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  • Examples of monoids/semigroups in programming

    - by jkff
    It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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  • How to detect if an application has UI elements in it from C# in Windows 7?

    - by Santhosh
    I have a c# application in Windows 7 that runs in Session 0. This application is basically a framework for software patches installation that will install patches in the background (in session 0). So this app will download patches from the server and start installing them on the client machines. The way it installs the patches is by calling CreateProcess("Patch.exe"). Now mostly, Patch.exe will be a non-ui silent installation and henceforth, installing the patch from session 0 goes through successfully. However, sometimes this Patch.exe happens to have some UI elements in it such as prompting the user for some details (like installation location, etc..) and let us say that these UI elements cannot be avoided. So is it possible for my installation framework (that runs in Session 0 written in C#), to know that the process Patch.exe which was created by my framework has any UI elements in it? The reason I ask is, if I determine that the application has any UI elements in it, then I do not want to continue with the installation (a crude way of doing this would be to kill the installer process Patch.exe, but that is a different story and not of concern here).

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  • Alternative to MS Project 2007 for production scheduling?

    - by john c
    OK... Im coming to grips with the fact that MS Project 2007 may not be the correct tool for my production scheduling. We serve 120 to 150 projects a year with durations from 6 weeks to 12 months. The task are simple (6 to 8 per project) and the resource pool is stable (15 to 20 people). It's really an assembly line product but with extremely varied durations. I need to be able to prioritize the projects for production and run projects concurrently to fully utilize my resources. What are the feelings of the stackoverflow community. Am I using the wrong program? I was really hoping to make this simple for non-programer types to input project data into a form and have the schedule software automated enough to make most of the decisions. Is there a better solution available commercially? I'd like to hold on writing a custom spreadsheet as a last resort but if that's the best route then so be it. Thank you so much for your input.

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  • What's the compelling reason to upgrade to Visual Studio 2010 from VS2008?

    - by Cheeso
    Are there new features in Visual Studio 2010 that are must-haves? If so, which ones? For me, the big draws for VS2008 as compared to VS2005 were LINQ, .NET Framework multitargeting, WCF (REST + Syndication), and general devenv.exe reliability. Granted, some of these features are framework things, and not tool things. For the purposes of this discussion, I'm willing to combine them into one bucket. What is the list of must-have features for VS2010 versus VS2008? Are there any? I am particularly interested in C#. Update: I know how to google, so I can get the official list from Microsoft. I guess what I really wanted was, the assessment from people using it, as to which things are really notable. Microsoft went on for 3 pages about 2008/3.5 features, and many people sort of boiled it down to LINQ, and a few other things. What is that short list for VS2010? Summary so far, what people think is cool or compelling: Visual Studio engine multi-monitor support new extensibility model based on WPF, prettier and more usable new TFS stuff, incl automated test tools parallel debugging .NET Framework parallel extensions for .NET C# 4.0 generic variance optional and named params easier interop with non-managed environments, like COM or Javascript VB 10.0 collection and array literals / initializers automatic properties anonymous methods / statement lambdas I read up on these at Zander's blog. He described these and other features. Nobody on this list said anything about: Visual Studio engine F# support Javascript code-completion JQuery is now included UML better Sharepoint capabilities C++ moves to msbuild project files

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  • KeyUp processed for wrong control

    - by Mikael
    I have made a simple test application for the issue, two winforms each containing a button. The button on the first form opens the other form when clicked. It also subscribes to keyup events. The second form has its button set as "AcceptButton" and in the Clicked event we sleep for 1s and then set DialogResult to true (the sleep is to simulate some processing done) When enter is used to close this second form the KeyUp event of the button on the first form is triggered, even though the key was released well before the second had passed so the second form was still shown and focused. If any key other then enter is pressed in the second form the event is not triggered for the button on the first form. First form: public Form1() { InitializeComponent(); buttonForm2.KeyUp += new KeyEventHandler(cntKeyUp); } void cntKeyUp(object sender, KeyEventArgs e) { MessageBox.Show(e.KeyCode.ToString()); } private void buttonForm2_Click(object sender, EventArgs e) { using (Form2 f = new Form2()) { f.ShowDialog(); } } Second form: private void button1_Click(object sender, EventArgs e) { Thread.Sleep(1000); this.DialogResult = DialogResult.OK; } Does anyone know why the event is triggered for the button on the non active form and what can be done to stop this from happening?

