the logic to determine appropriateness of save, and then Inserts, Updates, or Ignores. With C#/Linq doing this work, it saved 5-10 records / s. When SQL does it, I get 100 records / s, so there is no denying the Stored Proc is more efficient; however, I hate the solution because it doesn't seem nearly as clean or safe. My real concern is that I don't have any better solutions that hold a candle to the performance of the stored proc solution. Am I doing something obviously wrong in how I'm thinking about designing database applications? Are there better ways of designing database applications?

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  • Windows Azure ASP.NET MVC 2 Role with Silverlight

    - by GeekAgilistMercenary
    I was working through some scenarios recently with Azure and Silverlight.  I immediately decided a quick walk through for setting up a Silverlight Application running in an ASP.NET MVC 2 Application would be a cool project. This walk through I have Visual Studio 2010, Silverlight 4, and the Azure SDK all installed.  If you need to download any of those go get em? now. Launch Visual Studio 2010 and start a new project.  Click on the section for cloud templates as shown below. After you name the project, the dialog for what type of Windows Azure Cloud Service Role will display.  I selected ASP.NET MVC 2 Web Role, which adds the MvcWebRole1 Project to the Cloud Service Solution. Since I selected the ASP.NET MVC 2 Project type, it immediately prompts for a unit test project.  Because I just want to get everything running first, I will probably be unit testing the Silverlight and just using the MVC Project as a host for the Silverlight for now, and because I would prefer to just add the unit test project later, I am going to select no here. Once you've created the ASP.NET MVC 2 project to host the Silverlight, then create another new project.  Select the Silverlight section under the Installed Templates in the Add New Project dialog.  Then select Silverlight Application. The next dialog that comes up will inquire about using the existing ASP.NET MVC Application I just created, which I do want it to use that so I leave it checked.  The options section however I do not want to check RIA Web Services, do not want a test page added to the project, and I want Silverlight debugging enabled so I leave that checked.  Once those options are appropriately set, just click on OK and the Silverlight Project will be added to the overall solution. The next steps now are to get the Silverlight object appropriately embedded in the web page.  First open up the Site.Master file in the ASP.NET MVC 2 Project located under the Veiws/Shared/ location.  After you open the file review the content of the <header></header> section.  In that section add another <contentplaceholder></contentplaceholder> tag as shown in the code snippet below. <head runat="server"> <title> <asp:ContentPlaceHolder ID="TitleContent" runat="server" /> </title> <link href="../../Content/Site.css" rel="stylesheet" type="text/css" /> <asp:ContentPlaceHolder ID="HeaderContent" runat="server" /> </head> I usually put it toward the bottom of the header section.  It just seems the <title></title> should be on the top of the section and I like to keep it that way. Now open up the Index.aspx page under the ASP.NET MVC 2 Project located in the Views/Home/ directory.  When you open up that file add a <asp:Content><asp:Content> tag as shown in the next snippet. <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Home Page </asp:Content>   <asp:Content ID=headerContent ContentPlaceHolderID=HeaderContent runat=server>   </asp:Content>   <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2><%= Html.Encode(ViewData["Message"]) %></h2> <p> To learn more about ASP.NET MVC visit <a href="http://asp.net/mvc" title="ASP.NET MVC Website">http://asp.net/mvc</a>. </p> </asp:Content> In that center tag, I am now going to add what is needed to appropriately embed the Silverlight object into the page.  The first thing I needed is a reference to the Silverlight.js file. <script type="text/javascript" src="Silverlight.js"></script> After that comes a bit of nitty gritty Javascript.  I create another tag (and for those in the know, this is exactly like the generated code that is dumped into the *.html page generated with any Silverlight Project if you select to "add a test page that references the application".  The complete Javascript is below. function onSilverlightError(sender, args) { var appSource = ""; if (sender != null && sender != 0) { appSource = sender.getHost().Source; }   var errorType = args.ErrorType; var iErrorCode = args.ErrorCode;   if (errorType == "ImageError" || errorType == "MediaError") { return; }   var errMsg = "Unhandled Error in Silverlight Application " + appSource + "\n";   errMsg += "Code: " + iErrorCode + " \n"; errMsg += "Category: " + errorType + " \n"; errMsg += "Message: " + args.ErrorMessage + " \n";   if (errorType == "ParserError") { errMsg += "File: " + args.xamlFile + " \n"; errMsg += "Line: " + args.lineNumber + " \n"; errMsg += "Position: " + args.charPosition + " \n"; } else if (errorType == "RuntimeError") { if (args.lineNumber != 0) { errMsg += "Line: " + args.lineNumber + " \n"; errMsg += "Position: " + args.charPosition + " \n"; } errMsg += "MethodName: " + args.methodName + " \n"; }   throw new Error(errMsg); } I literally, since it seems to work fine, just use what is populated in the automatically generated page.  After getting the appropriate Javascript into place I put the actual Silverlight Object Embed code into the HTML itself.  Just so I know the positioning and for final verification when running the application I insert the embed code just below the Index.aspx page message.  As shown below. <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2> <%= Html.Encode(ViewData["Message"]) %></h2> <p> To learn more about ASP.NET MVC visit <a href="http://asp.net/mvc" title="ASP.NET MVC Website"> http://asp.net/mvc</a>. </p> <div id="silverlightControlHost"> <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"> <param name="source" value="ClientBin/CloudySilverlight.xap" /> <param name="onError" value="onSilverlightError" /> <param name="background" value="white" /> <param name="minRuntimeVersion" value="4.0.50401.0" /> <param name="autoUpgrade" value="true" /> <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50401.0" style="text-decoration: none"> <img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style: none" /> </a> </object> <iframe id="_sl_historyFrame" style="visibility: hidden; height: 0px; width: 0px; border: 0px"></iframe> </div> </asp:Content> I then open up the Silverlight Project MainPage.xaml.  Just to make it visibly obvious that the Silverlight Application is running in the page, I added a button as shown below. <UserControl x:Class="CloudySilverlight.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400">   <Grid x:Name="LayoutRoot" Background="White"> <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="48,40,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" /> </Grid> </UserControl> Just for kicks, I added a message box that would popup, just to show executing functionality also. private void button1_Click(object sender, RoutedEventArgs e) { MessageBox.Show("It runs in the cloud!"); } I then executed the ASP.NET MVC 2 and could see the Silverlight Application in page.  With a quick click of the button, I got a message box.  Success! Now the next step is getting the ASP.NET MVC 2 Project and Silverlight published to the cloud.  As of Visual Studio 2010, Silverlight 4, and the latest Azure SDK, this is actually a ridiculously easy process. Navigate to the Azure Cloud Services web site. Once that is open go back in Visual Studio and right click on the cloud project and select publish. This will publish two files into a directory.  Copy that directory so you can easily paste it into the Azure Cloud Services web site.  You'll have to click on the application role in the cloud (I will have another blog entry soon about where, how, and best practices in the cloud). In the text boxes shown, select the application package file and the configuration file and place them in the appropriate text boxes.  This is the part were it comes in handy to have copied the directory path of the file location.  That way when you click on browser you can just paste that in, then hit enter.  The two files will be listed and you can select the appropriate file. Once that is done, name the service deployment.  Then click on publish.  After a minute or so you will see the following screen. Now click on run.  Once the MvcWebRole1 goes green (the little light symbol to the left of the status) click on the Web Site URL.  Be patient during this process too, it could take a minute or two.  The Silverlight application should again come up just like you ran it on your local machine. Once staging is up and running, click on the circular icon with two arrows to move staging to production.  Once you are done make sure the green light is again go for the production deploy, then click on the Web Site URL to verify the site is working.  At this point I had a successful development, staging, and production deployment. Thanks for reading, hope this was helpful.  I have more Windows Azure and other cloud related material coming, so stay tuned. Original Entry

