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  • Getting from a user-story to code while using TDD (scrum)

    - by Ittai
    I'm getting into scrum and TDD and I think I have some confusion which I'd like to get your feedback about. Let's assume I have a user-story in my backlog, in order for me to start developing it as part of TDD I need to have requirements, right so far? Is it true to say that the product manager and the QA should be responsible for taking the user-story and breaking it down to acceptance tests? I think the above is true since the acceptance tests need to be formal, so they can be used as tests, but also human readable so that the product can approve they are the requirements, right? Is it also true that I later take these acceptance tests and use them as my requirements, i.e. they are a set of use-cases which I implement (through TDD)? I hope I'm not making too much of a mess but that's the current flow I have in mind right now. Update I think my initial intentions were unclear so I'll try to rephrase. I want to know more details about the scrum flow of turning a user-story into code while using TDD. The starting point is obvious, a user surfaces a need (or the user's representative as the product) which is a short 1-2 lines description in the known format and that is added to the product backlog. When there is a spring planning meeting user-stories are taken from the backlog and assigned to developers. In order for a developer to write code they need requirements (especially in TDD since the requirements are what the tests are derived from). When, by whom and to which format are the requirements compiled? What I had in mind was that the product and QA define the requirements via acceptance tests (I'm thinking of automatic using FitNesse or the sort but that's not the core I think) which help to serve 2 purposes at the same time: They define "Done" properly. They give a developer something to derive tests from. I wasn't sure when these were written (before the sprint they're picked then that might be a waste since additional information will arrive or the story won't be picked, during the iteration then the developer might get stuck waiting for them...)

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  • Space partitioning when everything is moving

    - by Roy T.
    Background Together with a friend I'm working on a 2D game that is set in space. To make it as immersive and interactive as possible we want there to be thousands of objects freely floating around, some clustered together, others adrift in empty space. Challenge To unburden the rendering and physics engine we need to implement some sort of spatial partitioning. There are two challenges we have to overcome. The first challenge is that everything is moving so reconstructing/updating the data structure has to be extremely cheap since it will have to be done every frame. The second challenge is the distribution of objects, as said before there might be clusters of objects together and vast bits of empty space and to make it even worse there is no boundary to space. Existing technologies I've looked at existing techniques like BSP-Trees, QuadTrees, kd-Trees and even R-Trees but as far as I can tell these data structures aren't a perfect fit since updating a lot of objects that have moved to other cells is relatively expensive. What I've tried I made the decision that I need a data structure that is more geared toward rapid insertion/update than on giving back the least amount of possible hits given a query. For that purpose I made the cells implicit so each object, given it's position, can calculate in which cell(s) it should be. Then I use a HashMap that maps cell-coordinates to an ArrayList (the contents of the cell). This works fairly well since there is no memory lost on 'empty' cells and its easy to calculate which cells to inspect. However creating all those ArrayLists (worst case N) is expensive and so is growing the HashMap a lot of times (although that is slightly mitigated by giving it a large initial capacity). Problem OK so this works but still isn't very fast. Now I can try to micro-optimize the JAVA code. However I'm not expecting too much of that since the profiler tells me that most time is spent in creating all those objects that I use to store the cells. I'm hoping that there are some other tricks/algorithms out there that make this a lot faster so here is what my ideal data structure looks like: The number one priority is fast updating/reconstructing of the entire data structure Its less important to finely divide the objects into equally sized bins, we can draw a few extra objects and do a few extra collision checks if that means that updating is a little bit faster Memory is not really important (PC game)

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  • Microsoft Introduces WebMatrix

    - by Rick Strahl
    originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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  • Am I experienced enough to learn and develop immediately using Ruby on Rails?

    - by acheong87
    General Question I understand that discussions revolving around questions of this form run the risk of becoming too specific to help others. So, perhaps a better, general question would be: What kind of experience, if any, translates easily to Ruby on Rails; and if none, then what's the learning curve like, in comparison to other popular languages? Background I have the opportunity to build a website using whatever technologies I wish to use. It's a fairly simple website, for listing products, taking payments, managing customer data, providing a back-end portal for employees to manage data, possibly hooking in flight information (the products are travel related), possibly integrating a blog and all the social-networking goodies. Specific Problem I have to let the client know by tonight whether I'm interested in taking up this project, before he talks to other potential developers, but I'm on the fence. I already work a full-time C++ development job, so the money doesn't do it for me. It's the opportunity to (be paid to) learn some new technologies and to have a real, running product in the end. I've heard and read great things about Ruby, and am really intrigued. I zipped through some introductory Ruby tutorials, no sweat. However I found the Rails tutorials a little overwhelming, especially not being able to try it out anywhere. And researching Rails hosts like Heroku and EngineYard makes me think that maybe I don't know what I'm getting myself into. The ship's leaving port! I wish I had more time to learn, better yet play with the language, but I have to decide soon! Should I venture or pass? Additional Details My experiences are in C/C++/Tcl/Perl/PHP/jQuery, and basic knowledge of Java/C#. I didn't study C.S. formally so I wasn't exposed to design principles, programming paradigms, etc., which is my greatest concern. Will my lack of understanding in this realm make RoR frustrating to learn? Will it be so incompatible with a C++ "way" of thinking that I'll wish I never started? Am I putting my client at risk by attempting this? If it helps, I'm quick to learn new things (self-taught so far) and care a great deal about correctness, using things for their intended purposes, and so on. I've read numerous recommendations of Agile Development with Rails and would love to read it (though perhaps, while developing in parallel, for shortness of time). Worse comes to worst, I'd give up and do the standard LAMP gig, of course, not charging the client for wasted time. But I'm hoping to avoid the project altogether if it's gonna come down to that! Thanks in advance for any tips, insights, votes of confidence, votes of discouragement (for the better), and such.

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  • Au revoir, Python?