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  • Why boost property tree write_json saves everything as string? Is it possible to change that?

    - by pprzemek
    I'm trying to serialize using boost property tree write_json, it saves everything as strings, it's not that data are wrong, but I need to cast them explicitly every time and I want to use them somewhere else. (like in python or other C++ json (non boost) library) here is some sample code and what I get depending on locale: boost::property_tree::ptree root, arr, elem1, elem2; elem1.put<int>("key0", 0); elem1.put<bool>("key1", true); elem2.put<float>("key2", 2.2f); elem2.put<double>("key3", 3.3); arr.push_back( std::make_pair("", elem1) ); arr.push_back( std::make_pair("", elem2) ); root.put_child("path1.path2", arr); std::stringstream ss; write_json(ss, root); std::string my_string_to_send_somewhare_else = ss.str(); and my_string_to_send_somewhere_else is sth. like this: { "path1" : { "path2" : [ { "key0" : "0", "key1" : "true" }, { "key2" : "2.2", "key3" : "3.3" } ] } } Is there anyway to save them as the values, like: "key1" : true or "key2" : 2.2 ?

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  • Function returning dictionary, not seen by calling function

    - by twiga
    Hi There, I have an interesting problem, which is a function that returns a Dictionary<String,HashSet<String>>. The function converts some primitive structs to a Dictionary Class. The function is called as follows: Dictionary<String, HashSet<String>> Myset = new Dictionary<String,HashSet<String>>(); Myset = CacheConverter.MakeDictionary(_myList); Upon execution of the two lines above, Myset is non-existent to the debugger. Adding a watch results in: "The name 'Myset' does not exist in the current context" public Dictionary<String, HashSet<String>> MakeDictionary(LightWeightFetchListCollection _FetchList) { Dictionary<String, HashSet<String>> _temp = new Dictionary<String, HashSet<String>>(); // populate the Dictionary // return return _temp; } The Dictionary _temp is correctly populated by the called function and _temp contains all the expected values. The problem seems to be with the dictionary not being returned at all. Examples I could find on the web of functions returning primitive Dictionary<string,string> work as expected.

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  • java inserting special characters with preparedstatement fails