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  • Scheduled Deprecation of Legacy Obligation Features

    - by Wes Curtis
    The Obligation object in ETPM includes some functionality and tables that, to our knowledge, are not being used by customers and implementers are this time.  Removing this logic and the related tables should benefit the performance of and simplify logic executed during Obligation maintenance processing. The Release Notes included with ETPM v2.3.1 announced that the product plans to deprecate the functionality on Obligation for Contract Terms, Contract Quantities, Tax Exemptions, Terms & Conditions and Obligation Type Start Options.  Our plan is to remove this functionality in the next release of ETPM. We have already confirmed with most project teams that these features are not being used so the deprecation should have no impact on existing designs or process. If you think your project may be impacted by this deprecation, please review any Business Object that has been created for the Obligation maintenance object to make sure that no elements are being defined for any of the following child tables: -          CI_SA_CONTERM -          CI_SA_CONT_QTY -          CI_TOU_CONT_VAL -          CI_SA_TC   As part of this deprecation, the following administrative tables are being removed along with their related metadata: -          Contract Quantity Type -          Tax Exempt Type -          Terms and Conditions Please contact myself or the Oracle Tax Product Management team if your implementation has actually used these objects in their designs. We can discuss options to mitigate impacts of this planned deprecation.  We will continue to announce planned deprecations in the Release Notes for each release and will contact project teams ahead of time to confirm that these deprecations will have little to no impact on our customers.

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  • C# - How to store and reuse queries

    - by Jason Holland
    I'm learning C# by programming a real monstrosity of an application for personal use. Part of my application uses several SPARQL queries like so: const string ArtistByRdfsLabel = @" PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT DISTINCT ?artist WHERE {{ {{ ?artist rdf:type <http://dbpedia.org/ontology/MusicalArtist> . ?artist rdfs:label ?rdfsLabel . }} UNION {{ ?artist rdf:type <http://dbpedia.org/ontology/Band> . ?artist rdfs:label ?rdfsLabel . }} FILTER ( str(?rdfsLabel) = '{0}' ) }}"; string Query = String.Format(ArtistByRdfsLabel, Artist); I don't like the idea of keeping all these queries in the same class that I'm using them in so I thought I would just move them into their own dedicated class to remove clutter in my RestClient class. I'm used to working with SQL Server and just wrapping every query in a stored procedure but since this is not SQL Server I'm scratching my head on what would be the best for these SPARQL queries. Are there any better approaches to storing these queries using any special C# language features (or general, non C# specific, approaches) that I may not already know about?

