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Articles indexed in March 2012

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  • How do I organize C# classes that inherit from one another, but also have properties that inherit from one another?

    - by Chris
    I have an application that has a concept of a Venue, a place where events happen. A Venue is owned by a Company and has many VenueParts. So, it looks like this: public abstract class Venue { public int Id { get; set; } public string Name { get; set; } public virtual Company Company { get; set; } public virtual ICollection<VenuePart> VenueParts { get; set; } } A Venue can be a GolfCourseVenue, which is a Venue that has a Slope and a specific kind of VenuePart called a HoleVenuePart: public class GolfCourseVenue { public string Slope { get; set; } public virtual ICollection<HoleVenuePart> Holes { get; set; } } In the future, there may also be other kinds of Venues that all inherit from Venue. They might add their own fields, and will always have VenueParts of their own specific type. My declarations above seem wrong, because now I have a GolfCourseVenue with two collections, when really it should just have the one. I can't override it, because the type is different, right? When I run reports, I would like to refer to the classes generically, where I just spit out Venues and VenueParts. But, when I render forms and such, I would like to be specific. I have a lot of relationships like this and am wondering what I am doing wrong. For example, I have an Order that has OrderItems, but also specific kinds of Orders that have specific kinds of OrderItems.

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  • Imports and Depends

    - by David Diez
    I have read two recent posts that discuss Depends and Imports but I have four lingering, related questions: Suppose I want two packages to also be available to the end-user when they load in my package. Is there a good reason not to use Depends in this context? (The point here is to load all three packages via a command that loads just the one package.) Is it okay to specify a package in both the Depends and Imports fields? If a package is listed in Depends, is there a point to also listing it in Imports? Or are the benefits of Imports already negated by using Depends? [Added Question] Is the following correct? A package should be listed in the Imports field of the DESCRIPTION file if and only if the package is imported (in whole or in part) in the NAMESPACE file. Thanks much! David

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  • C# Linq: Restructuring object

    - by Ben
    I'd like to take an object like this: SortedList<string, SortedList<int, SortedList<DateTime, double>>> Data and, for a given 'int' value (key of first nested sorted list), restructure it like this: SortedList<DateTime, SortedList<string, double>> or, better yet, this: SortedList<DateTime, double[]> where each 'double[]' has as many elements as there are KeyValue pairs in the SortedList. I'm guessing Linq is the way to go, but can't figure it out. Thanks for any suggestions.

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  • Is unnecessary error handling recommended in business logic? eg. Null check/Percentage limit check etc

    - by novice_at_work
    We usually put unnecessary checks in our business logic to avoid failures. Eg. 1. public ObjectABC funcABC(){ ObjectABC obj = new ObjectABC; .......... .......... //its never set to null here. .......... return obj; } ObjectABC o = funABC(); if(o!=null){ //do something } Why do we need this null check if we are sure that it will never be null? Is it a good practice or not? 2. int pplReached = funA(..,..,..); int totalPpl = funB(..,..,..); funA() just puts a few more restriction over result of funB(). Double percentage = (totalPpl==0||totalPpl<pplReached) ? 0.0 : pplReached/totalPpl; Do we again need this check? The questions is: Aren't we swallowing some fundamental issue by putting such checks? Issues which should be shown ideally, are avoided by putting these checks. What is the recommended way?

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  • Sudden issues reading uncompressed video using opencv

    - by JohnSavage
    I have been using a particular pipeline to process video using opencv to encode uncompressed video (fourcc = 0), and opencv python bindings to then open and work on these files. This has been working fine for me on OpenCV 2.3.1a on Ubuntu 11.10 until just a few days ago. For some reason it currently is only allowing me to read the first frame of a given file the first time I open that file. Further frames are not read, and once I touch the file once with my program, it then cannot even read the first frame. More detail: I created the uncompressed video files as follows: out_video.open(out_vid_name, 0, // FOURCC = 0 means record raw fps, Size(640, 480)) Again, these videos worked fine for me until about a week ago. Now, when I try to open one of these I get the following message (from what I think is ffmpeg): Processing video.avi Using network protocols without global network initialization. Please use avformat_network_init(), this will become mandatory later. [avi @ 0x29251e0] parser not found for codec rawvideo, packets or times may be invalid. It reads and displays the first frame fine, but then fails to read the next frame. Then, when I try to run my code on the same video, the capture still opens with the same message as above. However, it cannot even read the very first frame. Here is the code to open the capture: self.capture = cv2.VideoCapture(filename) if not self.capture.isOpened() print "Error: could not open capture" sys.exit() Again, this part is passed without any issue, but then the break happens at: success, rgb = self.capture.read() if not success: print "error: could not read frame" return False This part breaks at the second frame on the first run of the video file, and then on the first frame on subsequent runs. I really don't know where to even begin debugging this. Please help!