    - by phill
    I am using an HTML form which sends <input type=hidden name=longdesc value='SMARTNET%^" 8X5XNBD'> this is done by the following javascript code: function masinsert(id) { var currentTime=new Date(); var button = document.getElementById("m"+id); button.onclick=""; button.value="Inserting"; var itemdescription = document.getElementById("itemdescription"+id).value; function handleHttpResponse() { if (http.readyState == 4) { button.value="Item Added"; } } var http = getHTTPObject(); // We create the HTTP Object var tempUrl = "\AInsert"; tempUrl += "itemdescription="+itemdescription+"&"+"itemshortdescription="+itemdescription.substring(0,37)+; alert(tempUrl); http.open("GET", tempUrl, true); http.onreadystatechange = handleHttpResponse; http.send(null); } to a java servlet. AInsert.java in the AInsert.java file, I do a String itemdescription = request.getParameter("longdesc"); which then sends the value to a preparedstatement to run an insert query. In the query, there are sometimes special characters which throw it off. For example, when I run the following insert into itemdescription (longdesc) values ('SMARTNET%^" 8X5XNBD') here is the actual snippet: PreparedStatement ps = conn.prepareStatement("INSERT INTO itemdescription (longdesc) values(?)"); ps.setString(1, itemdescription); ps.executeUpdate(); It will produce an error saying : Cannot insert the value NULL into column 'LongDesc', table 'App.dbo.itemdescription'; column does not allow nulls. Insert fails I have tried urlencode/urldecode String encodedString = URLEncoder.encode(longdesc, "UTF-8"); String decitemdescription = URLDecoder.decode(itemdescription, "UTF-8"); and i've also tried these functions //BEGIN URL Encoder final static String[] hex = { "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07", "%08", "%09", "%0a", "%0b", "%0c", "%0d", "%0e", "%0f", "%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17", "%18", "%19", "%1a", "%1b", "%1c", "%1d", "%1e", "%1f", "%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27", "%28", "%29", "%2a", "%2b", "%2c", "%2d", "%2e", "%2f", "%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37", "%38", "%39", "%3a", "%3b", "%3c", "%3d", "%3e", "%3f", "%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47", "%48", "%49", "%4a", "%4b", "%4c", "%4d", "%4e", "%4f", "%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57", "%58", "%59", "%5a", "%5b", "%5c", "%5d", "%5e", "%5f", "%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67", "%68", "%69", "%6a", "%6b", "%6c", "%6d", "%6e", "%6f", "%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77", "%78", "%79", "%7a", "%7b", "%7c", "%7d", "%7e", "%7f", "%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87", "%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f", "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97", "%98", "%99", "%9a", "%9b", "%9c", "%9d", "%9e", "%9f", "%a0", "%a1", "%a2", "%a3", "%a4", "%a5", "%a6", "%a7", "%a8", "%a9", "%aa", "%ab", "%ac", "%ad", "%ae", "%af", "%b0", "%b1", "%b2", "%b3", "%b4", "%b5", "%b6", "%b7", "%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf", "%c0", "%c1", "%c2", "%c3", "%c4", "%c5", "%c6", "%c7", "%c8", "%c9", "%ca", "%cb", "%cc", "%cd", "%ce", "%cf", "%d0", "%d1", "%d2", "%d3", "%d4", "%d5", "%d6", "%d7", "%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df", "%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6", "%e7", "%e8", "%e9", "%ea", "%eb", "%ec", "%ed", "%ee", "%ef", "%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7", "%f8", "%f9", "%fa", "%fb", "%fc", "%fd", "%fe", "%ff" }; /** * Encode a string to the "x-www-form-urlencoded" form, enhanced * with the UTF-8-in-URL proposal. This is what happens: * * <ul> * <li><p>The ASCII characters 'a' through 'z', 'A' through 'Z', * and '0' through '9' remain the same. * * <li><p>The unreserved characters - _ . ! ~ * ' ( ) remain the same. * * <li><p>The space character ' ' is converted into a plus sign '+'. * * <li><p>All other ASCII characters are converted into the * 3-character string "%xy", where xy is * the two-digit hexadecimal representation of the character * code * * <li><p>All non-ASCII characters are encoded in two steps: first * to a sequence of 2 or 3 bytes, using the UTF-8 algorithm; * secondly each of these bytes is encoded as "%xx". * </ul> * * @param s The string to be encoded * @return The encoded string */ public static String encode(String s) { StringBuffer sbuf = new StringBuffer(); int len = s.length(); for (int i = 0; i < len; i++) { int ch = s.charAt(i); if ('A' <= ch && ch <= 'Z') { // 'A'..'Z' sbuf.append((char)ch); } else if ('a' <= ch && ch <= 'z') { // 'a'..'z' sbuf.append((char)ch); } else if ('0' <= ch && ch <= '9') { // '0'..'9' sbuf.append((char)ch); } else if (ch == ' ') { // space sbuf.append('+'); } else if (ch == '-' || ch == '_' // unreserved || ch == '.' || ch == '!' || ch == '~' || ch == '*' || ch == '\'' || ch == '(' || ch == ')') { sbuf.append((char)ch); } else if (ch <= 0x007f) { // other ASCII sbuf.append(hex[ch]); } else if (ch <= 0x07FF) { // non-ASCII <= 0x7FF sbuf.append(hex[0xc0 | (ch >> 6)]); sbuf.append(hex[0x80 | (ch & 0x3F)]); } else { // 0x7FF < ch <= 0xFFFF sbuf.append(hex[0xe0 | (ch >> 12)]); sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]); sbuf.append(hex[0x80 | (ch & 0x3F)]); } } return sbuf.toString(); } //end encode and //decode url private static String unescape(String s) { StringBuffer sbuf = new StringBuffer () ; int l = s.length() ; int ch = -1 ; int b, sumb = 0; for (int i = 0, more = -1 ; i < l ; i++) { /* Get next byte b from URL segment s */ switch (ch = s.charAt(i)) { case '%': ch = s.charAt (++i) ; int hb = (Character.isDigit ((char) ch) ? ch - '0' : 10+Character.toLowerCase((char) ch) - 'a') & 0xF ; ch = s.charAt (++i) ; int lb = (Character.isDigit ((char) ch) ? ch - '0' : 10+Character.toLowerCase ((char) ch)-'a') & 0xF ; b = (hb << 4) | lb ; break ; case '+': b = ' ' ; break ; default: b = ch ; } /* Decode byte b as UTF-8, sumb collects incomplete chars */ if ((b & 0xc0) == 0x80) { // 10xxxxxx (continuation byte) sumb = (sumb << 6) | (b & 0x3f) ; // Add 6 bits to sumb if (--more == 0) sbuf.append((char) sumb) ; // Add char to sbuf } else if ((b & 0x80) == 0x00) { // 0xxxxxxx (yields 7 bits) sbuf.append((char) b) ; // Store in sbuf } else if ((b & 0xe0) == 0xc0) { // 110xxxxx (yields 5 bits) sumb = b & 0x1f; more = 1; // Expect 1 more byte } else if ((b & 0xf0) == 0xe0) { // 1110xxxx (yields 4 bits) sumb = b & 0x0f; more = 2; // Expect 2 more bytes } else if ((b & 0xf8) == 0xf0) { // 11110xxx (yields 3 bits) sumb = b & 0x07; more = 3; // Expect 3 more bytes } else if ((b & 0xfc) == 0xf8) { // 111110xx (yields 2 bits) sumb = b & 0x03; more = 4; // Expect 4 more bytes } else /*if ((b & 0xfe) == 0xfc)*/ { // 1111110x (yields 1 bit) sumb = b & 0x01; more = 5; // Expect 5 more bytes } /* We don't test if the UTF-8 encoding is well-formed */ } return sbuf.toString() ; } but the decoding doesn't change it back to the original special characters. Any ideas? thanks in advance UPDATE: I tried adding these two statements to grab the request String itemdescription = URLDecoder.decode(request.getParameter("itemdescription"), "UTF-8"); String itemshortdescription = URLDecoder.decode(request.getParameter("itemshortdescription"), "UTF-8"); System.out.println("processRequest | short descrip "); and this is failing as well if that helps. UPDATE2: I created an html form and did a direct insert with the encoded itemdescription such as and the insertion works correctly with the special charaters and everything. I guess there is something going on with my javascript submit. Any ideas on this?

