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  • GOTO still considered harmful?

    - by Kyle Cronin
    Everyone is aware of Dijkstra's Letters to the editor: go to statement considered harmful (also here .html transcript and here .pdf) and there has been a formidable push since that time to eschew the goto statement whenever possible. While it's possible to use goto to produce unmaintainable, sprawling code, it nevertheless remains in modern programming languages. Even the advanced continuation control structure in Scheme can be described as a sophisticated goto. What circumstances warrant the use of goto? When is it best to avoid? As a followup question: C provides a pair of functions, setjmp and longjmp, that provide the ability to goto not just within the current stack frame but within any of the calling frames. Should these be considered as dangerous as goto? More dangerous? Dijkstra himself regretted that title, of which he was not responsible for. At the end of EWD1308 (also here .pdf) he wrote: Finally a short story for the record. In 1968, the Communications of the ACM published a text of mine under the title "The goto statement considered harmful", which in later years would be most frequently referenced, regrettably, however, often by authors who had seen no more of it than its title, which became a cornerstone of my fame by becoming a template: we would see all sorts of articles under the title "X considered harmful" for almost any X, including one titled "Dijkstra considered harmful". But what had happened? I had submitted a paper under the title "A case against the goto statement", which, in order to speed up its publication, the editor had changed into a "letter to the Editor", and in the process he had given it a new title of his own invention! The editor was Niklaus Wirth. A well thought out classic paper about this topic, to be matched to that of Dijkstra, is Structured Programming with go to Statements (also here .pdf), by Donald E. Knuth. Reading both helps to reestablish context and a non-dogmatic understanding of the subject. In this paper, Dijkstra's opinion on this case is reported and is even more strong: Donald E. Knuth: I believe that by presenting such a view I am not in fact disagreeing sharply with Dijkstra's ideas, since he recently wrote the following: "Please don't fall into the trap of believing that I am terribly dogmatical about [the go to statement]. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline!"

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  • TraceRoute and Ping in C#

    - by NET789
    Does anyone have C# code handy for doing a ping and traceroute to a target computer? I am looking for a pure code solution, not what I'm doing now, which is invoking the ping.exe and tracert.exe program and parsing the output. I would like something more robust.

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  • UITableViewCell with selectable/copyable text that also detects URLs on the iPhone

    - by Jasarien
    Hi guys, I have a problem. Part of my app requires text to be shown in a table. The text needs to be selectable/copyable (but not editable) and any URLs within the text need to be highlighted and and when tapped allow me to take that URL and open my embedded browser. I have seen a couple of solutions that solve one of either of these problems, but not both. Solution 1: Icon Factory's IFTweetLabel The first solution I tried was to use the IFTweetLabel class made possible by Icon Factory and used in Twitterrific. While this solution allows for links (or anything you can find with a regex) to be detected to be handled on a case by case basis, it doesn't allow for selecting and copying. There is also an issue where if a URL is long enough to be wrapped, the button that the class overlays above the URL to make it interactive cannot wrap and draws off screen, looking very odd. Solution 2: Use IFTweetLabel and handle copy manually The second thing I tried was to keep IFTweetLabel in place to handle the links, but to implement the copying using a long-tap gesture, like how the SMS app handles it. This was just about working, but it doesn't allow for arbitrary selection of text, the whole text is copied, or none is copied at all... Pretty black and white. Solution 3: UITextView My third attempt was to add a UITextView as a subview of the table cell. The only thing that this doesn't solve is the fact that detected URLs cannot be handled by me. The text view uses UIApplication's openURL: method which quits my app and launched Safari. Also, as the table view can get quite large, the number of UITextViews added as subviews cause a noticeable performance drag on scrolling throughout the table, especially on iPhone 3G era devices (because of the creation, layout, compositing whenever a cell is scrolled on screen, etc). So my question to all you knowledgeable folk out there is: What can I do? Would a UIWebView be the best option? Aside from a performance drag, I think a webview would solve all the above issues, and if I remember correctly, back in the 2.0 days, the Apple documentation actually recommended web views where text formatting / hyperlinks were required. Can anyone think of a way to achieve this without a performance drag? Many thanks in advance to everyone who can help.