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  • UrlRewriteFilter Direct to https

    - by adi
    I am using UrlRewriteFilter to redirect to SSL. I am running Glassfishv2. My rule looks something like this now. It's in my urlrewrite.xml in WEB-INF of my war folder. Is there any other glassfish setting that needs to be set? <rule> <condition name="host" operator="notequal">https://abc.def.com</condition> <condition name="host" operator="notequal">^$</condition> <from>^/(.*)</from> <to type="permanent-redirect" last="true">https://abc.def.com/ghi/$1</to> </rule> But FF keeps saying that the URL redirect rule is in a way that it will never complete. I am not exactly sure whats happening here. any ideas?

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  • LINQ, creating unique collection of a collection

    - by Wish
    I have class Vertex and a class Edge (Edge holds 2 properties - Vertex Source and Vertex Target); Edges and Vertexes are collected into lists Some example: A-->B // edge from vertex A to B B-->C // edge from vertex B to C C-->A // edge from vertex C to A A-->C // edge from vertex A to C -- this is two way edge So I would like to make IDictionary<Edge, bool> which would hold edges (A--B and B--A would be like 1), and bool - if it is two way or no. I need it because when I draw them now, it draws 2 arrows under one another. I would better make 1 arrow. So I'm pretty stuck right here... May anybody help me a bit ?

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  • Html5 - Callback when media is ready on iPad wont work

    - by Kap
    I'm trying to add a callback to a HTML5 audio element on an iPad. I added an eventlistener to the element, the myOtherThing() starts but there is no sound. If I pause and the play the sound again the audio starts. This works in chrome. Does anyone have an idea how I can do this? myAudioElement.src = "path_to_file"; addEventListener("canplay", function(){ myAudioElement.play(); myOtherThing.start(); }); SOLVED Just wanted to share my solution here, just in case someone else needs it. As far as I understand the iPad does not trigger any events without user interactions. So to be able to use "canply", "playing" and all the other events you need to use the built in media controller. Once you press play in that controller, the events gets triggered. After that you can use your custom interface.

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  • Inverse relationship of two variables

    - by Jam
    this one is maybe pretty stupid.. Or I am just exhausted or something, but I just cant seem to solve it.. Problem : two variables X and Y, value of Y is dependent on value of X. X can have values ranging from some value to some value (lets say from 0 to 250) and y can have different values (lets say from 0.1 to 1.0 or something..) - but it is inverse relatonship (what I mean is: if value of X is e.g. 250, then value of Y would be 0.1 and when X decreases up to 0, value of Y raises up to 1.0.. So how should I do it? lets say I have function: -- double computeValue (double X) { /computation/ return Y; } Also, is there some easy way to somehow make the scaling of the function not so linear? - For example when X raises, Y decreases slower at first but then more rapidly in the end.. (rly dont know how to say it but I hope you guys got it) Thanks in advance for this stupid question :/

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  • Replace token in ANTLR

    - by user1019710
    I want to replace a token using ANTLR. I tried with TokenRewriteStream and replace, but it didn't work. Any suggestions? ANTLRStringStream in = new ANTLRStringStream(source); MyLexer lexer = new MyLexer(in); TokenRewriteStream tokens = new TokenRewriteStream(lexer); for(Object obj : tokens.getTokens()) { CommonToken token = (CommonToken)obj; tokens.replace(token, "replacement"); } The lexer finds all occurences of single-line comments, and i want to replace them in the original source too.