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  • My Thread Programs Block

    - by user315378
    I wrote a program that worked as a server. Knowing that "accept" was blocking the program. I wanted to launch a thread with this statement to prevent precisely that the program crashes, but this still happens. Can anybody help? Post code Thanks -(IBAction)Connetti{ if(switchConnessione.on){ int port = [fieldPort.text intValue]; labelStatus.text = [[NSString alloc] initWithFormat:@"Il Server è attivo"]; server_len = sizeof(server); server.sin_family = AF_INET; server.sin_port = htons((u_short)port); server.sin_addr.s_addr = INADDR_ANY; sd = socket (AF_INET, SOCK_STREAM, 0); bind(sd, (struct sockaddr*)&server, sizeof(server)); listen(sd, 1); [NSThread detachNewThreadSelector:@selector(startThreadAccept) toTarget:self withObject:nil]; } else { labelStatus.text = [[NSString alloc] initWithFormat:@"Server non attivo"]; switchChat.on = FALSE; switchChat.enabled = FALSE; } } -(void)startThreadAccept{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init]; [self performSelectorOnMainThread:@selector(acceptConnection) withObject:nil waitUntilDone:NO]; [pool release]; } -(void)acceptConnection{ new_sd = accept(sd, (struct sockaddr*)&server, &server_len); labelStatus.text = [[NSString alloc] initWithFormat:@"Ho accettato una connessione:%d", new_sd]; switchChat.enabled = TRUE; }