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  • How to create per-vertex normals when reusing vertex data?

    - by Chris Smith
    I am displaying a cube using a vertex buffer object (gl.ELEMENT_ARRAY_BUFFER). This allows me to specify vertex indicies, rather than having duplicate vertexes. In the case of displaying a simple cube, this means I only need to have eight vertices total. Opposed to needing three vertices per triangle, times two triangles per face, times six faces. Sound correct so far? My question is, how do I now deal with vertex attribute data such as color, texture coordinates, and normals when reusing vertices using the vertex buffer object? If I am reusing the same vertex data in my indexed vertex buffer, how can I differentiate when vertex X is used as part of the cube's front face versus the cube's left face? In both cases I would like the surface normal and texture coordinates to be different. I understand I could average the surface normal, however I would like to render a cube. Also, this still doesn't work for texture coordinates. Is there a way to save memory using a vertex buffer object while being able to provide different vertex attribute data based on context? (Per-triangle would be idea.) Or should I just duplicate each vertex for each context in which it gets rendered. (So there is a one-to-one mapping between vertex, normal, color, etc.) Note: I'm using OpenGL ES.

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  • Ubuntu and bumblebee and intel problem

    - by LnxSlck
    I have a brain teaser that i can't solve. When 12.04 (64bits) came out, i did a fresh install and then installed bumblebee with: sudo add-apt-repository ppa:bumblebee/stable sudo apt-get install bumblebee bumblebee-nvidia And Ubuntu recognized (System Settings - Details) Intel Card for primary card, and i could launch applications with optirun. I have: 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 01:00.0 VGA compatible controller: NVIDIA Corporation GF119 [GeForce GT 520MX] (rev ff) Now, a few days back, i did the exact same thing, installed from the same DVD everything the same, installed bumblebee the same way. Nvidia with Optirun works fine, but Ubuntu doesn't have 3D effects: root@deathstar:~# optirun /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce GT 520MX/PCIe/SSE2 OpenGL version string: 4.2.0 NVIDIA 295.40 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: no GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no I never did anything to install Intel drivers (except installing mesa-utils), before bumblebee got everything working, but now i can't get Ubuntu to get Unity with 3D. Can someone help me please get Unity 3d working? Your help will be much appreciated

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  • How does flocking algorithm work?

    - by Chan
    I read and understand the basic of flocking algorithm. Basically, we need to have 3 behaviors: 1. Cohesion 2. Separation 3. Alignment From my understanding, it's like a state machine. Every time we do an update (then draw), we check all the constraints on both three behaviors. And each behavior returns a Vector3 which is the "correct" orientation that an object should transform to. So my initial idea was /// <summary> /// Objects stick together /// </summary> /// <returns></returns> private Vector3 Cohesion() { Vector3 result = new Vector3(0.0f, 0.0f, 0.0f); return result; } /// <summary> /// Object align /// </summary> /// <returns></returns> private Vector3 Align() { Vector3 result = new Vector3(0.0f, 0.0f, 0.0f); return result; } /// <summary> /// Object separates from each others /// </summary> /// <returns></returns> private Vector3 Separate() { Vector3 result = new Vector3(0.0f, 0.0f, 0.0f); return result; } Then I search online for pseudocode but many of them involve velocity and acceleration plus other stuffs. This part confused me. In my game, all objects move at constant speed, and they have one leader. So can anyone share me an idea how to start on implement this flocking algorithm? Also, did I understand it correctly? (I'm using XNA 4.0)

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  • Executing Components in an Entity Component System

    - by John
    Ok so I am just starting to grasp the whole ECS paradigm right now and I need clarification on a few things. For the record, I am trying to develop a game using C++ and OpenGL and I'm relatively new to game programming. First of all, lets say I have an Entity class which may have several components such as a MeshRenderer,Collider etc. From what I have read, I understand that each "system" carries out a specific task such as calculating physics and rendering and may use more that one component if needed. So for example, I would have a MeshRendererSystem act on all entities with a MeshRenderer component. Looking at Unity, I see that each Gameobject has, by default, got components such as a renderer, camera, collider and rigidbody etc. From what I understand, an entity should start out as an empty "container" and should be filled with components to create a certain type of game object. So what I dont understand is how the "system" works in an entity component system. http://docs.unity3d.com/ScriptReference/GameObject.html So I have a GameObject(The Entity) class like class GameObject { public: GameObject(std::string objectName); ~GameObject(void); Component AddComponent(std::string name); Component AddComponent(Component componentType); }; So if I had a GameObject to model a warship and I wanted to add a MeshRenderer component, I would do the following: warship->AddComponent(new MeshRenderer()); In the MeshRenderers constructor, should I call on the MeshRendererSystem and "subscribe" the warship object to this system? In that case, the MeshRendererSystem should probably be a Singleton("shudder"). From looking at unity's GameObject, if each object potentially has a renderer or any of the components in the default GameObject class, then Unity would iterate over all objects available. To me, this seems kind of unnecessary since some objects might not need to be rendered for example. How, in practice, should these systems be implemented?