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  • symfony 1.4 embedForm not returning all embedded forms

    - by Patrick
    I have a form with multiple embedded forms and symfony is not binding all the embedded forms. The layout is a m-to-m layout: activity: id: link: id: activity_id: FOREIGN KEY to activity table other_data_id: FOREIGN KEY to other_data table other_data: id: For instance I have 7 identical embedded forms iterated at the end of each name (ie- form_1, form_2, ..., form_7). With the new and edit forms all the 7 fields display properly, but when I submit the form, the embedded forms after a certain number just aren't in the embedded forms array of the sfForm. I have two different embedded forms, the first form stops binding at 5 and the second form stops binding at 4. I've looked at the array of posted values through $request->getPostParameters(); and all the fields are there. If I manually enter the data into the database, the binding works without a problem. Any ideas would be greatly appreciated!

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  • drawing to a JPanel without inheritance

    - by g.rocket
    Right now I'm working on a program that throws up a bunch of separate (generated at runtime) images, each in their own window. To do this i've tried this approach: public void display(){ JFrame window = new JFrame("NetPart"); JPanel canvas = new JPanel(); window.getContentPane().add(canvas); Graphics g = canvas.getGraphics(); Dimension d = getSize(); System.out.println(d); draw(g,new Point(d.minX*50,d.maxY*50), 50); window.setSize(d.size(50)); window.setResizable(false); window.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE); window.setVisible(true); } public void draw(Graphics g, Point startLoc, int scale){ // generate and draw the image } public Dimension getSize(){ //returns my own dimensions class } However, this throws a NullPointerException in draw, claiming that the graphics is null. is there any way to externally draw to a JPanel from outside it (not inherit from JPanel and override PaintComponent)? Any help would be appreciated.

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  • Categorize the approximate shape of an array of Points in 3D Space

    - by user1295133
    I have a set of points in 3d space and I want to be able to categorize the shape that best fits them - cube, sphere, cylinder, planar (flat) etc. I've looked at supervised/machine learning but since I need first generate a large training data set that's not really suitable. My dream solution would be a java library with a wonderful magical function something like : public enum ShapeType { CUBE, SPHERE, CYLINDER, PLANAR } public ShapeType CategorizeShapeFromPoints( 3DPoint[] points ) However, any and all help will be appreciated. Thanks

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  • What is the basic design idea behind the Scala for-loop implicit box/unboxing of numerical types?

    - by IODEV
    I'm trying to understand the behavior of Scala for-loop implicit box/unboxing of "numerical" types. Why does the two first fail but not the rest? 1) Fails: scala for (i:Long <- 0 to 10000000L) {} <console>:19: error: type mismatch;<br> found : Long(10000000L) required: Int for (i:Long <- 0 to 10000000L) {} ^ 2 Fails: scala for (i <- 0 to 10000000L) {} <console>:19: error: type mismatch; found : Long(10000000L) required: Int for (i <- 0 to 10000000L) {} ^ 3) Works: scala for (i:Long <- 0L to 10000000L) {} 4) Works: scala for (i <- 0L to 10000000L) {}

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  • make a default password for password textboxes that can't be reproduced by the client

    - by user420667
    Is it possible to set a password textbox text to text that the user could not reproduce on their end? Like are there special characters that can only be set from the server? For instance, one way to do this would be to use javascript to prevent typing of *'s, and to set the textbox text to be all *'s. But that's hacky. The motivation is to be able to tell on the server if the user changed the password at all, but not to restrict them from having a password of all *'s, for instance.

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  • creating a .sh file programmatically under windows and running it on a linux system from cygwin

    - by user1296193
    i want to write program, in windows, which will write a .sh file, then connect to a linux machine via cygwin and ssh, and execute that .sh file. I've had to use dos2unix to convert .sh files that I created in windows to run under linux. Obviously if I am executing a script with ssh it will have to be linux formatted to work. so I need to know how to create a linux appropriate .sh file using c or openoffice basic or vBA. thanks!

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  • Efficient algorithm for finding largest eigenpair of small general complex matrix

    - by mklassen
    I am looking for an efficient algorithm to find the largest eigenpair of a small, general (non-square, non-sparse, non-symmetric), complex matrix, A, of size m x n. By small I mean m and n is typically between 4 and 64 and usually around 16, but with m not equal to n. This problem is straight forward to solve with the general LAPACK SVD algorithms, i.e. gesvd or gesdd. However, as I am solving millions of these problems and only require the largest eigenpair, I am looking for a more efficient algorithm. Additionally, in my application the eigenvectors will generally be similar for all cases. This lead me to investigate Arnoldi iteration based methods, but I have neither found a good library nor algorithm that applies to my small general complex matrix. Is there an appropriate algorithm and/or library?