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  • WIKI replacement solution for SharePoint?

    - by Jakub
    I'm trying to research a replacement for the pathetic WIKI that comes with WSS (only wiki code it has is to create url links). I have looked at a few but most 'replacements' I see are MOSS only? (or so it just states MOSS for requirements). Has anyone faced this situation? What did you end up using? I would like something that I can have all in one location (not different apps, hence WSS). With LDAP / AD Integration like WSS. Thanks appreciate any input. I would like to see ~ $3k solutions tho (nothing super expensive, hence why we don't run MOSS). EDIT: Anyone else have any suggestions? EDIT2: Actually since I haven't had much feedback (thanks to those that have). I installed mediawiki under IIS with PHP enabled, and enabled the IIS AD hack for authentication. IIS ends up prompting for authentication (user/pass) if you use a non IE browser, then it sets the $_SERVER["REMOTE_USER"] variable, and grabs some AD info (groups etc). Works rather well, only issues is the UGLY urls so far. But its fully working. Seems like a good setup. Other than having to rely on MYSQL (my company strives to be mainly SQL Server)

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  • setlocale to fr-FR in PHP and number formatting

    - by bateman_ap
    Hi, I am trying to create a French version of one of my sites. I have set setlocale(LC_ALL, 'fr_FR'); at the top of my page, and using strftime I am displaying dates correctly in the French style. However I am having some problems with a number. Part of the page uses data I am getting from a Web Service. I am assigning a returned value to a var like this: $overallRating = $returnArray['Overall']; I am then using the following code later to format it to 1 decimal place number_format($overallRating,1) In the English version the overallRating value might be 7.5 and returns a value such as 7.5 (the reason for running it through the number_format is if it returns 7 I want it to display 7.0) However in the French version if I print out the raw $overallRating value I get 7,5 which looks like it has translated it into french. This would be fine but if I run it through number_format I get the error: Notice: A non well formed numeric value encountered in /sites/index.php on line 250 Line 250 is the number_format line I presume the translation to 7,5 is messing it up, but not sure how to solve this... Using PHP 5.3 in case there is anything new that helps me

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  • typed-dataset initializer problem with C# windows app.

    - by Eyla
    Greetings, I'm working in windows application using C#. I have typed-dataset called packetsDBDataSet and it has table adapter called packetsTableAdapter with method to insert data called InsertPackets(). when I want to insert new data I used a code that I used before with asp.net page and it was working ok but not I'm getting error. here is the code: public packetsDBDataSetTableAdapters.packetsTableAdapter ds = new packetsDBDataSetTableAdapters.packetsTableAdapter(); public packetsDBDataSet.packetsDataTable insert = ds.InsertPackets(); and here is the error: Error 1 A field initializer cannot reference the non-static field, method, or property 'Packets.Form1.ds' C:\Users\Ali\Documents\Visual Studio 2008\Projects\Packets-3\Packets\Packets\Form1.cs 26 59 Packets I already included to my project: using Packets; using Packets.packetsDBDataSetTableAdapters; please advice to solve this problem. Update : I also tried : public packetsDBDataSetTableAdapters.packetsTableAdapter ds = new packetsDBDataSetTableAdapters.packetsTableAdapter(); ds.InsertPackets("1","2","3"); and I'm getting this error: Error 1 Invalid token '(' in class, struct, or interface member declaration C:\Users\Ali\Documents\Visual Studio 2008\Projects\Packets-3\Packets\Packets\Form1.cs 28 29 Packets

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  • Is this a clean way to manage AsyncResults with Generic Methods?