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  • C stack/scope, variable's lifetime after functions ends

    - by Ranking Stackingblocks
    void someFunc() { int stackInt = 4; someOtherFunc(&stackInt); } Is it the case that stackInt's address space could be reallocated after someFunc ends, making it unsafe to assume that the value passed to someOtherFunc represents the stackInt variable with value 4 that was passed to it? In other words, should I avoid passing stack variables around by address and expecting them to still be alive after the function they were initialised in has ended?

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  • NoHostAvailableException With Cassandra & DataStax Java Driver If Large ResultSet

    - by hughj
    The setup: 2-node Cassandra 1.2.6 cluster replicas=2 very large CQL3 table with no secondary index Rowkey is a UUID.randomUUID().toString() read consistency set to ONE Using DataStax java driver 1.0 The request: Attempting to do a table scan by "SELECT some-col from schema.table LIMIT nnn;" The fail: Once I go beyond a certain nnn LIMIT, I start to get NoHostAvailableExceptions from the driver. It reads like this: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:64) at com.datastax.driver.core.ResultSetFuture.extractCauseFromExecutionException(ResultSetFuture.java:214) at com.datastax.driver.core.ResultSetFuture.getUninterruptibly(ResultSetFuture.java:169) at com.jpmc.es.rtm.storage.impl.EventExtract.main(EventExtract.java:36) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:98) at com.datastax.driver.core.RequestHandler$1.run(RequestHandler.java:165) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) Given: This is probably not the most enlightened thing to do to a large table with millions of rows, but this is how I learn what not to do, so I would really appreciate someone who could volunteer how this kind of error can be debugged. For example, when this happens, there are no indications that the nodes in the cluster ever had an issue with the request (there is nothing in the logs on either node that indicate any timeout or failure). Also, I enabled the trace on the driver, which gives you some nice autotrace (ala Oracle) info as long as the query succeeds. But in this case, the driver blows a NoHostAvailableException and no ExecutionInfo is available, so tracing has not provided any benefit in this case. I also find it interesting that this does not seem to be recorded as a timeout (my JMX consoles tell me no timeouts have occurred). So, I am left not understanding WHERE the failure is actually occurring. I am left with the idea that it is the driver that is having a problem, but I don't know how to debug it (and I would really like to). I have read several posts from folks that state that query'g for resultSets 10000 rows is probably not a good idea, and I am willing to accept this, but I would like to understand what is causing the exception and where the exception is happening. FWIW, I also tried bumping the timeout properties in the cassandra.yaml, but this made no difference whatsoever. I welcome any suggestions, anecdotes, insults, or monetary contributions for my registration in the house of moron-developers. Regards!!

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  • Navbar List Items Not Showing in Internet Explorer 6

    - by Theo
    Hi everyone, I have a bit of a problem with a navbar not displaying correctly in IE6. http://classicpartsltd.com/ - this is the page, and if you hover over a nav item such as 'Goggles' in IE6 you will see that some of the list items are showing up, but that they will in IE7 and IE8... Does anyone know why this would be the case? Many thanks, Theo.

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  • What development technologies or technology stack is typically used in the security industry?

    - by vfilby
    In this case security means building security (access control, alarm systems, etc). And I am not talking about working directly with the hardware, more focused on web based applications/api's that clients or companies can use? Are there technologies that are commonly used? Are there technologies that shouldn't be used? Are there any real benefits to a linux based stack as opposed to a windows based stack for exposing web based applications?

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  • javascript regex validation

    - by Arun
    Is there any way to find which input character fails the regex pattern. For ex: consider [A-Za-z\s.&] is only allowable but the user enter like "test/string" where '/' invalidates input. How to find who fails regex (our case '/')

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  • Grails- Unique constraint

    - by WaZ
    How can I basically carry out a unique constraint on a string data-type field. class User{ String username String Email static hasMany = [roles:Roles] static constraints = { Email(email:true) username(unique:true) } Is there any simple way to implement username(unique:true) or I will have to manually check the database by the in-built methods like .findByNameLike. My need is that username should be unique and should be case insensitive

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  • Encrypt parameters passed to a swf

    - by 23tux
    Hi, does anyone know how to encrypt the parameters that are passed to a flash movie? The case is, that the user should not be able to read the parameters in the source code in plaintext. And of course, I have to able to decrypt the parameter in actionscript 3 ;-) thx, tux

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  • Is currying just a way to avoid inheritance?

