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  • SPSiteDataQuery Returns Only One List Type At A Time

    - by Brian Jackett
    The SPSiteDataQuery class in SharePoint 2007 is very powerful, but it has a few limitations.  One of these limitations that I ran into this morning (and caused hours of frustration) is that you can only return results from one list type at a time.  For example, if you are trying to query items from an out of the box custom list (list type = 100) and document library (list type = 101) you will only get items from the custom list (SPSiteDataQuery defaults to list type = 100.)  In my situation I was attempting to query multiple lists (created from custom list templates 10001 and 10002) each with their own content types. Solution     Since I am only able to return results from one list type at a time, I was forced to run my query twice with each time setting the ServerTemplate (translates to ListTemplateId if you are defining custom list templates) before executing the query.  Below is a snippet of the code to accomplish this. SPSiteDataQuery spDataQuery = new SPSiteDataQuery(); spDataQuery.Lists = "<Lists ServerTemplate='10001' />"; // ... set rest of properties for spDataQuery   var results = SPContext.Current.Web.GetSiteData(spDataQuery).AsEnumerable();   // only change to SPSiteDataQuery is Lists property for ServerTemplate attribute spDataQuery.Lists = "<Lists ServerTemplate='10002' />";   // re-execute query and concatenate results to existing entity results = results.Concat(SPContext.Current.Web.GetSiteData(spDataQuery).AsEnumerable());   Conclusion     Overall this isn’t an elegant solution, but it’s a workaround for a limitation with the SPSiteDataQuery.  I am now able to return data from multiple lists spread across various list templates.  I’d like to thank those who commented on this MSDN page that finally pointed out the limitation to me.  Also a thanks out to Mark Rackley for “name dropping” me in his latest article (which I humbly insist I don’t belong in such company)  as well as encouraging me to write up a quick post on this issue above despite my busy schedule.  Hopefully this post saves some of you from the frustrations I experienced this morning using the SPSiteDataQuery.  Until next time, Happy SharePoint’ing all.         -Frog Out   Links MSDN Article for SPSiteDataQuery http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spsitedataquery.lists.aspx

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  • Using MVP, how to create a view from another view, linked with the same model object

    - by Dinaiz
    Background We use the Model-View-Presenter design pattern along with the abstract factory pattern and the "signal/slot" pattern in our application, to fullfill 2 main requirements Enhance testability (very lightweight GUI, every action can be simulated in unit tests) Make the "view" totally independant from the rest, so we can change the actual view implementation, without changing anything else In order to do so our code is divided in 4 layers : Core : which holds the model Presenter : which manages interactions between the view interfaces (see bellow) and the core View Interfaces : they define the signals and slots for a View, but not the implementation Views : the actual implementation of the views When the presenter creates or deals with views, it uses an abstract factory and only knows about the view interfaces. It does the signal/slot binding between views interfaces. It doesn't care about the actual implementation. In the "views" layer, we have a concrete factory which deals with implementations. The signal/slot mechanism is implemented using a custom framework built upon boost::function. Really, what we have is something like that : http://martinfowler.com/eaaDev/PassiveScreen.html Everything works fine. The problem However, there's a problem I don't know how to solve. Let's take for example a very simple drag and drop example. I have two ContainersViews (ContainerView1, ContainerView2). ContainerView1 has an ItemView1. I drag the ItemView1 from ContainerView1 to ContainerView2. ContainerView2 must create an ItemView2, of a different type, but which "points" to the same model object as ItemView1. So the ContainerView2 gets a callback called for the drop action with ItemView1 as a parameter. It calls ContainerPresenterB passing it ItemViewB In this case we are only dealing with views. In MVP-PV, views aren't supposed to know anything about the presenter nor the model, right ? How can I create the ItemView2 from the ItemView1, not knowing which model object is ItemView1 representing ? I thought about adding an "itemId" to every view, this id being the id of the core object the view represents. So in pseudo code, ContainerPresenter2 would do something like itemView2=abstractWidgetFactory.createItemView2(); this.add(itemView2,itemView1.getCoreObjectId()) I don't get too much into details. That just work. The problem I have here is that those itemIds are just like pointers. And pointers can be dangling. Imagine that by mistake, I delete itemView1, and this deletes coreObject1. The itemView2 will have a coreObjectId which represents an invalid coreObject. Isn't there a more elegant and "bulletproof" solution ? Even though I never did ObjectiveC or macOSX programming, I couldn't help but notice that our framework is very similar to Cocoa framework. How do they deal with this kind of problem ? Couldn't find more in-depth information about that on google. If someone could shed some light on this. I hope this question isn't too confusing ...

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  • Are You In The Know About Knowledge?

    - by [email protected]
    "Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information on it." To me, this simple and elegant quote from the great English author Samuel Johnson is a reflection of Oracle's knowledge base strategy. The knowledge base in the My Oracle Support portal (https://support.oracle.com) hosts nearly a half million documents, including how-to instructions, problem-solution descriptions, code samples, FAQs, critical alerts, technical whitepapers, and so on. AutoVue's footprint in the Oracle knowledge base - although relatively small at just around 400 documents - is a steadily-expanding assortment of valuable info. This information is designed to complement what you have already learned from the AutoVue documentation, or in some cases, to examine topics not yet covered in the documentation. Similar to the documentation, the knowledge base is one of the highest-value self-service avenues, since it delivers answers in real-time and is driven by the topics most relevant to customers. There are many different ways to leverage the AutoVue knowledge content, or what Oracle often refers to as "KM Notes": 1. Knowledge Browser: To browse the knowledge hierarchy, click on the 'Knowledge' tab at the top of the My Oracle Support webpage. In the list of product areas at the left, click on 'More Applications', then on 'Oracle AutoVue'. From here, you can either view the full set of KM Notes under the AutoVue product family (AutoVue, VueLink, Web Services, Document Print Services, etc) by clicking on 'All of Oracle AutoVue', or you can drill down further by clicking on 'Enterprise Visualization'. 2. Search: To execute simple keyword searches, use the Search bar at the top-right of the My Oracle Support webpage: 3. Advanced Search: Beside the same Search bar at the top-right of the My Oracle Support webpage, click on the 'Advanced' link in order to increase your control over the search string as well as the product to search against: 4. In your Dashboard: By clicking on the 'Customize' link at the top-right of the Dashboard page in My Oracle Support, you can drag & drop multiple "Knowledge Articles" widgets onto your dashboard. Then, click on the pencil icon at the top-right of the widget to customize it by product. This allows you to keep an active monitor on the most recently updated KM Notes across any product: 5. During SR Creation: As you submit a new Service Request, after entering the product information, SR title, and SR description, you will be presented with a frame at the left containing KM Note suggestions based on the information entered: Let Oracle know what you think! If you like or dislike an article, or would like to comment on how easy/difficult it was to find the article, click on the "Rate this document" link at the bottom of the KM Note. Similarly, during SR creation if one of the suggested KM Notes resolves your question/issue, you can click the "This article solved my problem" link at the bottom of the page. I hope these approaches improve your ability find knowledge content within the My Oracle Support portal, and I encourage you to continue to build your knowledge to further your success with the AutoVue product family.