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  • Issues with dynamic <title> in PHP

    - by dotman14
    I have the code below: <?php $title = "Result Computation" ; ?> <title> <?php echo $title ; ?> </title> I'm using includes to call the header on all the pages, but what i want to do is that on every page i want to make it generate a specific title. On each page i've added $title = "Page Title" ; So that when the page loads it gets the title from the $title i've set on that page, but it the pages keep getting the default Title. Please how do i solve this? Thanks for your time.

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  • Decoding a jpg in the background in WP7

    - by Shahar Prish
    I have a bunch of apps in the marketplace, and so far I have been able, by changing my functionality or going the extra mile, to work around the issue of being unable to decode a jpg in the background into a WriteableBitmap. I am finding a situation where I can't think of good ways to "work around" the issue. I need to decode the image I get from MediaLibrary, reduce it's resolution to something managable (800x800), rotate it potentially and save to local storage. By far, the thing that takes the most time (80%) is decoding the bitmap to 800x800 - it takes between 700ms to 1000 ms. A user may add 7-10 images when starting, which translates to ~10 seconds of waiting for the images being added. I tried doing this lazily, but at some point you need to pay the piper and the app essentially stutters for ~1000ms at that point and the experience is not great. Is there an alternative I am missing for loading the image in the background somehow? (Note on why CreateOptions.BackgroundCreation is no good for me: It loads the image into a BitmapImage which is great if you want to just use it, but not so great for what I need to do which is create a copy in Isolated Storage).

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  • Same session and session ID for different subdomains in Grails project - How can I do that?

    - by fluxon
    I am currently working on a project that supports multiple languages. In order to be seo friendly, I am trying to redirect users subdomains corresponding to their locale (or their preferred language). I.e., my projects's url is mydomain.com and I work with the subdomains en.mydomain.com, es.mydomain.com, de.mydomain.com, fr.mydomain.com ... you get the idea. All subdomains are served by the same grails app for now. What happens is that my grails project maintains different sessions (as seen by the session ids) for every single subdomain, hence information is lost, when a user switches between languages. I had not forseen that. :( How can I explicitly set the session identifier? I would like it to be based on just mydomain.com. I got the hint that Apache Tomcat offers something like <Context sessionCookiePath="/" sessionCookieDomain=".mydomain.com"> , but that does not help for the devel environment etc. Any hints? Have you tried storing session information in the DB? This is sometimes used for load-balancing purposes and might help here as well?! Help is highly appreciated (as always)! Cheers!

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  • rendering front-end of survey into an MVC app

    - by HotKey
    Lately I have been watching Pluralsight intro videos on MVC 3. I have never worked with the Model View Control approach before, but I'm starting to understand how these 3 crucial parts of an app are separated. I created a front-end prototype of a survey I would like to implement into a View of my MVC web app. The survey is in HTML, CSS, using jQuery to deliver content changes depending on the type of evaluation (6-11 questions), and jQuery UI for a couple slider ratings. I noticed through tutorials that you can use an HTML form and helpers that allow the user to edit content, but my prototype already allows the users to rate via radio buttons, comment text boxes, and sliders. Would I need to change any of my existing code if I just want to store this employee data to the Model, and depending on what survey's the employee has completed through the Controller, disable drop down fields? Also, would I store the current employee data on submit of survey through an HttpPost in the Controller to the Model? My apologies if my questions seem rather vague. Could someone point me in the right direction to a resource or documentation similar to my needs above? The Pluralsight videos are taking me in the wrong direction.

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  • What’s new in IIS8, Perf, Indexing Service-Week 49