    - by GuySmiley
    I'm an ex-C++ programmer who's recently discovered (and fallen head-over-heels with) Python. I've taken some time to become reasonably fluent in Python, but I've encountered some troubling realities that may lead me to drop it as my language of choice, at least for the time being. I'm writing this in the hopes that someone out there can talk me out of it by convincing me that my concerns are easily circumvented within the bounds of the python universe. I picked up python while looking for a single flexible language that will allow me to build end-to-end working systems quickly on a variety of platforms. These include: - web services - mobile apps - cross-platform client apps for PC Development speed is more of a priority at the time-being than execution speed. However, in order to improve performance over time without requiring major re-writes or architectural changes I think it's imperative to be able to interface easily with Java. That way, I can use Java to optimize specific components as the application scales, without throwing away any code. As far as I can tell, my requirement for an enterprise-capable, platform-independent, fast language with a large developer base means it would have to be Java. .NET or C++ would not cut it due to their respective limitations. Also Java is clearly de rigeur for most mobile platforms. Unfortunately, tragically, there doesn't seem to be a good way to meet all these demands. Jython seems to be what I'm looking for in principle, except that it appears to be practically dead, with no one developing, supporting, or using it to any great degree. And also Jython seems too married to the Java libraries, as you can't use many of the CPython standard libraries with it, which has a major impact on the code you end up writing. The only other option that I can see is to use JPype wrapped in marshalling classes, which may work although it seems like a pain and I wonder if it would be worth it in the long run. On the other hand, everything I'm looking for seems to be readily available by using JRuby, which seems to be much better supported. As things stand, I think this is my best option. I'm sad about this because I absolutely love everything about Python, including the syntax. The perl-like constructs in Ruby just feel like such a step backwards to me in terms of readability, but at the end of the day most of the benefits of python are available in Ruby as well. So I ask you - am I missing something here? Much of what I've said is based on what I've read, so is this summary of the current landscape accurate, or is there some magical solution to the Python-Java divide that will snuff these concerns and allow me to comfortably stay in my happy Python place?

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  • A Quick HLSL Question (How to modify some HLSL code)

    - by electroflame
    Thanks for wanting to help! I'm trying to create a circular, repeating ring (that moves outward) on a texture. I've achieved this, to a degree, with the following code: float distance = length(inTex - in_ShipCenter); float time = in_Time; ///* Simple distance/time combination */ float2 colorIndex = float2(distance - time, .3); float4 shipColor = tex2D(BaseTexture, inTex); float4 ringColor = tex2D(ringTexture, colorIndex); float4 finalColor; finalColor.rgb = (shipColor.rgb) + (ringColor.rgb); finalColor.a = shipColor.a; // Use the base texture's alpha (transparency). return finalColor; This works, and works how I want it to. The ring moves outward from the center of the texture at a steady rate, and is constrained to the edges of the base texture (i.e. it won't continue past an edge). However, there are a few issues with it that I would like some help on, though. They are: By combining the color additively (when I set finalColor.rgb), it makes the resulting ring color much lighter than I want (which, is pretty much the definition of additive blending, but I don't really want additive blending in this case). I would really like to be able to pass in the color that I want the ring to be. Currently, I have to pass in a texture that contains the color of the ring, but I think that doing it that way is kind of wasteful and overly-cumbersome. I know that I'm probably being an idiot over this, so I greatly appreciate the help. Some other (possibly relevant) information: I'm using XNA. I'm applying this by providing it to a SpriteBatch (as an Effect). The SpriteBatch is using BlendState.NonPremultiplied. Thanks in advance! EDIT: Thanks for the answers thus far, as they've helped me get a better grasp of the color issue. However, I'm still unsure of how to pass a color in and not use a texture. i.e. Can I create a tex2D by using a float4 instead of a texture? Or can I make a texture from a float4 and pass the texture in to the tex2D? DOUBLE EDIT: Here's some example pictures: With the effect off: With the effect on: With the effect on, but with the color weighting set to full: As you can see, the color weighting makes the base texture completely black (The background is black, so it looks transparent). You can also see the red it's supposed to be, and then the white-ish it really is when blended additively.

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  • XNA 2D line-of-sight check

    - by bionicOnion
    I'm working on a top-down shooter in XNA, and I need to implement line-of-sight checking. I've come up with a solution that seems to work, but I get the nagging feeling that it won't be efficient enough to do every frame for multiple calls (the game already hiccups slightly at about 10 calls per frame). The code is below, but my general plan was to create a series of rectangles with a width and height of zero to act as points along the sight line, and then check to see if any of these rectangles intersects a ClutterObject (an interface I defined for things like walls or other obstacles) after first screening for any that can't possibly be in the line of sight (i.e. behind the viewer) or are too far away (a concession I made for efficiency). public static bool LOSCheck(Vector2 pos1, Vector2 pos2) { Vector2 currentPos = pos1; Vector2 perMove = (pos2 - pos1); perMove.Normalize(); HashSet<ClutterObject> clutter = new HashSet<ClutterObject>(); foreach (Room r in map.GetRooms()) { if (r != null) { foreach (ClutterObject c in r.GetClutter()) { if (c != null &&!(c.GetRectangle().X * perMove.X < 0) && !(c.GetRectangle().Y * perMove.Y < 0)) { Vector2 cVector = new Vector2(c.GetRectangle().X, c.GetRectangle().Y); if ((cVector - pos1).Length() < 1500) clutter.Add(c); } } } } while (currentPos != pos2 && ((currentPos - pos1).Length() < 1500)) { Rectangle position = new Rectangle((int)currentPos.X, (int)currentPos.Y, 0, 0); foreach (ClutterObject c in clutter) { if (position.Intersects(c.GetRectangle())) return false; } currentPos += perMove; } return true; } I'm sure that there's a better way to do this (or at least a way to make this method more efficient), but I'm not too used to XNA yet, so I figured it couldn't hurt to bring it here. At the very least, is there an efficient to determine which objects may be in front of the viewer with greater precision than the rather broad 90 degree window I've given myself?

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  • How to shoot a triangle out of an asteroid which floats all of the way up to the screen?