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  • Auto Mocking using JustMock

    - by mehfuzh
    Auto mocking containers are designed to reduce the friction of keeping unit test beds in sync with the code being tested as systems are updated and evolve over time. This is one sentence how you define auto mocking. Of course this is a more or less formal. In a more informal way auto mocking containers are nothing but a tool to keep your tests synced so that you don’t have to go back and change tests every time you add a new dependency to your SUT or System Under Test. In Q3 2012 JustMock is shipped with built in auto mocking container. This will help developers to have all the existing fun they are having with JustMock plus they can now mock object with dependencies in a more elegant way and without needing to do the homework of managing the graph. If you are not familiar with auto mocking then I won't go ahead and educate you rather ask you to do so from contents that is already made available out there from community as this is way beyond the scope of this post. Moving forward, getting started with Justmock auto mocking is pretty simple. First, I have to reference Telerik.JustMock.Container.DLL from the installation folder along with Telerik.JustMock.DLL (of course) that it uses internally and next I will write my tests with mocking container. It's that simple! In this post first I will mock the target with dependencies using current method and going forward do the same with auto mocking container. In short the sample is all about a report builder that will go through all the existing reports, send email and log any exception in that process. This is somewhat my  report builder class looks like: Reporter class depends on the following interfaces: IReporBuilder: used to  create and get the available reports IReportSender: used to send the reports ILogger: used to log any exception. Now, if I just write the test without using an auto mocking container it might end up something like this: Now, it looks fine. However, the only issue is that I am creating the mock of each dependency that is sort of a grunt work and if you have ever changing list of dependencies then it becomes really hard to keep the tests in sync. The typical example is your ASP.NET MVC controller where the number of service dependencies grows along with the project. The same test if written with auto mocking container would look like: Here few things to observe: I didn't created mock for each dependencies There is no extra step creating the Reporter class and sending in the dependencies Since ILogger is not required for the purpose of this test therefore I can be completely ignorant of it. How cool is that ? Auto mocking in JustMock is just released and we also want to extend it even further using profiler that will let me resolve not just interfaces but concrete classes as well. But that of course starts the debate of code smell vs. working with legacy code. Feel free to send in your expert opinion in that regard using one of telerik’s official channels. Hope that helps

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  • Is the science of Computer Science dead?

    - by Veaviticus
    Question : Is the science and art of CS dead? By that I mean, the real requirements to think, plan and efficiently solve problems seems to be falling away from CS these days. The field seems to be lowering the entry-barrier so more people can 'program' without having to learn how to truly program. Background : I'm a recent graduate with a BS in Computer Science. I'm working a starting position at a decent sized company in the IT department. I mostly do .NET and other Microsoft technologies at my job, but before this I've done Java stuff through internships and the like. I personally am a C++ programmer for my own for-fun projects. In Depth : Through the work I've been doing, it seems to me that the intense disciplines of a real science don't exist in CS anymore. In the past, programmers had to solve problems efficiently in order for systems to be robust and quick. But now, with the prevailing technologies like .NET, Java and scripting languages, it seems like efficiency and robustness have been traded for ease of development. Most of the colleagues that I work with don't even have degrees in Computer Science. Most graduated with Electrical Engineering degrees, a few with Software Engineering, even some who came from tech schools without a 4 year program. Yet they get by just fine without having the technical background of CS, without having studied theories and algorithms, without having any regard for making an elegant solution (they just go for the easiest, cheapest solution). The company pushes us to use Microsoft technologies, which take all the real thought out of the matter and replace it with libraries and tools that can auto-build your project for you half the time. I'm not trying to hate on the languages, I understand that they serve a purpose and do it well, but when your employees don't know how a hash-table works, and use the wrong sorting methods, or run SQL commands that are horribly inefficient (but get the job done in an acceptable time), it feels like more effort is being put into developing technologies that coddle new 'programmers' rather than actually teaching people how to do things right. I am interested in making efficient and, in my opinion, beautiful programs. If there is a better way to do it, I'd rather go back and refactor it than let it slide. But in the corporate world, they push me to complete tasks quickly rather than elegantly. And that really bugs me. Is this what I'm going to be looking forward to the rest of my life? Are there still positions out there for people who love the science and art of CS rather than just the paycheck? And on the same note, here's a good read if you haven't seen it before The Perils Of Java Schools

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  • Using commands with ApplicationBarMenuItem and ApplicationBarButton in Windows Phone 7

    - by Laurent Bugnion
    Unfortunately, in the current version of the Windows Phone 7 Silverlight framework, it is not possible to attach any command on the ApplicationBarMenuItem and ApplicationBarButton controls. These two controls appear in the Application Bar, for example with the following markup: <phoneNavigation:PhoneApplicationPage.ApplicationBar> <shell:ApplicationBar x:Name="MainPageApplicationBar"> <shell:ApplicationBar.MenuItems> <shell:ApplicationBarMenuItem Text="Add City" /> <shell:ApplicationBarMenuItem Text="Add Country" /> </shell:ApplicationBar.MenuItems> <shell:ApplicationBar.Buttons> <shell:ApplicationBarIconButton IconUri="/Resources/appbar.feature.video.rest.png" /> <shell:ApplicationBarIconButton IconUri="/Resources/appbar.feature.settings.rest.png" /> <shell:ApplicationBarIconButton IconUri="/Resources/appbar.refresh.rest.png" /> </shell:ApplicationBar.Buttons> </shell:ApplicationBar> </phoneNavigation:PhoneApplicationPage.ApplicationBar> This code will create the following UI: Application bar, collapsed Application bar, expanded ApplicationBarItems are not, however, controls. A quick look in MSDN shows the following hierarchy for ApplicationBarMenuItem, for example: Unfortunately, this prevents all the mechanisms that are normally used to attach a Command (for example a RelayCommand) to a control. For example, the attached behavior present in the class ButtonBaseExtension (from the Silverlight 3 version of the MVVM Light toolkit) can only be attached to a DependencyObject. Similarly, Blend behaviors (such as EventToCommand from the toolkit’s Extras library) needs a FrameworkElement to work. Using code behind The alternative is to use code behind. As I said in my MIX10 talk, the MVVM police will not take your family away if you use code behind (this quote was actually suggested to me by Glenn Block); the code behind is there for a reason. In our case, invoking a command in the ViewModel requires the following code: In MainPage.xaml: <shell:ApplicationBarMenuItem Text="My Menu 1" Click="ApplicationBarMenuItemClick"/> In MainPage.xaml.cs private void ApplicationBarMenuItemClick( object sender, System.EventArgs e) { var vm = DataContext as MainViewModel; if (vm != null) { vm.MyCommand.Execute(null); } } Conclusion Resorting to code behind to bridge the gap between the View and the ViewModel is less elegant than using attached behaviors, either through an attached property or through a Blend behavior. It does, however, work fine. I don’t have any information if future changes in the Windows Phone 7 Application Bar API will make this easier. In the mean time, I would recommend using code behind instead.   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Excel tables creation upon MySQL data import (new feature in MySQL for Excel 1.2.x)