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  • Android-Libgdx-ProGuard: Usefulness without DexGuard? [on hold]

    - by Rico Pablo Mince
    So I'm developing a game for Android - using LibGDX - and noticed that the Android SDK (HDK, MDK, WhatTheHellEvarDK) has ProGuard built-in. Browsing the ProGuard page is like searching Google: you get that the idea is to sell some product (in this case, it's DexGuard). That leaves me wondering what features are left out of ProGuard that a game developer targeting Android should worry about. For instance, the ProGuard FAQs answer the question: "Does ProGuard encrypt string constants?" by saying: "No. String encryption in program code has to be perfectly reversible by definition, so it only improves the obfuscation level. It increases the footprint of the code. However, by popular demand, ProGuard's closed-source sibling for Android, DexGuard, does provide string encryption, along with more protection techniques against static and dynamic analysis." Alright. OK. But isn't "...improves the obfuscation level" EXACTLY what ProGuard is supposed to do? Are there better options that can be implemented at build-time in Eclipse using the Gradle options and Libgdx? In particular, the assets folder and res-specific folders will need some protection. The code itself doesn't cure cancer, but I'd prefer if nobody could copy/paste it with different game art and call it "IhAxEdUrGamE"....

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  • Autocomplete in Silverlight with Visual Studio 2010

    - by Sayre Collado
    Last week I keep searching on how to use the autocomplete in silverligth with visual studio 2010 but most of the examples that I find they are using a textbox or combobox for the autocomplete. I tried to study those examples and apply to the single autocomplete from tools on my silverlight project. And now this is the result. I will use a database again from my previous post (Silverlight Simple DataBinding in DataGrid) to show how the autocomplete works with database. This is the output: First, this is the setup for my autocomplete: //The tags for autocompletebox on XAML Second, my simple snippets: //Event for the autocomplete to send a text string to my function private void autoCompleteBox1_KeyUp(object sender, KeyEventArgs e) { autoCompleteBox1.Populating += (s, args) => { args.Cancel = true; var c = new Service1Client(); c.GetListByNameCompleted +=new EventHandler(c_GetListByNameCompleted); c.GetListByNameAsync(autoCompleteBox1.Text); }; } //Getting result from database void c_GetListByNameCompleted(object sender, GetListByNameCompletedEventArgs e) { autoCompleteBox1.ItemsSource = e.Result; autoCompleteBox1.PopulateComplete(); } The snippets above will show on how to use the autocompleteBox using the data from database that bind in DataGrid. But what if we want to show the result on DataGrid while the autocomplete changing the items source? Ok just add one line to c_GetListByNameCompleted void c_GetListByNameCompleted(object sender, GetListByNameCompletedEventArgs e) { autoCompleteBox1.ItemsSource = e.Result; autoCompleteBox1.PopulateComplete(); dataGrid1.ItemsSource = e.Result; }

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  • Is it just me or is this a baffling tech interview question

    - by Matthew Patrick Cashatt
    Background I was just asked in a tech interview to write an algorithm to traverse an "object" (notice the quotes) where A is equal to B and B is equal to C and A is equal to C. That's it. That is all the information I was given. I asked the interviewer what the goal was but apparently there wasn't one, just "traverse" the "object". I don't know about anyone else, but this seems like a silly question to me. I asked again, "am I searching for a value?". Nope. Just "traverse" it. Why would I ever want to endlessly loop through this "object"?? To melt my processor maybe?? The answer according to the interviewer was that I should have written a recursive function. OK, so why not simply ask me to write a recursive function? And who would write a recursive function that never ends? My question: Is this a valid question to the rest of you and, if so, can you provide a hint as to what I might be missing? Perhaps I am thinking too hard about solving real world problems. I have been successfully coding for a long time but this tech interview process makes me feel like I don't know anything. Final Answer: CLOWN TRAVERSAL!!! (See @Matt's answer below) Thanks! Matt

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  • array and array_view from amp.h