    - by Holland
    I currently have an asteroid texture loaded as my "test player" for the game I'm writing. What I'm trying to figure out how to do is get a triangle to shoot from the center of the asteroid, and keep going until it hits the top of the screen. What happens in my case (as you'll see from the code I've posted), is that the triangle will show, however it will either be a long line, or it will just be a single triangle which stays in the same location as the asteroid moving around (that disappears when I stop pressing the space bar), or it simply won't appear at all. I've tried many different methods, but I could use a formula here. All I'm trying to do is write a space invaders clone for my final in C#. I know how to code fairly well, my formulas just need work is all. So far, this is what I have: Main Logic Code protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(ClearOptions.Target, Color.Black, 1, 1); mAsteroid.Draw(mSpriteBatch); if (mIsFired) { mPositions.Add(mAsteroid.LastPosition); mRay.Fire(mPositions); mIsFired = false; mRay.Bullets.Clear(); mPositions.Clear(); } base.Draw(gameTime); } Draw Code public void Draw() { VertexPositionColor[] vertices = new VertexPositionColor[3]; int stopDrawing = mGraphicsDevice.Viewport.Width / mGraphicsDevice.Viewport.Height; for (int i = 0; i < mRayPos.Length(); ++i) { vertices[0].Position = new Vector3(mRayPos.X, mRayPos.Y + 5f, 10); vertices[0].Color = Color.Blue; vertices[1].Position = new Vector3(mRayPos.X - 5f, mRayPos.Y - 5f, 10); vertices[1].Color = Color.White; vertices[2].Position = new Vector3(mRayPos.X + 5f, mRayPos.Y - 5f, 10); vertices[2].Color = Color.Red; mShader.CurrentTechnique.Passes[0].Apply(); mGraphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleStrip, vertices, 0, 1); mRayPos += new Vector2(0, 1f); mGraphicsDevice.ReferenceStencil = 1; } }

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  • Ed Burns' Servlet 4/HTTP 2 Session at JavaOne 2014

    - by reza_rahman
    For the Java EE track at JavaOne 2014 we are highlighting some key sessions and speakers to better inform you of what you can expect, right up until the start of the conference. To this end we recently interviewed Ed Burns. Ed is a veteran of Sun and now Oracle. He has been and is instrumental in pushing the JSF ecosystem forward as specification lead. Besides his specification lead work Ed is well regarded as an author and speaker on his own right. In addition to carrying the JSF torch Ed will be co-leading the key Servlet 4 specification for Java EE 8, along with Servlet specification guru Shing Wai Chan. The primary goal of Servlet 4 is to enable the fundamentally important changes in HTTP 2 for the entire server-side Java ecosystem. We wanted to talk to Ed about his Servlet 4 session at JavaOne 2014 and HTTP 2 generally: The details for the Servlet 4 session can be found here. Ed has several other key sessions on the track that we hope to talk to him about separately in the near future: What’s Next for JSF?: In this key session, Ed will be sharing the next steps for the continued evolution of the JSF specification in Java EE 8. Where’s My UI? The 2014 JavaOne Web App UI Smackdown: The UI space for web applications, especially in the Java ecosystem continues to be as hotly contested as ever. This is especially true with the (re)introduction of JavaScript based rich client frameworks like AngularJS. This lively panel brings together experts representing the diverse schools of thought for web UIs. Ed will be representing JSF of course. Neal Ford will moderate the panel as an independent and hopefully reasonably neutral party. Adopt-a-JSR for Java EE 7 and Java EE 8: Adopt-a-JSR has been a reasonable success for Java EE 7. With Java EE 8 we are planning to strengthen it far more as away of getting grassroots level participation in the specification efforts. This session will introduce Adopt-a-JSR, share how it worked for Java EE 7 and what we plan to do with it in Java EE 8. Ed will be sharing his perspectives on Adopt-a-JSR for both Java EE 7 and Java EE 8. Besides Ed's sessions, we have a very strong program for the Java EE track and JavaOne overall - just explore the content catalog. If you can't make it, you can be assured that we will make key content available after the conference just as we have always done.

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  • How do you play or record audio (to .WAV) on Linux in C++? [closed]

    - by Jacky Alcine
    Hello, I've been looking for a way to play and record audio on a Linux (preferably Ubuntu) system. I'm currently working on a front-end to a voice recognition toolkit that'll automate a few steps required to adapt a voice model for PocketSphinx and Julius. Suggestions of alternative means of audio input/output are welcome, as well as a fix to the bug shown below. Here is the current code I've used so far to play a .WAV file: void Engine::sayText ( const string OutputText ) { string audioUri = "temp.wav"; string requestUri = this->getRequestUri( OPENMARY_PROCESS , OutputText.c_str( ) ); int error , audioStream; pa_simple *pulseConnection; pa_sample_spec simpleSpecs; simpleSpecs.format = PA_SAMPLE_S16LE; simpleSpecs.rate = 44100; simpleSpecs.channels = 2; eprintf( E_MESSAGE , "Generating audio for '%s' from '%s'..." , OutputText.c_str( ) , requestUri.c_str( ) ); FILE* audio = this->getHttpFile( requestUri , audioUri ); fclose(audio); eprintf( E_MESSAGE , "Generated audio."); if ( ( audioStream = open( audioUri.c_str( ) , O_RDONLY ) ) < 0 ) { fprintf( stderr , __FILE__": open() failed: %s\n" , strerror( errno ) ); goto finish; } if ( dup2( audioStream , STDIN_FILENO ) < 0 ) { fprintf( stderr , __FILE__": dup2() failed: %s\n" , strerror( errno ) ); goto finish; } close( audioStream ); pulseConnection = pa_simple_new( NULL , "AudioPush" , PA_STREAM_PLAYBACK , NULL , "openMary C++" , &simpleSpecs , NULL , NULL , &error ); for (int i = 0;;i++ ) { const int bufferSize = 1024; uint8_t audioBuffer[bufferSize]; ssize_t r; eprintf( E_MESSAGE , "Buffering %d..",i); /* Read some data ... */ if ( ( r = read( STDIN_FILENO , audioBuffer , sizeof (audioBuffer ) ) ) <= 0 ) { if ( r == 0 ) /* EOF */ break; eprintf( E_ERROR , __FILE__": read() failed: %s\n" , strerror( errno ) ); if ( pulseConnection ) pa_simple_free( pulseConnection ); } /* ... and play it */ if ( pa_simple_write( pulseConnection , audioBuffer , ( size_t ) r , &error ) < 0 ) { fprintf( stderr , __FILE__": pa_simple_write() failed: %s\n" , pa_strerror( error ) ); if ( pulseConnection ) pa_simple_free( pulseConnection ); } usleep(2); } /* Make sure that every single sample was played */ if ( pa_simple_drain( pulseConnection , &error ) < 0 ) { fprintf( stderr , __FILE__": pa_simple_drain() failed: %s\n" , pa_strerror( error ) ); if ( pulseConnection ) pa_simple_free( pulseConnection ); } } NOTE: If you want the rest of the code to this file, you can download it here directly from Launchpad.