    - by Javier Treviño
    In this blog post we are going to talk about one of the features included since MySQL for Excel 1.2.0, you can install the latest GA or maintenance version using the MySQL Installer or optionally you can download directly any GA or non-GA version from the MySQL Developer Zone. Remember how easy is to dump data from a MySQL table, view or stored procedure to an Excel worksheet? (If you don't you can check out this other post: How To - Guide to Importing Data from a MySQL Database to Excel using MySQL for Excel). In version 1.2.0 we introduced some advanced options for the Import MySQL Data operation regarding Excel tables. The Advanced Options dialog shown above is accessible from any Import Data dialog. When the Create an Excel table for the imported MySQL table data option is checked (which is by default), MySQL for Excel will create an Excel table (also known in Excel jargon as a ListObject) from the Excel range containing the imported MySQL data. This "little feature" enables the right-away usage of the Excel table in data analysis, like including it for summarization on a PivotTable, including a summarization row at the end of the table's data, sorting or filtering the table's data by clicking the drop-down button next to each column's header, among other actions. The Excel tables that are created automatically from imported MySQL data will have a name like [UserPrefix].<SchemaName>.<DbObjectName> for tables and views, and <Prefix>.<SchemaName>.<ProcedureName>.<ResultSetName> for stored procedures.  Notice the first piece of the name is an optional [UserPrefix], the prefix is only used if the Prefix Excel tables with the following text option is checked, notice that the suggested prefix is "MySQL" but it can be changed to whatever text is suitable for you. Excel tables must have a table style so they are easily identified. There are a lot of predefined Excel table styles, by default the MySqlDefault style is applied, which is the style you have seen applied to imported data for Edit Sessions, and which adds simple and elegant formatting to the table. If you wish to change it to any of the predefined Excel table style you can do it through the drop-down list on the Use style [[styles drop-down]] for the new Excel table option. Excel tables are the basic construction blocks for building data analysis or self-service Business Intelligence using other more advanced Excel tools like Power Pivot, Power View or Power Map. This feature empowers imported MySQL data to use it in more advanced ways.  We hope you give this and the other new features in the 1.2.x version family a try! Remember that your feedback is very important for us, so drop us a message and follow us: MySQL on Windows (this) Blog: https://blogs.oracle.com/MySqlOnWindows/ MySQL for Excel forum: http://forums.mysql.com/list.php?172 Facebook: http://www.facebook.com/mysql YouTube channel: https://www.youtube.com/user/MySQLChannel Cheers!

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  • Log Debug Messages without Debug Serial on Shipped Device

    - by Kate Moss' Open Space
    Debug message is one of the ancient but useful way for problem resolving. Message is redirected to PB if KITL is enabled otherwise it goes to default debug port, usually a serial port on most of the platform but it really depends on how OEMWriteDebugString and OEMWriteDebugByte are implemented. For many reasons, we don't want to have a debug serial port, for example, we don't have enough spare serial ports and it can affect the performance. So some of the BSP designers decide to dump the messages into other media, could be a log file, shared memory or any solution that is suitable for the need. In CE 5.0 and previous, OAL and Kernel are linked into one binaries; in the other word, you can use whatever function in kernel, such as SC_CreateFileW to access filesystem in OAL, even this is strongly not recommended. But since the OAL is being a standalone executable in CE 6.0, we no longer can use this back door but only interface exported in NKGlobal which just provides enough for OAL but no more. Accessing filesystem or using sync object to communicate to other drivers or application is even not an option. Sounds like the kernel lock itself up; of course, OAL is in kernel space, you can still do whatever you want to hack into kernel, but once again, it is not only make it a dirty solution but also fragile. So isn't there an elegant solution? Let's see how a debug message print out. In private\winceos\COREOS\nk\kernel\printf.c, the OutputDebugStringW is the one for pumping out the messages; most of the code is for error handling and serialization but what really interesting is the following code piece     if (g_cInterruptsOff) {         OEMWriteDebugString ((unsigned short *)str);     } else {         g_pNKGlobal->pfnWriteDebugString ((unsigned short *)str);     }     CELOG_OutputDebugString(dwActvProcId, dwCurThId, str); It outputs the message to default debug output (is redirected to KITL when available) or OAL when needed but note that highlight part, it also invokes CELOG_OutputDebugString. Follow the thread to private\winceos\COREOS\nk\logger\CeLogInstrumentation.c, this function dump whatever input to CELOG. So whatever the debug message is we always got a clone in CELOG. General speaking, all of the debug message is logged to CELOG already, so what you need to do is using celogflush.exe with CELZONE_DEBUG zone, and then viewing the data using the by Readlog tool. Here are some information about these tools CELOG - http://msdn.microsoft.com/en-us/library/ee479818.aspx READLOG - http://msdn.microsoft.com/en-us/library/ee481220.aspx Also for advanced reader, I encourage you to dig into private\winceos\COREOS\nk\celog\celogdll, the source of CELOG.DLL and use it as a starting point to create a more lightweight debug message logger for your own device!

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  • Extending Currying: Partial Functions in Javascript

    - by kerry
    Last week I posted about function currying in javascript.  This week I am taking it a step further by adding the ability to call partial functions. Suppose we have a graphing application that will pull data via Ajax and perform some calculation to update a graph.  Using a method with the signature ‘updateGraph(id,value)’. To do this, we have do something like this: 1: for(var i=0;i<objects.length;i++) { 2: Ajax.request('/some/data',{id:objects[i].id},function(json) { 3: updateGraph(json.id, json.value); 4: } 5: } This works fine.  But, using this method we need to return the id in the json response from the server.  This works fine, but is not that elegant and increase network traffic. Using partial function currying we can bind the id parameter and add the second parameter later (when returning from the asynchronous call).  To do this, we will need the updated curry method.  I have added support for sending additional parameters at runtime for curried methods. 1: Function.prototype.curry = function(scope) { 2: scope = scope || window 3: var args = []; 4: for (var i=1, len = arguments.length; i < len; ++i) { 5: args.push(arguments[i]); 6: } 7: var m = this; 8: return function() { 9: for (var i=0, len = arguments.length; i < len; ++i) { 10: args.push(arguments[i]); 11: } 12: return m.apply(scope, args); 13: }; 14: } To partially curry this method we will call the curry method with the id parameter, then the request will callback on it with just the value.  Any additional parameters are appended to the method call. 1: for(var i=0;i<objects.length;i++) { 2: var id=objects[i].id; 3: Ajax.request('/some/data',{id: id}, updateGraph.curry(id)); 4: } As you can see, partial currying gives is a very useful tool and this simple method should be a part of every developer’s toolbox.