    - by Michael Stum
    I've contributed Async Support to a Project I'm using, but I made a bug which I'm trying to fix. Basically I have this construct: private readonly Dictionary<WaitHandle, object> genericCallbacks = new Dictionary<WaitHandle, object>(); public IAsyncResult BeginExecute<T>(RestRequest request, AsyncCallback callback, object state) where T : new() { var genericCallback = new RequestExecuteCaller<T>(this.Execute<T>); var asyncResult = genericCallback.BeginInvoke(request, callback, state); genericCallbacks[asyncResult.AsyncWaitHandle] = genericCallback; return asyncResult; } public RestResponse<T> EndExecute<T>(IAsyncResult asyncResult) where T : new() { var cb = genericCallbacks[asyncResult.AsyncWaitHandle] as RequestExecuteCaller<T>; genericCallbacks.Remove(asyncResult.AsyncWaitHandle); return cb.EndInvoke(asyncResult); } So I have a generic BeginExecute/EndExecute method pair. As I need to store the delegate that is called on EndExecute somewhere I created a dictionary. I'm unsure about using WaitHandles as keys though, but that seems to be the only safe choice. Does this approach make sense? Are WaitHandles unique or could I have two equal ones? Or should I instead use the State (and wrap any user provided state into my own State value)? Just to add, the class itself is non-generic, only the Begin/EndExecute methods are generic.

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  • Search book by title, and author

    - by Swoosh
    I got a table with columns: author firstname, author lastname, and booktitle Multiple users are inserting in the database, through an import, and I'd like to avoid duplicates. So I'm trying to do something like this: I have a record in the db: First Name: "Isaac" Last Name: "Assimov" Title: "I, Robot" If the user tries to add it again, it would be basically a non-split-text (would not be split up into author firstname, author lastname, and booktitle) So it would basically look like this: "Isaac Asimov - I Robot" or "Asimov, Isaac - I Robot" or "I Robot by Isaac Asimov" You see where I am getting at? (I cannot force the user to split up all the books into into author firstname, author lastname, and booktitle, and I don't even like the idea to force the user, because it's not too user-friendly) What is the best way (in SQL) to compare all this possible bookdata scenarios to what I have in the database, not to add the same book twice. I was thinking about a possibility of suggesting the user: "is THIS the book you are trying to add?" (imagine a list instead of the THIS word, just like on stackoverflow - ask question - Related Questions. I was thinking about soundex and maybe even the like operators, but so far i didn't get the results i was hoping.

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  • Memory allocation in detached NSThread to load an NSDictionary in background?

    - by mobibob
    I am trying to launch a background thread to retrieve XML data from a web service. I developed it synchronously - without threads, so I know that part works. Now I am ready to have a non-blocking service by spawning a thread to wait for the response and parse. I created an NSAutoreleasePool inside the thread and release it at the end of the parsing. The code to spawn and the thread are as follows: Spawn from main-loop code: . . [NSThread detachNewThreadSelector:@selector(spawnRequestThread:) toTarget:self withObject:url]; . . Thread (inside 'self'): -(void) spawnRequestThread: (NSURL*) url { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; parser = [[NSXMLParser alloc] initWithContentsOfURL:url]; [self parseContentsOfResponse]; [parser release]; [pool release]; } The method parseContentsOfResponse fills an NSMutableDictionary with the parsed document contents. I would like to avoid moving the data around a lot and allocate it back in the main-loop that spawned the thread rather than making a copy. First, is that possible, and if not, can I simply pass in an allocated pointer from the main thread and allocate with 'dictionaryWithDictionary' method? That just seems so inefficient. Are there perferred designs?