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  • What to do if I am working on a language that I don't like

    - by Sayem Ahmed
    Hi there, I really don't know if this is the right place to ask this question, but if it isn't, then I guess someone will notify. Anyway, I am working in a software development farm which is currently using PowerBuilder to develop a mid-size ERP solution. The work environment and company management are so great that it may be the best in the whole Bangladesh. Only problem is the technology that are currently being used, which is this PowerBuilder. Now I am a guy who tends to prefer modern development technologies, like DI containers, ORM, TDD, JQuery etc. PowerBuilder is a great tool too, but I couldn' like the application techniques used to build PB applications. These techniques are so inheritance-dependent that many a times these create a great deal of sufferings. I remember two days ago I had to change some processing logic in a core user object and as a result I had to test and re-test all the forms that the application have(apparently, there are almost 20 forms there, each of them with 3-4 kinds of functionalities). Also, learning PB is tough, because online material on this thing is very, very low. I can't afford to read all the documentation that PB provide because I have hard deadlines on the work that I have to do. Another thing with PB is that applications tend to rely on business logic that are implemented on databases which causes debugging to be a nightmare. As a result, I don't feel motivated enough to work in this IDE/System/Framework (or whatever) anymore. My productivity has greatly decreased, and I am not delivering quality code. I think I have the following options available to me - Remain in the current job, keep delivering worse code and let my productivity decrease day by day, taking salaries and bonuses but not delivering quality codes/doing my job the way I should, Search for a new job. At this point number 2 seems a good option, but there are also some issues. As I mentioned before, our management may be the best in the country. Our company owner is himself a software developer with 24 years of experience in software development. He is currently our Team Leader and System Analyst. He is by far the greatest manager and boss I have ever seen. He understands developer's mentality very well(as he IS himself a developer). He is also a great, kind and generous guy. Our company is only a start-up company with 10 developers. Among them, only 3-4 people knows about the business logic behind the ERP, and I am one of them. If I switch my current job, it may hamper the development of this product which I really don't want. I couldn't decide what to do in this situation, so I turned to the community for advice.

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  • Github Organization Repositories, Issues, Multiple Developers, and Forking - Best Workflow Practices

    - by Jim Rubenstein
    A weird title, yes, but I've got a bit of ground to cover I think. We have an organization account on github with private repositories. We want to use github's native issues/pull-requests features (pull requests are basically exactly what we want as far as code reviews and feature discussions). We found the tool hub by defunkt which has a cool little feature of being able to convert an existing issue to a pull request, and automatically associate your current branch with it. I'm wondering if it is best practice to have each developer in the organization fork the organization's repository to do their feature work/bug fixes/etc. This seems like a pretty solid work flow (as, it's basically what every open source project on github does) but we want to be sure that we can track issues and pull requests from ONE source, the organization's repository. So I have a few questions: Is a fork-per-developer approach appropriate in this case? It seems like it could be a little overkill. I'm not sure that we need a fork for every developer, unless we introduce developers who don't have direct push access and need all their code reviewed. In which case, we would want to institute a policy like that, for those developers only. So, which is better? All developers in a single repository, or a fork for everyone? Does anyone have experience with the hub tool, specifically the pull-request feature? If we do a fork-per-developer (or even for less-privileged devs) will the pull-request feature of hub operate on the pull requests from the upstream master repository (the organization's repository?) or does it have different behavior? EDIT I did some testing with issues, forks, and pull requests and found that. If you create an issue on your organization's repository, then fork the repository from your organization to your own github account, do some changes, merge to your fork's master branch. When you try to run hub -i <issue #> you get an error, User is not authorized to modify the issue. So, apparently that work flow won't work.

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  • Importing PKCS#12 (.p12) files into Firefox From the Command Line