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  • Using lookahead assertions in regular expressions

    - by Greg Jackson
    I use regular expressions on a daily basis, as my daily work is 90% in Perl (legacy codebase, but that's a different issue). Despite this, I still find lookahead and lookbehind to be terribly confusing and often unreadable. Right now, if I were to get a code review with a lookahead or lookbehind, I would immediately send it back to see if the problem can be solved by using multiple regular expressions or a different approach. The following are the main reasons I tend not to like them: They can be terribly unreadable. Lookahead assertions, for example, start from the beginning of the string no matter where they are placed. That, among other things, can cause some very "interesting" and non-obvious behaviors. It used to be the case that many languages didn't support lookahead/lookbehind (or supported them as "experimental features"). This isn't the case quite as much, but there's still always the question as to how well it's supported. Quite frankly, they feel like a dirty hack. Regexps often already are, but they can also be quite elegant, and have gained widespread acceptance. I've gotten by without any need for them at all... sometimes I think that they're extraneous. Now, I'll freely admit that especially the last two reasons aren't really good ones, but I felt that I should enumerate what goes through my mind when I see one. I'm more than willing to change my mind about them, but I feel that they violate some of my core tenets of programming, including: Code should be as readable as possible without sacrificing functionality -- this may include doing something in a less efficient, but clearer was as long as the difference is negligible or unimportant to the application as a whole. Code should be maintainable -- if another programmer comes along to fix my code, non-obvious behavior can hide bugs or make functional code appear buggy (see readability) "The right tool for the right job" -- I'm sure you can come up with contrived examples that could use lookahead, but I've never come across something that really needs them in my real-world development work. Is there anything that they're really the best tool for, as opposed to, say, multiple regexps (or, alternatively, are they the best tool for most cases they're used for today). My question is this: Is it good practice to use lookahead/lookbehind in regular expressions, or are they simply a hack that have found their way into modern production code? I'd be perfectly happy to be convinced that I'm wrong about this, and simple examples are useful for examples or illustration, but by themselves, won't be enough to convince me.

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  • introducing pointers to a large software project

    - by stefan
    I have a fairly large software project written in c++. In there, there is a class foo which represents a structure (by which i don't mean the programmers struct) in which foo-objects can be part of a foo-object. Here's class foo in simplest form: class Foo { private: std::vector<unsigned int> indices; public: void addFooIndex(unsigned int); unsigned int getFooIndex(unsigned int); }; Every foo-object is currently stored in an object of class bar. class Bar { private: std::vector<Foo> foos; public: void addFoo(Foo); std::vector<Foo> getFoos(); } So if a foo-object should represent a structure with a "inner" foo-object, I currently do Foo foo; Foo innerFoo; foo.addFooIndex(bar.getFoos().size() - 1); bar.addFoo(innerFoo); And to get it, I obviously use: Foo foo; for ( unsigned int i = 0; i < foo.getFooIndices().size(); ++i ) { Foo inner_foo; assert( foo.getFooIndices().at(i) < bar.getFoos().size() ); inner_foo = bar.getFoos().at(foo.getFooIndices().at(i)); } So this is not a problem. It just works. But it's not the most elegant solution. I now want to make the inner foos to be "more connected" with the foo-object. It would be obviously to change class foo to: class Foo { private: std::vector<Foo*> foo_pointers; public: void addFooPointer(Foo*); std::vector<Foo*> getFooPointers(); }; So now, for my question: How to gently change this basic class without messing up the whole code? Is there a "clean way"?

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  • Diving into Scala with Cay Horstmann

    - by Janice J. Heiss
    A new interview with Java Champion Cay Horstmann, now up on otn/java, titled  "Diving into Scala: A Conversation with Java Champion Cay Horstmann," explores Horstmann's ideas about Scala as reflected in his much lauded new book,  Scala for the Impatient.  None other than Martin Odersky, the inventor of Scala, called it "a joy to read" and the "best introduction to Scala". Odersky was so enthused by the book that he asked Horstmann if the first section could be made available as a free download on the Typesafe Website, something Horstmann graciously assented to. Horstmann acknowledges that some aspects of Scala are very complex, but he encourages developers to simply stay away from those parts of the language. He points to several ways Java developers can benefit from Scala: "For example," he says, " you can write classes with less boilerplate, file and XML handling is more concise, and you can replace tedious loops over collections with more elegant constructs. Typically, programmers at this level report that they write about half the number of lines of code in Scala that they would in Java, and that's nothing to sneeze at. Another entry point can be if you want to use a Scala-based framework such as Akka or Play; you can use these with Java, but the Scala API is more enjoyable. " Horstmann observes that developers can do fine with Scala without grasping the theory behind it. He argues that most of us learn best through examples and not through trying to comprehend abstract theories. He also believes that Scala is the most attractive choice for developers who want to move beyond Java and C++.  When asked about other choices, he comments: "Clojure is pretty nice, but I found its Lisp syntax a bit off-putting, and it seems very focused on software transactional memory, which isn't all that useful to me. And it's not statically typed. I wanted to like Groovy, but it really bothers me that the semantics seems under-defined and in flux. And it's not statically typed. Yes, there is Groovy++, but that's in even sketchier shape. There are a couple of contenders such as Kotlin and Ceylon, but so far they aren't real. So, if you want to do work with a statically typed language on the JVM that exists today, Scala is simply the pragmatic choice. It's a good thing that it's such a nice choice." Learn more about Scala by going to the interview here.

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  • What are the arguments against parsing the Cthulhu way?