    - by Daniel Moth
    This is a very long post, but it also covers what are probably the classes (well, array_view at least) that you will use the most with C++ AMP, so I hope you enjoy it! Overview The concurrency::array and concurrency::array_view template classes represent multi-dimensional data of type T, of N dimensions, specified at compile time (and you can later access the number of dimensions via the rank property). If N is not specified, it is assumed that it is 1 (i.e. single-dimensional case). They are rectangular (not jagged). The difference between them is that array is a container of data, whereas array_view is a wrapper of a container of data. So in that respect, array behaves like an STL container, whereas the closest thing an array_view behaves like is an STL iterator (albeit with random access and allowing you to view more than one element at a time!). The data in the array (whether provided at creation time or added later) resides on an accelerator (which is specified at creation time either explicitly by the developer, or set to the default accelerator at creation time by the runtime) and is laid out contiguously in memory. The data provided to the array_view is not stored by/in the array_view, because the array_view is simply a view over the real source (which can reside on the CPU or other accelerator). The underlying data is copied on demand to wherever the array_view is accessed. Elements which differ by one in the least significant dimension of the array_view are adjacent in memory. array objects must be captured by reference into the lambda you pass to the parallel_for_each call, whereas array_view objects must be captured by value (into the lambda you pass to the parallel_for_each call). Creating array and array_view objects and relevant properties You can create array_view objects from other array_view objects of the same rank and element type (shallow copy, also possible via assignment operator) so they point to the same underlying data, and you can also create array_view objects over array objects of the same rank and element type e.g.   array_view<int,3> a(b); // b can be another array or array_view of ints with rank=3 Note: Unlike the constructors above which can be called anywhere, the ones in the rest of this section can only be called from CPU code. You can create array objects from other array objects of the same rank and element type (copy and move constructors) and from other array_view objects, e.g.   array<float,2> a(b); // b can be another array or array_view of floats with rank=2 To create an array from scratch, you need to at least specify an extent object, e.g. array<int,3> a(myExtent);. Note that instead of an explicit extent object, there are convenience overloads when N<=3 so you can specify 1-, 2-, 3- integers (dependent on the array's rank) and thus have the extent created for you under the covers. At any point, you can access the array's extent thought the extent property. The exact same thing applies to array_view (extent as constructor parameters, incl. convenience overloads, and property). While passing only an extent object to create an array is enough (it means that the array will be written to later), it is not enough for the array_view case which must always wrap over some other container (on which it relies for storage space and actual content). So in addition to the extent object (that describes the shape you'd like to be viewing/accessing that data through), to create an array_view from another container (e.g. std::vector) you must pass in the container itself (which must expose .data() and a .size() methods, e.g. like std::array does), e.g.   array_view<int,2> aaa(myExtent, myContainerOfInts); Similarly, you can create an array_view from a raw pointer of data plus an extent object. Back to the array case, to optionally initialize the array with data, you can pass an iterator pointing to the start (and optionally one pointing to the end of the source container) e.g.   array<double,1> a(5, myVector.begin(), myVector.end()); We saw that arrays are bound to an accelerator at creation time, so in case you don’t want the C++ AMP runtime to assign the array to the default accelerator, all array constructors have overloads that let you pass an accelerator_view object, which you can later access via the accelerator_view property. Note that at the point of initializing an array with data, a synchronous copy of the data takes place to the accelerator, and then to copy any data back we'll see that an explicit copy call is required. This does not happen with the array_view where copying is on demand... refresh and synchronize on array_view Note that in the previous section on constructors, unlike the array case, there was no overload that accepted an accelerator_view for array_view. That is because the array_view is simply a wrapper, so the allocation of the data has already taken place before you created the array_view. When you capture an array_view variable in your call to parallel_for_each, the copy of data between the non-CPU accelerator and the CPU takes place on demand (i.e. it is implicit, versus the explicit copy that has to happen with the array). There are some subtleties to the on-demand-copying that we cover next. The assumption when using an array_view is that you will continue to access the data through the array_view, and not through the original underlying source, e.g. the pointer to the data that you passed to the array_view's constructor. So if you modify the data through the array_view on the GPU, the original pointer on the CPU will not "know" that, unless one of two things happen: you access the data through the array_view on the CPU side, i.e. using indexing that we cover below you explicitly call the array_view's synchronize method on the CPU (this also gets called in the array_view's destructor for you) Conversely, if you make a change to the underlying data through the original source (e.g. the pointer), the array_view will not "know" about those changes, unless you call its refresh method. Finally, note that if you create an array_view of const T, then the data is copied to the accelerator on demand, but it does not get copied back, e.g.   array_view<const double, 5> myArrView(…); // myArrView will not get copied back from GPU There is also a similar mechanism to achieve the reverse, i.e. not to copy the data of an array_view to the GPU. copy_to, data, and global copy/copy_async functions Both array and array_view expose two copy_to overloads that allow copying them to another array, or to another array_view, and these operations can also be achieved with assignment (via the = operator overloads). Also both array and array_view expose a data method, to get a raw pointer to the underlying data of the array or array_view, e.g. float* f = myArr.data();. Note that for array_view, this only works when the rank is equal to 1, due to the data only being contiguous in one dimension as covered in the overview section. Finally, there are a bunch of global concurrency::copy functions returning void (and corresponding concurrency::copy_async functions returning a future) that allow copying between arrays and array_views and iterators etc. Just browse intellisense or amp.h directly for the full set. Note that for array, all copying described throughout this post is deep copying, as per other STL container expectations. You can never have two arrays point to the same data. indexing into array and array_view plus projection Reading or writing data elements of an array is only legal when the code executes on the same accelerator as where the array was bound to. In the array_view case, you can read/write on any accelerator, not just the one where the original data resides, and the data gets copied for you on demand. In both cases, the way you read and write individual elements is via indexing as described next. To access (or set the value of) an element, you can index into it by passing it an index object via the subscript operator. Furthermore, if the rank is 3 or less, you can use the function ( ) operator to pass integer values instead of having to use an index object. e.g. array<float,2> arr(someExtent, someIterator); //or array_view<float,2> arr(someExtent, someContainer); index<2> idx(5,4); float f1 = arr[idx]; float f2 = arr(5,4); //f2 ==f1 //and the reverse for assigning, e.g. arr(idx[0], 7) = 6.9; Note that for both array and array_view, regardless of rank, you can also pass a single integer to the subscript operator which results in a projection of the data, and (for both array and array_view) you get back an array_view of rank N-1 (or if the rank was 1, you get back just the element at that location). Not Covered In this already very long post, I am not going to cover three very cool methods (and related overloads) that both array and array_view expose: view_as, section, reinterpret_as. We'll revisit those at some point in the future, probably on the team blog. Comments about this post by Daniel Moth welcome at the original blog.