    - by user11165
    I’ve posted this question up on #Ubuntu and #Firefox Forums, and really could do with some help.. Anyone know where i could look or help with the answer. I’m hoping the power of social media will come through… I have a need to perform the following action: Firefox 3.6.x: Quote: open Edit - Preferences - Advanced - Encryption - View Certificates - Your Certificates - Import However i need the same functionality from the bash command line. So far I’ve established that the following command is supposed to be used: Quote: certutil -A -t “u,u,u” -d /home/df001/.mozilla/firefox/qe5y5lht.tc.default/ -n “mycert” -i client.p12 This executes with no isses, however, doesn’t show up in any Firefox Certificate store. However, I have noted that prior to running this command, i have a cert8.db key3.db and secmod.db file in the above folder. After running the command the certutil seems to have created a cert9.db, key4.db and pkcs12.txt file Listing the contents using the command: Quote: certutil -L -d sql:/home/df001/.mozilla/firefox/qe5y5lht.tc.default/ does seem to confirm my attempts of importing files into a certificate folder of some kind have worked. because i get Quote: Certificate Nickname Trust Attributes SSL,S/MIME,JAR/XPI Thawte SSL CA „ Go Daddy Secure Certification Authority „ Thawte SGC CA „ Entrust Certification Authority - L1C „ My Nero CT,C,c mynero P„ davidfield - Internet Widgits Pty Ltd u,u,u So, having tried this, and heading back over to the www, i cam across this command: Quote: pk12util -d /home/df001/.mozilla/firefox/qe5y5lht.tc.default/ -i client.p12 -n “David Field” -P “cert8.db” this again, appears to be importing something somewhere, however, again, Viewing certs from the Firefox interface doesn’t show the imported Cert. I’m surmising here on reading that the certutil and pk12util are creating a new NSS database, which firefox isn’t reading. So my question is, how can i get the p12 cert from the command line so it displays in the firefox Certificate manager interface? Why have i posted this here? Why not post on the firefox forum? Well i will copy and post the same question there as well, however the ability to use the command line to do this is important, as I have potentially 2000 machines which will need a user cert imported into firefox via a p12 file. I need to do this in the form of a script, i thought the hard part was going to be making the p12 file from the microsoft 2003 CA, turns out thats easy. I can’t just import via the GUI and copy over cert8.db x 2000, i can’t ask users to use the CA webinterface as its for VPN access, the users are off site, and they need the VPN to get to the cert server.. Is there any person out there who can help? By the way, i don't have the tor buttun installed.

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  • Follow the How-To Geek Writers on Twitter

    - by The Geek
    Ever wonder what the How-To Geek writers are up to? If you’re a Twitter user, you can connect with us directly. We’ve also setup a new @howtogeeknews account if you just want to keep up with the latest articles. So if you want just the latest articles… click the image below and then click the Follow button. Otherwise, if you’d like to connect with the rest of us that actually use Twitter, you can follow each of us separately through  the links below. Note: Let’s try to stick to discussion, and leave the tech support questions for our forum. the How-To Geek (that’s me!) -  @howtogeek Matthew Guay – @maguay Trevor Bekolay – @TrevorBekolay Asian Angel – @asian_angel  Andrew Gehman – @andrewgehman Some of the HTG writers are not currently using Twitter… but I’m gonna list their accounts just in case you wanted to follow them. Mark Virtue – @markvirtue Mysticgeek – @mysticgeek  (He’s far too productive to waste time on Twitter!) Enjoy the conversation! Similar Articles Productive Geek Tips Got Awesome Geek Skills? The How-To Geek is Looking for WritersGot Awesome Skills? Why Not Write for How-To Geek?Integrate Twitter With Microsoft OutlookState of the Geek 2009: Behind the Scenes and Other GeekeryAnnouncing the How-To Geek Blogs TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Download Videos from Hulu Pixels invade Manhattan Convert PDF files to ePub to read on your iPad Hide Your Confidential Files Inside Images Get Wildlife Photography Tips at BBC’s PhotoMasterClasses Mashpedia is a Real-time Encyclopedia

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  • Mexico leading in Business Transformation Strategies:

    - by [email protected]
    By John Burke Group Vice President Oracle Applications Business Unit     I recently completed a business tour in Mexico, and was surprised by both the economic vibrancy of the country and the thought leadership expressed by many of the customers I met.  An example of the economic vibrancy of the country: across the street from my hotel was the local Bentley dealership, Coach Store, Yves Saint Laurent and of course a Starbucks.  I only made it to Starbucks.  Both the Coach Store and YSL had a line of folks waiting to get in... As for thought leadership, there were several illustrations only on the first day. I had the opportunity to meet with a branch of the Mexican Federal Government. Their questions were not about clerical task automation, far from it! We discussed citizen on-line access to fees and services - for example looking up the duty on an international goods shipment, or tracking that my taxes have been received, or the status of my request for a certain service.  Eligibility, policies and status.  Having an integrated rules or policy automation system that would allow businesses and citizens to access accurate information and ensure the proper collection of fees and payment for 3rd party provided services.    Then in the afternoon, I met with the owner of a roofing company (note: most roofs in Mexico are flat and made of cement).  This CEO started discussing how he wanted to transform his business from a cement products company to a service company and market 5-10-15 year service contracts which would guarantee the structural integrity of the roof and of course that the roof would remain waterproof.  Although his products were guaranteed, they required an annual inspection and most home owners never schedule that inspection until it is too late and water damage has occurred.  These emergency calls reduce his margin and reduce customer satisfaction.  This lead to a discussion of business models in general and why long term differentiation can only come from service, not just for the music or news industries, but also for roofing companies!    I completely agreed with the transformational concepts described in both meetings and quickly understood why there is a Bentley dealership near my hotel.    

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  • Keep taking the tablets

    - by Roger Hart
    A guest editorial for the SimpleTalk newsletter. So why would Red Gate build an Ipad Game? Is it just because tablet devices are exciting and cool? Ok, maybe a little. Mostly, it was seeing that the best existing tablet and smartphone apps do simple, intuitive things, using simple intuitive interfaces to solve single problems. That's pretty close to what we call our own "intuitively simple" approach to software. Tablets and mobile could be fantastic for us, if we can identify those problems that a tablet device can solve. How do you create THE next tool for a completely new technology? We're glad we don't face that problem every day, but it's pretty exciting when we do. We figure we should learn by doing. We created "MobileFoo" (a Red Gate Company) , we picked up some shiny Apple tech, and got to grips with Objective C, and life in the App Store ecosystem. The result so far is an iPad game: Stacks and Heaps It's Rob and Marine's spin on Snakes and Ladders. Instead of snakes we have unhandled exceptions, a blue screen of death, and other hazards. We wanted something compellingly geeky on mobile, and we're pretty sure we've got it. It's trudging through App Store approval as we speak. but if you want to get an idea of what it is like to switch from .net to Objective C, take a look at Rob's post Android and iOS is quite a culture-change for Windows developers. So to give them a feel for the problems real users might have, we needed some real users - we offered our colleagues subsidised tablets. The only conditions were that they get used at work, and we get the feedback. Seeing tablets around the office is starting to give us some data points: Is typing the bottleneck? Will tablets ever cut it as text-entry devices, and could we fix it? Is mobile working held up by the pain of connecting to work LANs? How about security? Multi-tasking will let tablets do more. They're small, easy to use, almost instant to switch on, and connect by Wi Fi. There's plenty on that list to make a sysadmin twitchy. We'll find out as people spend more time working with these devices, and we'd love to hear what you think about tablet devices too. (comments are filtered, what with the spam)