    - by smarmy53
    I have been assigned the task of implementing a Domain Specific Language for a tool that may become quite important for the company. The language is simple but not trivial, it already allows nested loops, string concatenation, etc. and it is practically sure that other constructs will be added as the project advances. I know by experience that writing a lexer/parser by hand -unless the grammar is trivial- is a time consuming and error prone process. So I was left with two options: a parser generator à la yacc or a combinator library like Parsec. The former was good as well but I picked the latter for various reasons, and implemented the solution in a functional language. The result is pretty spectacular to my eyes, the code is very concise, elegant and readable/fluent. I concede it may look a bit weird if you never programmed in anything other than java/c#, but then this would be true of anything not written in java/c#. At some point however, I've been literally attacked by a co-worker. After a quick glance at my screen he declared that the code is uncomprehensible and that I should not reinvent parsing but just use a stack and String.Split like everybody does. He made a lot of noise, and I could not convince him, partially because I've been taken by surprise and had no clear explanation, partially because his opinion was immutable (no pun intended). I even offered to explain him the language, but to no avail. I'm positive the discussion is going to re-surface in front of management, so I'm preparing some solid arguments. These are the first few reasons that come to my mind to avoid a String.Split-based solution: you need lot of ifs to handle special cases and things quickly spiral out of control lots of hardcoded array indexes makes maintenance painful extremely difficult to handle things like a function call as a method argument (ex. add( (add a, b), c) very difficult to provide meaningful error messages in case of syntax errors (very likely to happen) I'm all for simplicity, clarity and avoiding unnecessary smart-cryptic stuff, but I also believe it's a mistake to dumb down every part of the codebase so that even a burger flipper can understand it. It's the same argument I hear for not using interfaces, not adopting separation of concerns, copying-pasting code around, etc. A minimum of technical competence and willingness to learn is required to work on a software project after all. (I won't use this argument as it will probably sound offensive, and starting a war is not going to help anybody) What are your favorite arguments against parsing the Cthulhu way?* *of course if you can convince me he's right I'll be perfectly happy as well

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  • How do I prevent having to log in on 3 separate prompts every time I start my machine?

    - by JC
    Ubuntu 11.04 Natty Narwhal, Ubuntu Classic desktop Each time I start my machine, I have to log in 3 times. I spent a week in IRCFreenode#ubuntu and got nothing but condescension. I've searched on the official Ubuntu fora for similar problems, tried every recommendation, and still get 3 login screens. As a workaround, I have reset login such that I get a login screen at startup, which I'd prefer not to get since this machine is accessible by no one but me, physically. I have gone into System Preferences Passwords and Encryption Keys, set first 'Passwords: default' to 'Default' and unlocked it, and unlocked the 'Passwords: login' key, too. Next, since that changed nothing, I set 'Passwords: login' to 'Default', and checked to make sure it was still unlocked. Again, no change, still get 3 login prompts at startup. I've checked twice to insure that I am the owner of the files; I am. At the suggestion of several people in #ubuntu, I've deleted first one, then the other password key in 'Passwords and Encryption Keys'. Still get 3 login prompts. I changed from the Unity desktop to Ubuntu Classic. While that didn't fix the above problem, it is a much more elegant desktop than Unity, and I'll keep it. From what I've read, this seems to be a Seahorse issue, but beyond that, no one seems to have a solution that works. I'm lost. This shouldn't be this difficult or annoying. I'm trying to help our local Old Time music collective get their machines switched over to Ubuntu in order to save them some money which they can use to promote their DRM-free music. But from what I've seen of Ubuntu so far on my own machine, I can't really recommend that they make this switch. I hope to be proved wrong on that point. But as it stands, if I was out of town or out of country and they ran into a problem, they'd have no way of fixing it as they're all less experienced than even I am. I'm not trying to cast aspersions on Ubuntu or Linux, but it seems pretty clear that KNOWLEDGEABLE, HELPFUL support for Ubuntu is lacking barring any desire on the problem-experiencing-user's part to avoid condescension. Having worked with, and run, several non-profits over the past 20 years, I know that getting volunteers to act professionally can be like herding cats. But an organization's reputation can be denigrated by sarcastic behaviors on the part of those who serve, effectively, as its public face. Thank you all for your help and support. Now...does anyone have a solution to my problem?

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  • How can I dynamically load the correct sprite from a sprite sheet?

    - by Leonard Challis
    I am making a simple card game in unity. The game is based on a standard 52-card pack, with identical backs for unique faces. In my particular game different cards are worth different values and have various special abilities. The game will have 52 cards on the table (on the draw position or in the face-down deck or in someone's hand) at all times, so this number won't change. I thought that making a Card prefab and instantiating 52 of these manually would be a bad idea. Even doing it in code, I thought, would be a bit OTT, and that I should just instantiate visual cards when they are face-up to the player. I have a sprite sheet of the 52 cards and the back, which is imported as a Sprite in multiple mode, sliced in to a grid containing all the cards needed to play the game. The problem I now face is that, through my GameController script I want to generate a shuffled pack of cards, deal some to each player and then show those cards to a player. However, I am not sure of the best way, or even if it's possible, to do this dynamically with the sprite sheets as they are. For instance if I have the following: private CardRank rank; private CardSuite suite; private void Start() { this.rank = CardRank.Ace; this.suite = CardSuite.Spades; } This class would be instantiated by the game manager. I would have 52 of these in code. Whenever I have to visually show a card in the scene, I would use a card prefab, which is essentially a game object with a SpriteRenderer on it. I would need to dynamically load the correct sprite for this object from the spritesheet. The sliced sprites from the sprite sheet actually have names in the format AS (Ace of Spades), 7H (Seven of Hearts), etc - though this was a manual thing I did myself of course. I have also tried various alternative solutions, including creating animations, having separate sprites not in a spritesheet and having an array of available sprites in an array with a specific index for each card, but none seem as elegant as trying to load the correct sprite at runtime, as I'm trying to. So, how do I load a specific sprite from a spritesheet at runtime? I'm open to suggestions, even those that make me think differently about how to approach the problem.

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  • Minimizing Dependencies For GUIs

    - by tuba09
    I've been working on a project, and have been charged with designing the projects GUI front-end. I'm coding in Java and using the Swing toolkit. Usability-wise, the GUI front-end follows all of Nielsen's heuristics. Users can easily get to where they want to go through the click of a button / JComboBox. Essentially, in Swing terms, what happens is their actions drive the creation/deletion of custom panels. The GUI is coming along fine for the most part. However, I have to admit to being utterly dismayed at the tight web of dependencies my code is being smothered in. The main problem that I've encountered, that I haven't been able to fix as of yet, is how to keep a reference to the panels/buttons being changed. I'll give an example: Say there's a button A Say there's a panel B displaying picture C Say there's another picture D (not currently being displayed by panel B) When user clicks A, panel B should remove picture C and display picture D My question is, what's the best way of keeping track of panel B? Since I need a global point of access to panel B, my solution has so far been to just shoehorn it into a static variable, and access it through a series of static getters and setters. And this static variable is usually stored in the reference's original class. I.e. UserPanel has a static variable that stores a reference to itself. Is there an easy, tried-and-true way of dealing with these kinds of situations? Like my GUI works fine, but it is not modular and/or robust at all. To add to this, the dreaded 'cyclical dependencies' issue that's shunned by so many programmers is out here in full effect. I'm fairly new to development and just want to make sure that my code will be fairly extensible and won't cause much of a headache to the next person that decides to get a try at it. I know there's loads of books out there that probably have a nice elegant solution to this, but unfortunately I just don't have the time to leisure read right now. I need something that's quick and dirty. Thanks in advance

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  • What can I do to make sure my code gets maintained in a developer light environment?