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  • ASP.Net HttpModule List<> content

    - by test
    We have created an http module that loads data on initialize into a list, and uses that list on every endrequest event of application. However we got a null reference exception on the module at endRequest event complaining that the content is null. Yet we are sure that at module initialization we have put non-null objects correctly. How is this possible? Any ideas? Thanks in advance. The place where i fill the data into the list what named as "Pages" : using (SqlDataReader reader = cmd.ExecuteReader()) { while (reader.Read()) { LandingPageDetails details = new LandingPageDetails(); details.DomainId = Convert.ToInt32(reader["DomainId"]); details.PageId = Convert.ToInt32(reader["TrackingPageId"]); details.PageAddress = Convert.ToString(reader["PageAddress"]); if (!string.IsNullOrEmpty(details.PageAddress)) { Pages.Add(details); } } } // Find the related record on EndRequesst event LandingPageDetails result = Pages.Find ( delegate(LandingPageDetails current) { return current.PageAddress.Equals(url, StringComparison.InvariantCultureIgnoreCase); } ); The line what we get the error return current.PageAddress.Equals(url, StringComparison.InvariantCultureIgnoreCase); "current" is the null object P.S : It works properly, but one day later contents become null. Possibly, there is something wrong on IIS. Our server is Windows 2003, IIS 6.0

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  • Dynamically populated NSPopUpButtonCell menu in an NSOutlineView

    - by Mo
    I’m working with an NSOutlineView which has two columns. My dataSource supplies the outline view with a tree of items of a custom class which represents file types (that is, you initialise it with a UTI). The first column is the display name of the file type (e.g., “Source code”, “Interface Builder NIB document”, etc.). The second column is an NSPopUpButtonCell which is supposed to allow the user to pick a handler for the given document type (think of Xcode’s “File Types” preference pane, and you’re pretty much there). I can generate an NSMenu for a given item in the tree, populated with options based upon the Launch Services database entries for the UTI, complete with the relevant application icon and and so on. In fact, the menu itself works wonderfully, populated by way of NSPopUpButtonCellWillPopUpNotification. The problem is, try as I might, the cell when the menu isn’t popped up always contains precisely one of two things: either an empty string, or the default text for the cell, the former if the result of -handlerName on the item (the attribute assigned to the column) is non-nil, the latter otherwise. Moreover, I’m manually calling -selectItem: on the NSPopUpButtonCell instance, which just seems Wrong. In contrast, the left-hand column, which is just an NSTextFieldCell, everything just works (although granted, all it’s got to do is read the value from the item and present it). (Disclaimer: I’m fairly new at Cocoa UI stuff; I know Objective-C, and lots of other programming languages, but I’ve not a huge amount of experience of building Mac OS X UIs, so be gentle).

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  • MongoDB - proper use of collections?

    - by zmg
    In Mongo my understanding is that you can have databases and collections. I'm working on a social-type app that will have blogs and comments (among other things) and had previously be using MySQL and pretty heavy partitioning in an attempt to limit possible concurrency issues. With MySQL I've stuffed all my user data into a _user database with several tables to further partition the data (blogs, pages, etc). My immediate reaction with Mongo would be to create a 'users' database with one collection per user. In this way user 'zach' blog entries would go into the 'zach' collection with associated comments and such becoming sub-objects in the same collection. Basically like dynamically creating one table per user in MySQL, but apparently without the complexity and limitations that might impose. Of course since I haven't really used Mongo before I'm having trouble gauging the (ahem..) quality of this idea and the potential problems it might cause down the road. I'd like user data to be treated a lot like a users directory in a *nix environment where user created/non-shared (mostly) gets put into one place (currently with MySQL that would be the appname_users as mentioned above). Most of the users data will be specific to the users page(s). Some of the user data which is queried across all site users (searchable user profiles) is currently kept in a separate database/table and I expect things like this could be put into a appname_system database and be broken up into collections and/or application specific databases (appname_profiles). Anyway, since the available documentation on this is currently a little thin and my experience is extremely limited I thought I might find a little guidance from someone with a better working understanding of the system. On the plus side I'd really already been attempting to treat MySQL as a schema-less document-store and doing this with Mongo seems much more intuitive/sane/rational so I'm really looking forward to getting started. Thanks, Zach