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  • How can I separate the user interface from the business logic while still maintaining efficiency?

    - by Uri
    Let's say that I want to show a form that represents 10 different objects on a combobox. For example, I want the user to pick one hamburguer from 10 different ones that contain tomatoes. Since I want to separate UI and logic, I'd have to pass the form a string representation of the hamburguers in order to display them on the combobox. Otherwise, the UI would have to dig into the objects fields. Then the user would pick a hamburguer from the combobox, and submit it back to the controller. Now the controller would have to find again said hamburguer based on the string representation used by the form (maybe an ID?). Isn't that incredibly inefficient? You already had the objects you wanted to pick one from. If you submited to the form the whole objects, and then returned a specific object, you wouldn't have to refind it later on since the form already returned a reference to that object. Moreover, if I'm wrong and you actually should send the whole object to the form, how can I isolate UI from logic?

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  • Deferred rendering with both Clockwise and CounterClockwise culling

    - by user1423893
    I have a deferred rendering system that works well with objects that appear solid and drawn using CounterClockwise culling. I have a problem with Clockwise culled objects that are supposed to represent hollow that display their inside faces only. The image below shows a CounterClockwise culled object (left) Clockwise culled object (right). The Clockwise culled object faces display what would be displayed on the CounterClockwise face. How can I get the lighting to light the inner faces for Clockwise culled objects and continue lighting the outer CounterClockwise faces as normal? My lighting method is below private void DeferredLighting(GameTime gameTime) { // Set the render target for the lights game.GraphicsDevice.SetRenderTarget(lightMap); // Clear the render target to (0, 0, 0, 0) game.GraphicsDevice.Clear(Color.Transparent); // Set the render states game.GraphicsDevice.BlendState = BlendState.Additive; game.GraphicsDevice.DepthStencilState = DepthStencilState.None; game.GraphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise; // Set sampler state to Point as the Surface type requires it in XNA 4.0 game.GraphicsDevice.SamplerStates[0] = SamplerState.PointClamp; // Set the camera properties for all lights BaseLight.SetCameraProperties(game.ActiveCamera); // Draw the lights int numLights = lights.Count; for (int i = 0; i < numLights; ++i) { if (lights[i].Diffuse.W > 0f) { lights[i].Render(gameTime, ref normalMap, ref depthMap, ref sgrMap); } } // Resolve the render target game.GraphicsDevice.SetRenderTarget(null); } I have tried adjusting the render states but no combination works for both objects.

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  • Organising data access for dependency injection

    - by IanAWP
    In our company we have a relatively long history of database backed applications, but have only just begun experimenting with dependency injection. I am looking for advice about how to convert our existing data access pattern into one more suited for dependency injection. Some specific questions: Do you create one access object per table (Given that a table represents an entity collection)? One interface per table? All of these would need the low level Data Access object to be injected, right? What about if there are dozens of tables, wouldn't that make the composition root into a nightmare? Would you instead have a single interface that defines things like GetCustomer(), GetOrder(), etc? If I took the example of EntityFramework, then I would have one Container that exposes an object for each table, but that container doesn't conform to any interface itself, so doesn't seem like it's compatible with DI. What we do now, in case it helps: The way we normally manage data access is through a generic data layer which exposes CRUD/Transaction capabilities and has provider specific subclasses which handle the creation of IDbConnection, IDbCommand, etc. Actual table access uses Table classes that perform the CRUD operations associated with a particular table and accept/return domain objects that the rest of the system deals with. These table classes expose only static methods, and utilise a static DataAccess singleton instantiated from a config file.