    - by asjohnson
    I am a contract data analyst, so I bounce between jobs every 3-6 months, which I find to be a good fit for me, but it leads to some problems when it comes to coding. I mostly do statistics (I've asked a similar question on cross validated, but the answers there are not relevant here), but I have also found out that the business world loves excel and loves copying and pasting the same thing over and over again even more. This led me to learn how to write VBA scripts and then VB.NET programs to automate as many of these reports as I can. I am certain my programs are not the most elegant, but I put a good bit of effort into making sure they work under as many cases as I can test, I add in exceptions and try to code so the program can handle changes in the files that it processes, but there is a limit, if you remove a huge portion of the data, there is a good chance my program is going to trip up, which I accept will inevitably happen. Usually a pretty minor change in the code fixes the problem and I do try and comment my code and make it readable under the assumption that some other person will have to read it some day. My problem is that I generally get put on teams of folks with essentially no experience with programming (like VBA would be a huge stretch for anyone I work directly with). I am wondering what I should be doing as the person that wrote the code to do my best to keep it maintained. I have two approaches in mind (outlined next), but would be very happy to get any advice. Solution 1: Find the more tech savvy coworkers and run them through the programs and what basic changes can be made. Honestly automating excel is about as easy as it can get when it comes to programming, so I feel like I could teach someone the basics of maintaining it pretty quick. Solution 2: Get in touch with the IT department and show them what is going on and maybe they will be able to help. The problem here is that the IT department is constantly swamped (as I'm sure many of you know) and I feel like kind of a jerk for dumping more things on them. I do leave my personal email address with places and am willing to answer quick questions via email, but I view the need for more exhaustive maintenance as something of an inevitability and would like to make sure I do my due diligence to make sure it gets done. I imagine some combination of the two approaches outlined there, but is there any kind of heads up I should give IT? I feel like I would be annoyed if I started getting requests to fix a program that I had never seen from some random guy that is no longer there.

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  • Reporting on common code smells : A POC

    - by Dave Ballantyne
    Over the past few blog entries, I’ve been looking at parsing TSQL scripts in a variety of ways for a variety of tasks.  In my last entry ‘How to prevent ‘Select *’ : The elegant way’, I looked at parsing SQL to report upon uses of SELECT *.  The obvious question leading on from this is, “Great, what about other code smells ?”  Well, using the language service parser to do that was turning out to be a bit of a hard job,  sure I was getting tokens but no real context.  I wasn't even being told when an end of statement had been reached. One of the other parsing options available from Microsoft is exposed in the assembly ‘Microsoft.SqlServer.TransactSql.ScriptDom’,  this is ,I believe, installed with the client development tools with SQLServer.  It is much more feature rich than the original parser I had used and breaks a TSQL script into intuitive classes for analysis. So, what sort of smells can I now find using it ?  Well, for an opening gambit quite a nice little list. Use of NOLOCK Set of READ UNCOMMITTED Use of SELECT * Insert without column references Explicit datatype conversion on Sargs Cross server selects Non use of two-part naming convention Table and Query hint usage Changes in set options Use of single line comments Use of ordinal column positions in ORDER BY clause Now, lets not argue the point that “It depends” as smells on some of these, but as an academic exercise it is quite interesting.  The code is available from this link :https://www.dropbox.com/s/rfk32sou4fzl2cw/TSQLDomTest.zip  All the usual disclaimers apply to this code, I cannot be held responsible for anything ranging from mild annoyance through to universe destruction due to the use of this code or examples. The zip file contains a powershell script and my test cases.  The assembly used requires .Net 4 to run, which means that you will need powershell 3 ( though im running through PowerGUI and all works ok ) .  The code searches for all .sql files in the folder hierarchy for the workingpath,  you can override this if you want by simply changing the $Folder variable, and processes each in turn for the smells.  Feedback is not great at the moment, all it does is output to an xml file (Smells.xml) the offset position and a description of the smell found. Right now, I am interested in your feedback.  What do you think ?  Is this (or should it be) more than an academic exercise ?  Can tooling such as this be used as some form of code quality measure ?  Does it Work ? Do you have a case listed above which is not being reported ? Do you have a case that you would love to be reported ? Let me know , please mailto: [email protected]. Thanks

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  • design a model for a system of dependent variables

    - by dbaseman
    I'm dealing with a modeling system (financial) that has dozens of variables. Some of the variables are independent, and function as inputs to the system; most of them are calculated from other variables (independent and calculated) in the system. What I'm looking for is a clean, elegant way to: define the function of each dependent variable in the system trigger a re-calculation, whenever a variable changes, of the variables that depend on it A naive way to do this would be to write a single class that implements INotifyPropertyChanged, and uses a massive case statement that lists out all the variable names x1, x2, ... xn on which others depend, and, whenever a variable xi changes, triggers a recalculation of each of that variable's dependencies. I feel that this naive approach is flawed, and that there must be a cleaner way. I started down the path of defining a CalculationManager<TModel> class, which would be used (in a simple example) something like as follows: public class Model : INotifyPropertyChanged { private CalculationManager<Model> _calculationManager = new CalculationManager<Model>(); // each setter triggers a "PropertyChanged" event public double? Height { get; set; } public double? Weight { get; set; } public double? BMI { get; set; } public Model() { _calculationManager.DefineDependency<double?>( forProperty: model => model.BMI, usingCalculation: (height, weight) => weight / Math.Pow(height, 2), withInputs: model => model.Height, model.Weight); } // INotifyPropertyChanged implementation here } I won't reproduce CalculationManager<TModel> here, but the basic idea is that it sets up a dependency map, listens for PropertyChanged events, and updates dependent properties as needed. I still feel that I'm missing something major here, and that this isn't the right approach: the (mis)use of INotifyPropertyChanged seems to me like a code smell the withInputs parameter is defined as params Expression<Func<TModel, T>>[] args, which means that the argument list of usingCalculation is not checked at compile time the argument list (weight, height) is redundantly defined in both usingCalculation and withInputs I am sure that this kind of system of dependent variables must be common in computational mathematics, physics, finance, and other fields. Does someone know of an established set of ideas that deal with what I'm grasping at here? Would this be a suitable application for a functional language like F#? Edit More context: The model currently exists in an Excel spreadsheet, and is being migrated to a C# application. It is run on-demand, and the variables can be modified by the user from the application's UI. Its purpose is to retrieve variables that the business is interested in, given current inputs from the markets, and model parameters set by the business.