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  • Problem with apt-get [install, purge, autoremove, upgrade]

    - by Ark
    I am trying to install openvpn using apt-get, but I get an error during the process [As far as I understand the issue is with unattended-updates, which I could not upgrade due to apt-get porblem :/]. I cannot upgrade, install, autoremove or purge anything else [which I need to do since /boot is full. For upgrading I did update before trying].... Trace [on sudo apt-get autoremove]: 0 upgraded, 0 newly installed, 79 to remove and 421 not upgraded. 35 not fully installed or removed. Need to get 24.1 kB of archives. After this operation, 140 MB disk space will be freed. Do you want to continue [Y/n]? y Get:1 http://us.archive.ubuntu.com/ubuntu/ oneiric/main unattended-upgrades all 0.73ubuntu1 [24.1 kB] Fetched 24.1 kB in 0s (31.2 kB/s) Preconfiguring packages ... (Reading database ... 287206 files and directories currently installed.) Removing flashplugin-downloader:i386 ... Removing libasound2-plugins:i386 ... Removing libpulse0:i386 ... Removing libsndfile1:i386 ... Removing libvorbisenc2:i386 ... Removing libvorbis0a:i386 ... Processing triggers for libc-bin ... ldconfig deferred processing now taking place (Reading database ... 287174 files and directories currently installed.) Preparing to replace unattended-upgrades 0.73ubuntu1 (using .../unattended-upgrades_0.73ubuntu1_all.deb) ... Checking for running unattended-upgrades: Traceback (most recent call last): File "/usr/share/unattended-upgrades/unattended-upgrade-shutdown", line 27, in <module> import apt_pkg ImportError: No module named apt_pkg invoke-rc.d: initscript unattended-upgrades, action "stop" failed. dpkg: warning: subprocess old pre-removal script returned error exit status 1 dpkg - trying script from the new package instead ... Checking for running unattended-upgrades: Traceback (most recent call last): File "/usr/share/unattended-upgrades/unattended-upgrade-shutdown", line 27, in <module> import apt_pkg ImportError: No module named apt_pkg invoke-rc.d: initscript unattended-upgrades, action "stop" failed. dpkg: error processing /var/cache/apt/archives/unattended-upgrades_0.73ubuntu1_all.deb (--unpack): subprocess new pre-removal script returned error exit status 1 update-rc.d: warning: unattended-upgrades start runlevel arguments (2 3 4 5) do not match LSB Default-Start values (none) update-rc.d: warning: unattended-upgrades stop runlevel arguments (0 1 6) do not match LSB Default-Stop values (0 6) Checking for running unattended-upgrades: Traceback (most recent call last): File "/usr/share/unattended-upgrades/unattended-upgrade-shutdown", line 27, in <module> import apt_pkg ImportError: No module named apt_pkg invoke-rc.d: initscript unattended-upgrades, action "start" failed. dpkg: error while cleaning up: subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: /var/cache/apt/archives/unattended-upgrades_0.73ubuntu1_all.deb E: Sub-process /usr/bin/dpkg returned an error code (1) Maybe I missed something basic, but I would appreciate pointers on solving the issue. Thanks

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  • Array Multiplication and Division

    - by Narfanator
    I came across a question that (eventually) landed me wondering about array arithmetic. I'm thinking specifically in Ruby, but I think the concepts are language independent. So, addition and subtraction are defined, in Ruby, as such: [1,6,8,3,6] + [5,6,7] == [1,6,8,3,6,5,6,7] # All the elements of the first, then all the elements of the second [1,6,8,3,6] - [5,6,7] == [1,8,3] # From the first, remove anything found in the second and array * scalar is defined: [1,2,3] * 2 == [1,2,3,1,2,3] But What, conceptually, should the following be? None of these are (as far as I can find) defined: Array x Array: [1,2,3] * [1,2,3] #=> ? Array / Scalar: [1,2,3,4,5] / 2 #=> ? Array / Scalar: [1,2,3,4,5] % 2 #=> ? Array / Array: [1,2,3,4,5] / [1,2] #=> ? Array / Array: [1,2,3,4,5] % [1,2] #=> ? I've found some mathematical descriptions of these operations for set theory, but I couldn't really follow them, and sets don't have duplicates (arrays do). Edit: Note, I do not mean vector (matrix) arithmetic, which is completely defined. Edit2: If this is the wrong stack exchange, tell me which is the right one and I'll move it. Edit 3: Add mod operators to the list. Edit 4: I figure array / scalar is derivable from array * scalar: a * b = c => a = b / c [1,2,3] * 3 = [1,2,3]+[1,2,3]+[1,2,3] = [1,2,3,1,2,3,1,2,3] => [1,2,3] = [1,2,3,1,2,3,1,2,3] / 3 Which, given that programmer's division ignore the remained and has modulus: [1,2,3,4,5] / 2 = [[1,2], [3,4]] [1,2,3,4,5] % 2 = [5] Except that these are pretty clearly non-reversible operations (not that modulus ever is), which is non-ideal. Edit: I asked a question over on Math that led me to Multisets. I think maybe extensible arrays are "multisets", but I'm not sure yet.

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  • What do you do when you encounter an idiotic interview question?