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  • Mailbox move issue from Exchange 2003 to Exchange 2010

    - by Ryan Roussel
    Today while moving mailboxes between Exchange 2003 and Exchange 2010, I hit an issue with a couple of mailboxes.  These mailboxes all popped access denied errors or more exactly: Insufficient Access Rights to perform the operation.   The cause was similar to the mail flow issue in that inheritable permissions were not turned on for the user object in Active Directory.  This also presented it’s own unique problem in that since the initial move request failed because of permissions, it had to be cleared before a new move request could be created. On top of that, the request did not show up in the EMC.  I used the following process to clear the request, assign permission, then create a new request:   1. First you need to know the ExchangeGUID of the mailbox for the remove-moverequest command.  To quickly get the GUID for a mailbox simply run:         2. Next we need to clear out the move request using PowerShell by running: [PS] c:\>Remove-moverequest -moverequestqueue "mailbox database 1030639620" -mailboxguid 8525686f-d4d3-42b7-92f1-46d77ea841a3   3. Then to re-establish inheritable permissions. This can be done by using AD Users and Computers, switching to View Advanced Features, then under the Security tab of the object.  Click Advanced, then check “allow inheritable permissions of parent to propagate to this object”   4. Once the Inheritable permissions are restored, we need to create a new move request: NOTE:  The EMC can also be used to initiate the Move Request once the permissions are corrected. [PS] c:\>New-moverequest –identity jyoung  -baditemlimit 100 -targetdatabase "mailbox database 1030639620"   And that’s it.  The mailbox should move over smoothly with no access denied error.

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  • Turn-based tile game dynamic item/skill/command script files

    - by user1542
    I want to create a mechanism that could read text script, for example some kind of custom script such as ".skill" or ".item", which maybe contain some sort of simple script like .item Item.Name = "Strength Gauntlet"; Character.STR += 20; .. .skill Skill.Name = "Poison Attack"; Skill.Description = "Steal HP and inflict poison"; Player.HP += 200; Enemy.HP -= 200; Enemy.Status += Status.POISON; It may be different from this, but just want to give some idea of what I desire. However, I do not know how to dynamically parse these things and translate it into working script. For example, in battle scenerio, I should make my game read one of this ".skill" file and apply it to the current enemy, or the current player. How would I do this? Should I go for String parsing? It is like a script engine, but I prefer C# than creating new language, so how would I parse custom files into appropiate status commands? Another problem is, I have also created a command engine which would read String input and parse it into action such as "MOVE (1,2)" would move character to tile (1,2). Each command belong to separate class, and provide generic parsing method that should be implemented by hand. This is for the reason of custom number/type of arguments per each command. However, I think this is not well designed, because I desire it to automatically parse the parameters according to specify list of types. For example, MOVE command in "MOVE 1 2" would automatically parse the parameters into int, int and put it into X and Y. Now, this form can change, and we should be able to manually specify all type of formats. Any suggestion to this problem? Should I change from string parsing to some hardcode methods/classes?

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  • The best way to structure/design game code

    - by Edward
    My question is quite broad and related to the 2D game code design/architecture/structure. Usually the main game consists of the main loop where you update & render your world states. However, it's recommended for many purposes to separate rendering from the game-logic and so on. I am kinda confused about the whole situation. Many game engines/libs/sdks don't follow separation schema. They propagate a way where you define some scenes/stages and they contain some objects and the scene/stage controls the user input and so on. For example, in cocos2d(-x) and libgdx (stage2d) the games are usually done the way that the update logic happens at the same time/place as rendering. Also, the propagated way is to have a structure where an object knows how to draw itself - which is not a separation of updating & rendering. The same with Flash based games, they are usually done the way when an object (class) contains a swf or a texture and some data and holds some update logic itself, or updated from main Scene. And again this object already knows how to draw itself via "addChild". Also, some people recommend to use MVC pattern, which will require to completely obey the structure of those engines/libs/sdks. Maybe I am overthinking everything, but I am totally confused. I would be grateful if somebody could point me to a correct direction with the game code structures. What is your way of doing things in libgdx/cocos2d/flash?

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  • Using XSLT for messaging instead of marshalling/unmarshalling Java message objects

    - by Joost van Stuijvenberg
    So far I have been using either handmade or generated (e.g. JAXB) Java objects as 'carriers' for messages in message processing software such as protocol converters. This often leads to tedious programming, such as copying/converting data from one system's message object to an instance of another's system message object. And it sure brings in lots of Java code with getters and setters for each message attribute, validation code, etc. I was wondering whether it would be a good idea to convert one system's XML message into another system's format - or even convert requests into responses from the same system - using XSLT. This would mean I would no longer have to unmarshall XML streams to Java objects, copy/convert data using Java and marshall the resulting message object to another XML stream. Since each message may actually have a purpose I would 'link' the message (and the payload it contains in its properties or XML elements/attributes) to EXSLT functions. This would change my design approach from an imperative to a declarative style. Has anyone done this before and, if so, what are your experiences? Does the reduced amount of Java 'boiler plate' code weigh up to the increased complexity of (E)XSLT?