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  • Design pattern to handle queries using multiple models

    - by coderkane
    I am presented with a dilemma while trying to re-designing the class structure for my PHP/MySQL application to make it more elegant and conform it to the SOLID principle. The problem goes like this: Let as assume, there is an abstract class called person which has certain properties to define a generic person, such as name, age, date of birth etc. There are two classes, student, and teacher, that implements this abstract class. They add their own unique properties to it. I have designed all the three classes to include all the operational logic (details of which are not relevant in context of the question). Now, I need to create views/reports/data grids which contain details from multiple classes, for example, say, a list of all students doing projects in Chemistry mentored by a teacher whose name is the parameter to the query. This is just one example of a view, there are many different views in the application, which uses data from 3-4 tables, and each of them have multiple input parameters to generate them. Considering this particular example, I have written the relevant query using JOIN and the results are as expected and proper, now here is the dilemma: Keeping in mind the single responsibility principle, where should I keep this query? It does not belong to either Student class, or Teacher class or any other classes currently present. a) Should I create a new class, say dataView class, and design it as a MVC pattern and keep the query there? What about the other views? how do they fit in this architecture? b) Should I not keep the query in code at all, and make it DB View ? c) Am I completely wrong in the approach? If so what is the right approach? My considerations are as follows: a) should be easy to add new views later on if requirement comes, without having to copy-paste-modify code b) would like to make it as loosely coupled as possible so that if minor db structure changes happen, it does not break I did google searches on report design and OOP report generators, but all the result seem to focus on the visual design of the report rather than fetching the data. I have already taken care of the visual aspect of the report using MVC with html templates. I am sure this is a very fundamental problem with known solution, but I am somehow not able to find it (maybe searching with wrong keyword). Edit1: Modified the title to make it more relevant Edit2: The accepted answer got me thinking in the right direction and identify my design flaws, which eventually led me to find this question and the solution in Stack Overflow which gave me the detailed answer to clear the confusion.

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  • why are my players drawn to the side of my viewport

    - by Jetbuster
    Following this admittedly brilliant and clean 2d camera class I have a camera on each player, and it works for multiplayer and i've divided the screen into two sections for split screen by giving each camera a viewport. However in the game it looks like this I'm not sure if thats their position relative to the screen or what The relevant gameScreen code, the makePlayers is setup so it could theoretically work for up to 4 players private void makePlayers() { int rowCount = 1; if (NumberOfPlayers > 2) rowCount = 2; players = new Player[NumberOfPlayers]; for (int i = 0; i < players.Length; i++) { int xSize = GameRef.Window.ClientBounds.Width / 2; int ySize = GameRef.Window.ClientBounds.Height / rowCount; int col = i % rowCount; int row = i / rowCount; int xPoint = 0 + xSize * row; int yPoint = 0 + ySize * col; Viewport viewport = new Viewport(xPoint, yPoint, xSize, ySize); Vector2 playerPosition = new Vector2(viewport.TitleSafeArea.X + viewport.TitleSafeArea.Width / 2, viewport.TitleSafeArea.Y + viewport.TitleSafeArea.Height / 2); players[i] = new Player(playerPosition, playerSprites[i], GameRef, viewport); } //players[1].Keyboard = true; } public override void Draw(GameTime gameTime) { base.Draw(gameTime); foreach (Player player in players) { GraphicsDevice.Viewport = player.PlayerCamera.ViewPort; GameRef.spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.PointClamp, null, null, null, player.PlayerCamera.Transform); map.Draw(GameRef.spriteBatch); // Draw the Player player.Draw(GameRef.spriteBatch); // Draw UI screen elements GraphicsDevice.Viewport = Viewport; ControlManager.Draw(GameRef.spriteBatch); GameRef.spriteBatch.End(); } } the player's initialize and draw methods are like so internal void Initialize() { this.score = 0; this.angle = (float)(Math.PI * 0 / 180);//Start sprite at it's default rotation int width = utils.scaleInt(picture.Width, imageScale); int height = utils.scaleInt(picture.Height, imageScale); this.hitBox = new HitBox(new Vector2(centerPos.X - width / 2, centerPos.Y - height / 2), width, height, Color.Black, game.Window.ClientBounds); playerCamera.Initialize(); } #region Methods public void Draw(SpriteBatch spriteBatch) { //Console.WriteLine("Hitbox: X({0}),Y({1})", hitBox.Points[0].X, hitBox.Points[0].Y); //Console.WriteLine("Image: X({0}),Y({1})", centerPos.X, centerPos.Y); Vector2 orgin = new Vector2(picture.Width / 2, picture.Height / 2); hitBox.Draw(spriteBatch); utils.DrawCrosshair(spriteBatch, Position, game.Window.ClientBounds, Color.Red); spriteBatch.Draw(picture, Position, null, Color.White, angle, orgin, imageScale, SpriteEffects.None, 0.1f); } as I said I think I'm gonna need to do something with the render position but I'm to entirely sure what or how it would be elegant to say the least

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  • Was I wrong about JavaScript?

    - by jboyer
    Yes, I was. Recently, I’ve taken a good hard look at JavaScript. I’ve used it before but mostly in the capacity of web design. Using JQuery to make your web page do cool stuff is different than really creating a JavaScript application using all of the language constructs. What I’m finding as I use it more is that I may have been wrong about my assumptions about it. Let me explain.   I enjoyed doing cool stuff with JQuery but the limited experience with JavaScript as a language coupled with the bad things that I heard about it led me to not have any real interest in it. However, JavaScript is ubiquitous on the web and if I want to do any web development, which I do, I need to learn it. So here I am, diving deep into the language with the help of the JavaScript Fundamentals training course at Pluralsight (great training for a low price) and the JavaScript: The Good Parts book by Douglas Crockford.   Now, there are certainly parts of JavaScript that are bad. I think these are well known by any developer that uses it. The parts that I feel are especially egregious are the following: The global object null vs. undefined truthy and falsy limited (nearly nonexistent) scoping ‘==’ and ‘===’ (I just don’t get the reason for coercion)   However, what I am finding hiding under the covers of the bad things is a good language. I am finding that I am legitimately enjoying JavaScript. This I was not expecting. I’m not going to go into a huge dissertation on what I like about it, but some things include: Object literal notation dynamic typing functional style (JavaScript: The Good Parts describes it as LISP in C clothing) JSON (better than XML) There are parts of JavaScript that seem strange to OOP developers like myself. However, just because it is different or seems strange does not mean it is bad. Some differences are quite interesting and useful.   I feel that it is important for developers to challenge their assumptions and also to be able to admit when they are wrong on a topic. Many different situations can arise that lead to this, such as choosing the wrong technology for a problem’s solution, misunderstanding the requirements, etc. I decided to challenge my assumptions about JavaScript instead of moving straight into CoffeeScript or Dart. After exploring it, I find that I am beginning to enjoy it the more I use it. As long as there are those like Crockford to help guide me in the right way to code in JavaScript, I can create elegant and efficient solutions to problems and add another ‘arrow’ to the ‘quiver’, so to speak. I do still intend to learn CoffeeScript to see what the hub-bub is about, but now I no longer have to be afraid of JavaScript as a legitimate programming language.   Has something similar ever happened to you? Tell me about it in the comments below.