    - by Alex Mcp
    So my understanding of currying (based on SO questions) is that it lets you partially set parameters of a function and return a "truncated" function as a result. If you have a big hairy function takes 10 parameters and looks like function (location, type, gender, jumpShot%, SSN, vegetarian, salary) { //weird stuff } and you want a "subset" function that will let you deal with presets for all but the jumpShot%, shouldn't you just break out a class that inherits from the original function? I suppose what I'm looking for is a use case for this pattern. Thanks!

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  • Track Data Execution Prevention (DEP) problem.

    - by Nicolas
    Hi, When running one of our software, a tester was faced with the data execution prevention dialog of Windows. We try to reproduce this situation on a developer computer for debugging purposes : with no success. Does anyone know how to find what may cause the DEP protection to kill the application? Is there any existing tools available for this? Any advices are welcome, Thanks, Nic

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  • ASP.NET MVC redirect from asynchronous call

    - by Idsa
    I send asynchronous call using jQuery form plugin and in the case of success want to redirect user to some "success-page". Now my ASP.NET MVC action just returns some special "success-JSON" and the user is redirected using Javascript. Is there any way to implement automatic redirect (without Javascript call)?

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  • Getting rails application from github to debian server

    - by Micke
    Hello. I've been developing my first rails application on my windows computer. But now i have been setting up a debian server with nginx and passanger. I've been using Github to keep track of my application and now i am wondering how i can get the Github version of my application to the debian server and put it in production mode? Anybody that have a good guide about this or something?

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  • Why does this thumbnail generation code throw OutOfMemoryException on large files?

    - by tsilb
    This code works great for generating thumbnails, but when given a very large (100MB+) TIFF file, it throws OutOfMemoryExceptions. When I do it manually in Paint.NET on the same machine, it works fine. How can I improve this code to stop throwing on very large files? In this case I'm loading a 721MB TIF on a machine with 8GB RAM. The Task Manager shows 2GB used so something is preventing it from using all that memory. Specifically it throws when I load the Image to calculate the size of the original. What gives? /// <summary>Creates a thumbnail of a given image.</summary> /// <param name="inFile">Fully qualified path to file to create a thumbnail of</param> /// <param name="outFile">Fully qualified path to created thumbnail</param> /// <param name="x">Width of thumbnail</param> /// <returns>flag; result = is success</returns> public static bool CreateThumbnail(string inFile, string outFile, int x) { // Validation - assume 16x16 icon is smallest useful size. Smaller than that is just not going to do us any good anyway. I consider that an "Exceptional" case. if (string.IsNullOrEmpty(inFile)) throw new ArgumentNullException("inFile"); if (string.IsNullOrEmpty(outFile)) throw new ArgumentNullException("outFile"); if (x < 16) throw new ArgumentOutOfRangeException("x"); if (!File.Exists(inFile)) throw new ArgumentOutOfRangeException("inFile", "File does not exist: " + inFile); // Mathematically determine Y dimension int y; using (Image img = Image.FromFile(inFile)) { // OutOfMemoryException double xyRatio = (double)x / (double)img.Width; y = (int)((double)img.Height * xyRatio); } // All this crap could have easily been Image.Save(filename, x, y)... but nooooo.... using (Bitmap bmp = new Bitmap(inFile)) using (Bitmap thumb = new Bitmap((Image)bmp, new Size(x, y))) using (Graphics g = Graphics.FromImage(thumb)) { g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; System.Drawing.Imaging.ImageCodecInfo codec = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders()[1]; System.Drawing.Imaging.EncoderParameters ep2 = new System.Drawing.Imaging.EncoderParameters(1); ep2.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L); g.DrawImage(bmp, new Rectangle(0,0,thumb.Width, thumb.Height)); try { thumb.Save(outFile, codec, ep2); return true; } catch { return false; } } }

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  • Securing a license key with RSA key.