    - by Senthil
    I was interviewing with a "too proud of my java skills"-looking person. He asked me "What is your knowledge on Java IO classes.. say.. hash maps?" He asked me to write a piece of java code on paper - instantiate a class and call one of the instance's methods. When I was done, he said my program wouldn't run. After 5 minutes of serious thinking, I gave up and asked why. He said I didn't write a main function so it wouldn't run. ON PAPER. [I am too furious to continue with the stupidity...] Believe me it wasn't trick questions or a psychic or anger management evaluation thing. I can tell from his face, he was proud of these questions. That "developer" was supposed to "judge" the candidates. I can think of several things: Hit him with a chair (which I so desperately wanted to) and walk out. Simply walk out. Ridicule him saying he didn't make sense. Politely let him know that he didn't make sense and go on to try and answer the questions. Don't tell him anything, but simply go on to try and answer the questions. So far, I have tried just 4 and 5. It hasn't helped. Unfortunately many candidates seem to do the same and remain polite but this lets these kind of "developers" just keep ascending up the corporate ladder, gradually getting the capacity to pi** off more and more people. How do you handle these interviewers without bursting your veins? What is the proper way to handle this, yet maintain your reputation if other potential employers were to ever get to know what happened here? Is there anything you can do or should you even try to fix this? P.S. Let me admit that my anger has been amplified many times by the facts: He was smiling like you wouldn't believe. I got so many (20 or so) calls from that company the day before, asking me to come to the interview, that I couldn't do any work that day. I wasted a paid day off.

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  • Lubuntu: neither shut-down nor restart works

    - by Rantanplan
    aI have a freshly installed Lubuntu 14.04.1 (installed with forcepae option on a laptop with Pentium M processor). The only problem that I have found so far is that I cannot shut-down or restart the laptop. It always continues showing "Lubuntu" and some dots. Pressing Esc it says wait-for-state stop/waiting * Stopping rsync daemon rsync [OK] * Asking all remaining processes to terminate… [OK] * Killing all remaining processes… [fail] ModemManager [597] : <info> Caught signal, shutting down… ModemManager [597] : <info> ModemManager is shut down nm-dispatcher.action: Could not get the system bus. Make sure the message bus daemon is running! Message: Did not receive a reply. Possible causes: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. * Deactivating swap… [OK] * Will now halt The cursor remains blinking but the only way to switch it off is to hold the power-off key pressed for some seconds. I tried sudo shutdown -h now, sudo halt and sudo poweroff resulting in the same problem. I also tried to add acpi=force in GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" in /etc/default/grub and run sudo update-grub; then, using the taskbar's shot-down button lead to a direct stop of the laptop equal to holding the power-off key pressed for some seconds. Next I followed the answer http://askubuntu.com/a/202481/288322. Now, I directly receive some messages during shut-down starting wait-for-state stop/waiting * Stopping rsync daemon rsync [OK] * Asking all remaining processes to terminate… [OK] [ 240.944277] INFO: task kworker/0:2:24: block for more than 120 seconds. [ 240.944461] Tainted: G S 3.13.0-34-generic #60-Ubuntu [ 240.944623] "echo 0 > /proc/sys/kernel/hung_tasks_timeout_secs" disables this message. followed by some more similar lines and then: * Killing all remaining processes… [fail] ModemManager [576] : <info> Caught signal, shutting down… nm-dispatcher.action: Caught signal 15, shutting down... ModemManager [576] : <info> ModemManager is shut down * Deactivating swap… [OK] * Will now halt [ 600.944276] INFO: task kworker/0:2:24: block for more than 120 seconds. [ 600.944458] Tainted: G S 3.13.0-34-generic #60-Ubuntu [ 600.944619] "echo 0 > /proc/sys/kernel/hung_tasks_timeout_secs" disables this message. Then, nothing more was coming during the next 5 minutes. If you know where can I find relevant error information, I will be happy to search for them.

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  • Overload Avoidance

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

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  • Tips on ensuring Model Quality

    - by [email protected]
    Given enough data that represents well the domain and models that reflect exactly the decision being optimized, models usually provide good predictions that ensure lift. Nevertheless, sometimes the modeling situation is less than ideal. In this blog entry we explore the problems found in a few such situations and how to avoid them.1 - The Model does not reflect the problem you are trying to solveFor example, you may be trying to solve the problem: "What product should I recommend to this customer" but your model learns on the problem: "Given that a customer has acquired our products, what is the likelihood for each product". In this case the model you built may be too far of a proxy for the problem you are really trying to solve. What you could do in this case is try to build a model based on the result from recommendations of products to customers. If there is not enough data from actual recommendations, you could use a hybrid approach in which you would use the [bad] proxy model until the recommendation model converges.2 - Data is not predictive enoughIf the inputs are not correlated with the output then the models may be unable to provide good predictions. For example, if the input is the phase of the moon and the weather and the output is what car did the customer buy, there may be no correlations found. In this case you should see a low quality model.The solution in this case is to include more relevant inputs.3 - Not enough cases seenIf the data learned does not include enough cases, at least 200 positive examples for each output, then the quality of recommendations may be low. The obvious solution is to include more data records. If this is not possible, then it may be possible to build a model based on the characteristics of the output choices rather than the choices themselves. For example, instead of using products as output, use the product category, price and brand name, and then combine these models.4 - Output leaking into input giving the false impression of good quality modelsIf the input data in the training includes values that have changed or are available only because the output happened, then you will find some strong correlations between the input and the output, but these strong correlations do not reflect the data that you will have available at decision (prediction) time. For example, if you are building a model to predict whether a web site visitor will succeed in registering, and the input includes the variable DaysSinceRegistration, and you learn when this variable has already been set, you will probably see a big correlation between having a Zero (or one) in this variable and the fact that registration was successful.The solution is to remove these variables from the input or make sure they reflect the value as of the time of decision and not after the result is known. 