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  • Does it make the game more fun when the user is forced to progress thru the levels sequentially rather than letting them pick and play?

    - by BeachRunnerJoe
    Hello. For the first time in my game, I'm stuck with a real design dilemma. I guess that's a good thing ;) I'm building a word puzzle game that has five levels, each with 30 puzzles. Currently, the user has to solve one puzzle at a time before moving to the next. However, I'm finding the user occasionally gets stuck on a puzzle, at which point they can no longer play until they solve it. This is obviously bad because many people will just quit playing the game and delete the app since they get frustrated and can't play any other puzzles until the current puzzle is solved. The only elegant solution I can find to helping the player get unstuck is changing the design of the game to allow the users to pick any puzzle to play at any time. This way, if they get stuck, they can come back to it later and at least they have other puzzles to play in the meantime. It's my opinion, however, that this new flow design doesn't make the game as fun as the original flow design where the player has to complete a puzzle before moving to the next. To me, it's like anything else, when you only have one of something, it's more enjoyable, but when you have 30 of something, it's far less enjoyable. In fact, when I present the user with 30 puzzles to choose from that they need to solve before unlocking the next level, it almost seems as tho I'm making them feel like it's work they have to do. I even had a tester voluntarily tell me that being forced to complete a puzzle before moving to the next is more motivating. My questions are... Do you agree/disagree? Do you have any suggestions for how I can help the player get unstuck? Thanks so much in advance for your thoughts! EDIT: I should mention that I've already considered a few other solutions to helping the user get unstuck, but none of them seem like good ideas. They are... Add more hints: Currently, the user gets two hints per puzzle. If I increase the hint count, it only makes the game more easy and still leaves the possibility of the user getting stuck. Add a "Show Solution" button: This seems like a bad idea because it's my opinion this takes the fun out of the game for many people who would probably otherwise solve the puzzle if they didn't have the quick option to see the solution.

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  • How to properly do weapon cool-down reload timer in multi-player laggy environment?

    - by John Murdoch
    I want to handle weapon cool-down timers in a fair and predictable way on both client on server. Situation: Multiple clients connected to server, which is doing hit detection / physics Clients have different latency for their connections to server ranging from 50ms to 500ms. They want to shoot weapons with fairly long reload/cool-down times (assume exactly 10 seconds) It is important that they get to shoot these weapons close to the cool-down time, as if some clients manage to shoot sooner than others (either because they are "early" or the others are "late") they gain a significant advantage. I need to show time remaining for reload on player's screen Clients can have clocks which are flat-out wrong (bad timezones, etc.) What I'm currently doing to deal with latency: Client collects server side state in a history, tagged with server timestamps Client assesses his time difference with server time: behindServerTimeNs = (behindServerTimeNs + (System.nanoTime() - receivedState.getServerTimeNs())) / 2 Client renders all state received from server 200 ms behind from his current time, adjusted by what he believes his time difference with server time is (whether due to wrong clocks, or lag). If he has server states on both sides of that calculated time, he (mostly LERP) interpolates between them, if not then he (LERP) extrapolates. No other client-side prediction of movement, e.g., to make his vehicle seem more responsive is done so far, but maybe will be added later So how do I properly add weapon reload timers? My first idea would be for the server to send each player the time when his reload will be done with each world state update, the client then adjusts it for the clock difference and thus can estimate when the reload will be finished in client-time (perhaps considering also for latency that the shoot message from client to server will take as well?), and if the user mashes the "shoot" button after (or perhaps even slightly before?) that time, send the shoot event. The server would get the shoot event and consider the time shot was made as the server time when it was received. It would then discard it if it is nowhere near reload time, execute it immediately if it is past reload time, and hold it for a few physics cycles until reload is done in case if it was received a bit early. It does all seem a bit convoluted, and I'm wondering whether it will work (e.g., whether it won't be the case that players with lower ping get better reload rates), and whether there are more elegant solutions to this problem.

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  • How to apply effects that occur (or change) over time to characters in a game?

    - by Joshua Harris
    So assume that I have a system that applies Effects to Characters like so: public class Character { private Collection<Effect> _effects; public void AddEffect (Effect e) { e.ApplyTo(this); _effects.Add(e); } public void RemoveEffect (Effect e) { e.RemoveFrom(this); _effects.Remove(e); } } public interface Effect { public void ApplyTo (Character character); public void RemoveFrom (Character character); } Example Effect: Armor Buff for 5 seconds. void someFunction() { // Do Stuff ... Timer armorTimer = new Timer(5 seconds); ArmorBuff armorbuff = new ArmorBuff(); character.AddEffect(armorBuff); armorTimer.Start(); // Do more stuff ... } // Some where else in code public void ArmorTimer_Complete() { character.RemoveEffect(armorBuff); } public class ArmorBuff implements Effect { public void applyTo(Character character) { character.changeArmor(20); } public void removeFrom(Character character) { character.changeArmor(-20); } } Ok, so this example would buff the Characters armor for 5 seconds. Easy to get working. But what about effects that change over the duration of the effect being applied. Two examples come to mind: Damage Over Time: 200 damage every second for 3 seconds. I could mimic this by applying an Effect that lasts for 1 second and has a counter set to 3, then when it is removed it could deal 200 damage, clone itself, decrement the counter of the clone, and apply the clone to the character. If it repeats this until the counter is 0, then you got a damage over time ability. I'm not a huge fan of this approach, but it does describe the behavior exactly. Degenerating Speed Boost: Gain a speed boost that degrades over 3 seconds until you return to your normal speed. This is a bit harder. I can basically do the same thing as above except having timers set to some portion of a second, such that they occur fast enough to give the appearance of degenerating smoothly over time (even though they are really just stepping down incrementally). I feel like you could get away with only 12 steps over a second (maybe less, I would have to test it and see), but this doesn't seem very elegant to me. The only other way to implement this effect would be to change the system so that the Character checks the _effects collection for effects that alter any of the properties any time that they are being used. I could handle this in functions like getCurrentSpeed() and getCurrentArmor(), but you can imagine how much of a hassle it would be to have that kind of overhead every time you want to do a calculation with movement speed (which would be every time you move your character). Is there a better way to deal with these kinds of effects or events?

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