    - by OWScott
    You can find this week’s video here. After some delays in the publishing process week 49 is finally live.  This week I'm taking Q&A from viewers, starting with what's new in IIS8, a question on enable32BitAppOnWin64, performance settings for asp.net, the ARR Helper, and Indexing Services. Starting this week for the remaining four weeks of the 52 week series I'll be taking questions and answers from the viewers. Already a number of questions have come in. This week we look at five topics. Pre-topic: We take a look at the new features in IIS8. Last week Internet Information Services (IIS) 8 Beta was released to the public. This week's video touches on the upcoming features in the next version of IIS. Here’s a link to the blog post which was mentioned in the video Question 1: In a number of places (http://learn.iis.net/page.aspx/201/32-bit-mode-worker-processes/, http://channel9.msdn.com/Events/MIX/MIX08/T06), I've saw that enable32BitAppOnWin64 is recommended for performance reasons. I'm guessing it has to do with memory usage... but I never could find detailed explanation on why this is recommended (even Microsoft books are vague on this topic - they just say - do it, but provide no reason why it should be done). Do you have any insight into this? (Predrag Tomasevic) Question 2: Do you have any recommendations on modifying aspnet.config and machine.config to deliver better performance when it comes to "high number of concurrent connections"? I've implemented recommendations for modifying machine.config from this article (http://www.codeproject.com/KB/aspnet/10ASPNetPerformance.aspx - ASP.NET Process Configuration Optimization section)... but I would gladly listen to more recommendations if you have them. (Predrag Tomasevic) Question 3: Could you share more of your experience with ARR Helper? I'm specifically interested in configuring ARR Helper (for example - how to only accept only X-Forwards-For from certain IPs (proxies you trust)). (Predrag Tomasevic) Question 4: What is the replacement for indexing service to use in coding web search pages on a Windows 2008R2 server? (Susan Williams) Here’s the link that was mentioned: http://technet.microsoft.com/en-us/library/ee692804.aspx This is now week 49 of a 52 week series for the web pro. You can view past and future weeks here: http://dotnetslackers.com/projects/LearnIIS7/ You can find this week’s video here.

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  • Mail on other server

    - by takeshin
    Here is the current DNS setup: mx.example.com 3600 A 93.157.123.73 example.com 3600 A 93.157.123.93 www.example.com 3600 A 93.157.123.93 mail.example.com 3600 A 93.157.123.72 smtp.example.com 3600 CNAME mail.example.com pop3.example.com 3600 CNAME mail.example.com imap.example.com 3600 CNAME mail.example.com panel.example.com 3600 CNAME panel.example2.pl www.panel.example.com 3600 CNAME panel.example2.pl ftp.example.com 3600 CNAME example.com mysql.example.com 3600 CNAME example.com pgsql.example.com 3600 CNAME example.com *.example.com 3600 CNAME example.com example.com 3600 MX 10 mx.example.com example.com 3600 NS ns1.example2.pl example.com 3600 NS ns2.example.pl example.com 3600 TXT "v=spf1 redirect=_spf.example3.pl" My client wants to have mail on his own server alfa.otherhost.com. Which entries do I have to update? Only the MX one? example.com 3600 MX 10 alfa.otherhost.com or: example.com 3600 MX 10 mx.alfa.otherhost.com Do I need to update POP, SMTP and IMAP entries too?

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  • Solaris 10 opencsw git package issue with bitbucket git hosting

    - by zephyrus00jp
    Has anyone tried using `git' from opencsw package in order to work with bitbucket source hosting service (under solaris10)? I tried to use git as the bitbucket documentation explains, and - under Debian GNU/Linux, it worked flawlessly as described, but - under Solaris 10, I got Authentication Failed message. I even tried to run truss to see anything is suspicious but could not find any smoking gun under solaris why it failed. ldd git-binary didnd't show anything suspicious either (except for the libcrypt library which could be a suspicious to think about export restrictions. Have they shipped incompatible version? BUT since the password is typed into https: connection, I suspect it is only a matter of web-level cryptography and should be universal these days.) I am now tempted to compile git suite under solaris 10, but I did find people who seem to be using git with bitbucket under solaris 10 and am wondering what could be wrong.

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  • Multicasting Windows 7 Image

    - by LawnChairSkank
    I am trying to deploy some new machines with windows 7 for the first time in our computer labs. We used to use third party imaging software and then run sysprep after the image was copied(XP), but it seems you can't go that route with windows 7. We set up a new imaging server with the windows system image manager, but when we try to multicast the image it pretty much takes down our whole staff and faculty network. I heard you can turn on a multicast feature on our cisco switches to help with the issue, but that it also slows the switches to a crawl. Another idea we have tried was pulling the the computer lab switch off the main network and plugging the imaging server directly into the computer lab switch so the multicast doesn't take down our network, but it doesn't seem to work without being able to hit a domain controller. Is there a way to multicast without taking out the network? I feel like I am missing something... Thanks in advance

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