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  • Desktop Fun: Happy New Year Icon and Font Packs

    - by Asian Angel
    With the Christmas holiday so near, New Year’s Eve and Day will not be far behind. To help you prepare those New Year’s Eve and Day celebrations we have put together a nice collection of fonts for party invitations, fliers, decorations, and more. We also have icon goodness to make your desktop all bright and shiny for the new year. Sneak Preview This is the New Year’s desktop that we put together using the Birthday Icon Set shown below. Note: The original unmodified version of this wallpaper can be found here. An up close look at the icons that we used… The Icon Packs Note: To customize the icon setup on your Windows 7 & Vista systems see our article here. Using Windows XP? We have you covered here. New Year Celebration Icon Set *.ico format only Download New Year Party Icon *.ico, .png, and .icns format Note: This icon is available for download in single file format (based on format type and/or image size). Download Celebration *.ico format only Download Birthday *.ico, .png, and .icns format Special Note: While not an official New Year’s set of icons, it will still work nicely for a New Year’s or celebration desktop setup. Download The Font Packs Note: To manage the fonts on your Windows 7, Vista, & XP systems see our article here. Cocktail Bubbly Download Fontdinerdotcom Sparkly Download Confetti Download KR Happy New Year 2002 Note: For those who are curious about this font’s shape, it is a cork popping out of a champagne bottle. Download NewYearBats *includes 52 individual characters Note: This group represents A – Z in all capital letters. Note: This group represents A – Z in all lower case letters. Download LCR Party Dings *includes 26 individual characters (A – Z), not case sensitive Special Note: This font is an all-purpose type that covers a variety of party/celebration types from New Year’s to birthdays. Download For more great ways to customize your computer be certain to look through our Desktop Fun section. Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Track Weather Conditions with the Weather Underground Web App for Chrome These 8-Bit Mario Wood Magnets Put Video Games on Your Fridge Christmas Themes 4 Pack for Chrome and Iron Browser Enjoy the First Total Lunar Eclipse in 372 Years This Evening Gmail’s Free Calling Extended Through 2011 Voice Search Brings Android-Style Voice Search to Google Chrome

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  • How to refactor a Python “god class”?

    - by Zearin
    Problem I’m working on a Python project whose main class is a bit “God Object”. There are so friggin’ many attributes and methods! I want to refactor the class. So Far… For the first step, I want to do something relatively simple; but when I tried the most straightforward approach, it broke some tests and existing examples. Basically, the class has a loooong list of attributes—but I can clearly look over them and think, “These 5 attributes are related…These 8 are also related…and then there’s the rest.” getattr I basically just wanted to group the related attributes into a dict-like helper class. I had a feeling __getattr__ would be ideal for the job. So I moved the attributes to a separate class, and, sure enough, __getattr__ worked its magic perfectly well… At first. But then I tried running one of the examples. The example subclass tries to set one of these attributes directly (at the class level). But since the attribute was no longer “physically located” in the parent class, I got an error saying that the attribute did not exist. @property I then read up about the @property decorator. But then I also read that it creates problems for subclasses that want to do self.x = blah when x is a property of the parent class. Desired Have all client code continue to work using self.whatever, even if the parent’s whatever property is not “physically located” in the class (or instance) itself. Group related attributes into dict-like containers. Reduce the extreme noisiness of the code in the main class. For example, I don’t simply want to change this: larry = 2 curly = 'abcd' moe = self.doh() Into this: larry = something_else('larry') curly = something_else('curly') moe = yet_another_thing.moe() …because that’s still noisy. Although that successfully makes a simply attribute into something that can manage the data, the original had 3 variables and the tweaked version still has 3 variables. However, I would be fine with something like this: stooges = Stooges() And if a lookup for self.larry fails, something would check stooges and see if larry is there. (But it must also work if a subclass tries to do larry = 'blah' at the class level.) Summary Want to replace related groups of attributes in a parent class with a single attribute that stores all the data elsewhere Want to work with existing client code that uses (e.g.) larry = 'blah' at the class level Want to continue to allow subclasses to extend, override, and modify these refactored attributes without knowing anything has changed Is this possible? Or am I barking up the wrong tree?

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  • Ed Burns' Servlet 4/HTTP 2 Session at JavaOne

    - by Yolande Poirier
    By Guest Blogger Reza Rahman For the Java EE track at JavaOne 2014 we are highlighting some key sessions and speakers to better inform you of what you can expect, right up until the start of the conference. To this end we recently interviewed Ed Burns. Ed is a veteran of Sun and now Oracle. He has been and is instrumental in pushing the JSF ecosystem forward as specification lead. Besides his specification lead work Ed is well regarded as an author and speaker on his own right. In addition to carrying the JSF torch Ed will be co-leading the key Servlet 4 specification for Java EE 8, along with Servlet specification guru Shing Wai Chan. The primary goal of Servlet 4 is to enable the fundamentally important changes in HTTP 2 for the entire server-side Java ecosystem. We wanted to talk to Ed about his Servlet 4 session at JavaOne 2014 and HTTP 2 generally: The details for the Servlet 4 session can be found here. Ed has several other key sessions on the track that we hope to talk to him about separately in the near future: What’s Next for JSF?: In this key session, Ed will be sharing the next steps for the continued evolution of the JSF specification in Java EE 8. Where’s My UI? The 2014 JavaOne Web App UI Smackdown: The UI space for web applications, especially in the Java ecosystem continues to be as hotly contested as ever. This is especially true with the (re)introduction of JavaScript based rich client frameworks like AngularJS. This lively panel brings together experts representing the diverse schools of thought for web UIs. Ed will be representing JSF of course. Neal Ford will moderate the panel as an independent and hopefully reasonably neutral party. Adopt-a-JSR for Java EE 7 and Java EE 8: Adopt-a-JSR has been a reasonable success for Java EE 7. With Java EE 8 we are planning to strengthen it far more as away of getting grassroots level participation in the specification efforts. This session will introduce Adopt-a-JSR, share how it worked for Java EE 7 and what we plan to do with it in Java EE 8. Ed will be sharing his perspectives on Adopt-a-JSR for both Java EE 7 and Java EE 8. Besides Ed's sessions, we have a very strong program for the Java EE track and JavaOne overall - just explore the content catalog. If you can't make it, you can be assured that we will make key content available after the conference just as we have always done.

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