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  • nvidia segfault crashes XServer (12.04 fresh install)

    - by Sébastien GILLES
    I am on a fresh install of 12.04, and my video card is a Quadro FX 570, which appears to be supported (see output of unity_support_test below). But my Xserver crashes randomly and causes my session to just shutdown and bring me back to the logging screen. This happens several times per hour. After checking syslog it that a segfault in the nvidia driver is the cause of the problem: Jun 13 11:14:17 lima kernel: [86569.828982] Xorg[17940]: segfault at ffebeb69 ip b4c8f7aa sp bf8076dc error 4 in nvidia_drv.so[b47a7000+706000] Jun 13 11:14:36 lima gnome-session[18119]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Ressource temporairement non disponible) on X server :3.#012 The funny thing is that as I was reporting this bug, my xserver crashed again (!) and this time I got another error message: Jun 13 11:29:39 lima kernel: [87491.106441] NVRM: Xid (0000:02:00): 6, PE0001 Jun 13 11:29:39 lima gnome-session[26493]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Ressource temporairement non disponible) on X server :4.#012 Any idea as to what can be the problem given that i am on a fresh install with a supported video card ? Sébastien == Output of unity_support_test $ /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: Quadro FX 570/PCIe/SSE2 OpenGL version string: 3.3.0 NVIDIA 295.40 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes

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  • Get a culture specific list of month names

    - by erwin21
    A while ago I found a clever way to retrieve a dynamic culture specific list of months names in C# with LINQ. 1: var months = Enumerable.Range(1, 12) 2: .Select(i => new 3: { 4: Month = i.ToString(), 5: MonthName = new DateTime(1, i, 1).ToString("MMMM") 6: }) 7: .ToList(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } It’s fairly simple, for a range of numbers from 1 to 12 a DateTime object is created (year and day doesn’t matter in this case), then the date time object formatted to a full month name with ToString(“MMMM”). In this example an anonymous object is created with a Month and MonthName property. You can use this solution to populate your dropdown list with months or to display a user friendly month name.

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  • PublishingWeb.ExcludeFromNavigation Missing

    - by Michael Van Cleave
    So recently I have had to make the transition from the SharePoint 2007 codebase to SharePoint 2010 codebase. Needless to say there hasn't been much difficulty in the changeover. However in a set of code that I was playing around with and transitioning I did find one change that might cause some pain to others out there that have been programming against the PublishingWeb object in the Microsoft.SharePoint.Publishing namespace. The 2007 snippet of code that work just fine in 2007 looks like: using (SPSite site = new SPSite(url)) using (SPWeb web = site.OpenWeb()) {      PublishingWeb publishingWeb = PublishingWeb.GetPublishingWeb(web);     publishingWeb.ExcludeFromNavigation(true, itemID);     publishingWeb.Update(); } The 2010 update to the code looks like: using (SPSite site = new SPSite(url)) using (SPWeb web = site.OpenWeb()) {     PublishingWeb publishingWeb = PublishingWeb.GetPublishingWeb(web);     publishingWeb.Navigation.ExcludeFromNavigation(true, itemID); //--Had to reference the Navigation object.     publishingWeb.Update(); } The purpose of the code is to keep a page from showing up on the global or current navigation when it is added to the pages library. However you see that the update to the 2010 codebase actually makes more "object" sense. It specifies that you are technically affecting the Navigation of the Publishing Web, instead of the Publishing Web itself. I know that this isn't a difficult problem to fix, but I thought it would be something quick to help out the general public. Michael

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  • Junit test bluej [closed]

    - by user1721929
    Can someone make a junit test of this? public class PersonName { int NumberNames(String wholename) { // store the name passed in to the method String testname=wholename; // initialize number of names found int numnames=0; // on each iteration remove one name while(testname.length()>numnames) { // take the "white space" from the beginning and end testname = testname.trim(); // determine the position of the first blank // .. end of the first word int posBlank= testname.indexOf(' '); // cut off word /** * it continues to the stop sign because that is where you commanded it to end */ testname=testname.substring(posBlank+1,testname.length()); // System.out.println(numnames); // System.out.println(testname); numnames++; System.out.println(testname); } return numnames; } public static void main(String args[]) { PersonName One= new PersonName(); System.out.println(One.NumberNames("Bobby")); System.out.println(One.NumberNames("Bobby Smith")); System.out.println(One.NumberNames("Bobby L. Smith")); System.out.println(One.NumberNames(" Bobby Paul Smith Jr. ")); } }

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  • Is 'Protection' an acceptable Java class name

    - by jonny
    This comes from a closed thread at stack overflow, where there are already some useful answers, though a commenter suggested I post here. I hope this is ok! I'm trying my best to write good readable, code, but often have doubts in my work! I'm creating some code to check the status of some protected software, and have created a class which has methods to check whether the software in use is licensed (there is a separate Licensing class). I've named the class 'Protection', which is currently accessed, via the creation of an appProtect object. The methods in the class allow to check a number of things about the application, in order to confirm that it is in fact licensed for use. Is 'Protection' an acceptable name for such a class? I read somewhere that if you have to think to long in names of methods, classes, objects etc, then perhaps you may not be coding in an Object Oriented way. I've spent a lot of time thinking about this before making this post, which has lead me to doubt the suitability of the name! In creating (and proof reading) this post, I'm starting to seriously doubt my work so far. I'm also thinking I should probably rename the object to applicationProtection rather than appProtect (though am open to any comments on this too?). I'm posting non the less, in the hope that I'll learn something from others views/opinions, even if they're simply confirming I've "done it wrong"!

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