    - by Jesse Knott
    Hello, it's late, I'm tired, and probably being quite dense.... I have written an application that I need to secure so it will only run on machines that I generate a key for. What I am doing for now is getting the BIOS serial number and generating a hash from that, I then am encrypting it using a XML RSA private key. I then sign the XML to ensure that it is not tampered with. I am trying to package the public key to decrypt and verify the signature with, but every time I try to execute the code as a different user than the one that generated the signature I get a failure on the signature. Most of my code is modified from sample code I have found since I am not as familiar with RSA encryption as I would like to be. Below is the code I was using and the code I thought I needed to use to get this working right... Any feedback would be greatly appreciated as I am quite lost at this point the original code I was working with was this, this code works fine as long as the user launching the program is the same one that signed the document originally... CspParameters cspParams = new CspParameters(); cspParams.KeyContainerName = "XML_DSIG_RSA_KEY"; cspParams.Flags = CspProviderFlags.UseMachineKeyStore; // Create a new RSA signing key and save it in the container. RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(cspParams) { PersistKeyInCsp = true, }; This code is what I believe I should be doing but it's failing to verify the signature no matter what I do, regardless if it's the same user or a different one... RSACryptoServiceProvider rsaKey = new RSACryptoServiceProvider(); //Load the private key from xml file XmlDocument xmlPrivateKey = new XmlDocument(); xmlPrivateKey.Load("KeyPriv.xml"); rsaKey.FromXmlString(xmlPrivateKey.InnerXml); I believe this to have something to do with the key container name (Being a real dumbass here please excuse me) I am quite certain that this is the line that is both causing it to work in the first case and preventing it from working in the second case.... cspParams.KeyContainerName = "XML_DSIG_RSA_KEY"; Is there a way for me to sign/encrypt the XML with a private key when the application license is generated and then drop the public key in the app directory and use that to verify/decrypt the code? I can drop the encryption part if I can get the signature part working right. I was using it as a backup to obfuscate the origin of the license code I am keying from. Does any of this make sense? Am I a total dunce? Thanks for any help anyone can give me in this..

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  • Corrupted version of WordPad [closed]

    - by Mike GH
    Somehow in trying to cleanup my computer's hard drive, I have inadvertently corrupted WordPad, which I have long used for viewing many types of files, including logs (i.e., log4j). Now when I right click one of these files and choose "open with" & WordPad, I get an error (fn is not a valid Win32 application). I've researched this issue, tried reinstalling wordpad.exe; bbut I still get the same error. Any suggestions would be appreciated.

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  • Why the concept of "Covariance" and "Contravariance" are applicable while implementing the methods o

    - by Amy
    The use case is some what like this: public class SomeClass: IClonable { // Some Code //Implementing interface method Public object Clone() { //Some Clonning Code } } Now my question is "Why is it not possible to use "SomeClass(As it is derivd from objec)" as a return type of Clone() method if we consider the Funda's of Covariance and Contravariance. Can somebody explain me the reason behind this implemementaion of Microsoft ????

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  • Castle ActiveRecord optimistic locking on properties

    - by Daniel T.
    Can Castle ActiveRecord do optimistic locking on properties? I found optimistic locking for the entire class, but not for an individual property. In my case, I need to make it so that adding/removing elements in a collection does not update the version number of the entity (so for example, adding a Product to a Store without changing any of Store's properties will not increment the version number).

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  • VB6 app not executing as scheduled task unless user is logged on

    - by Tedd Hansen
    Hi Would greatly apprechiate some help on this one! It may be a tricky one. :) Problem I have an VB6 application which is set up as scheduled task. It starts every time, but when executing CreateObject it fails if user is not logged on to computer. I am looking for information on what could cause this. Primary suspicion is that some Windows API fails. Key points Behaviour confirmed on Windows 2000, 2003, 2008 and Vista. The application executes as user X at scheduled time, executed by Windows Task Scheduler. It executes every time. Application does start! -- If user X is logged on via RDP it runs perfectly. (Note that user doesn't need to be connected, only logged on) -- If user X is not logged on to computer the application fails. Failure point Application fails when using CreateObject() to instansiate a DCOM object which is also part of the application. The DCOM objects declare .dll-references at startup (globally/on top of .bas-file) and run a small startup function. Failure must be during startup, possibly in one of the .dll-declarations. Thoughts After some Googling my initial suspicion was directed at MAPI. From what I could see MAPI required user to be logged on. The application has MAPI references. But even with all MAPI references removed it still does not work. What is the difference if an user is logged on? Registry mapping? Environment? explorer.exe is running. Isn't the user logged on when application executes as the user? What info would help? A definitive answer would be truly great. Any information regarding any VB6 feature/Windows API that could act differently depending on wether user is logged on or not would definitively help. Similar experiences may lead me in the right direction. Tips on debuggin this. Thanks! :)

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