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  • twisted deferred/callbacks and asynchronous execution

    - by NetSkay
    hey guys, quick question about twisted and python... im trying to figure out how can i make my code more asynchronous using twisted and ive come to sort of a dead end, if a function of mine returns a deferred object, then i add a list of callbacks, the first callback will be called after the deferred function provides some result through deferred_obj.callback, then, in the chain of callbacks, the first callback will do something with the data and call the second callback and etc. however chained callbacks will not be considered asynchronous because they're chained and the event loop will keep firing each one of them concurrently until there is no more, right? however, if i have a deferred object, and i attach as its callback the deferred_obj.callback as in d.addCallback(deferred_obj.callback) then this will be considered asynchronous, because the deferred_obj is waiting for the data, and then the method that will pass the data is waiting on data as well, however once i d.callback 'd' object processes the data then it call deferred_obj.callback however since this object is deferred, unlike the case of chained callbacks, it will execute asynchronously... correct? meaning chained callbacks are NOT asynchronous while chained deferreds are, correct? thank you PS: assuming all of my code is non-blocking

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  • Http Digest Authentication, Handle different browser char-sets...

    - by user160561
    Hi all, I tried to use the Http Authentication Digest Scheme with my php (apache module) based website. In general it works fine, but when it comes to verification of the username / hash against my user database i run into a problem. Of course i do not want to store the user´s password in my database, so i tend to store the A1 hashvalue (which is md5($username . ':' . $realm . ':' . $password)) in my db. This is just how the browser does it too to create the hashes to send back. The Problem: I am not able to detect if the browser does this in ISO-8859-1 fallback (like firefox, IE) or UTF-8 (Opera) or whatever. I have chosen to do the calculation in UTF-8 and store this md5 hash. Which leads to non-authentication in Firefox and IE browsers. How do you solve this problem? Just do not use this auth-scheme? Or Store a md5 Hash for each charset? Force users to Opera? (Terms of A1 refer to the http://php.net/manual/en/features.http-auth.php example.) (for digest access authentication read the according wikipedia entry)

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  • Simple description of worker and I/O threads in .NET

    - by Konstantin
    It's very hard to find detailed but simple description of worker and I/O threads in .NET What's clear to me regarding this topic (but may not be technically precise): Worker threads are threads that should employ CPU for their work; I/O threads (also called "completion port threads") should employ device drivers for their work and essentially "do nothing", only monitor the completion of non-CPU operations. What is not clear: Although method ThreadPool.GetAvailableThreads returns number of available threads of both types, it seems there is no public API to schedule work for I/O thread. You can only manually create worker thread in .NET? It seems that single I/O thread can monitor multiple I/O operations. Is it true? If so, why ThreadPool has so many available I/O threads by default? In some texts I read that callback, triggered after I/O operation completion is performed by I/O thread. Is it true? Isn’t this a job for worker thread, considering that this callback is CPU operation? To be more specific – do ASP.NET asynchronous pages user I/O threads? What exactly is performance benefit in switching I/O work to separate thread instead of increasing maximum number of worker threads? Is it because single I/O thread does monitor multiple operations? Or Windows does more efficient context switching when using I/O threads?

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  • DataGrid - Edit the selected row when a button is clicked.

    - by Chepech
    Hi all. I have a very simple DataGrid with 2 columns, some thing like this: <mx:DataGrid id="grid" > <mx:columns> <mx:DataGridColumn dataField="name" headerText="Name"/> <mx:DataGridColumn dataField="date" headerText="Date"/> </mx:columns> </mx:DataGrid> What Im trying to do is to activate the edition of the selected row when the user clicks a button. So far I've been unable to find any example of how to do this. I already tried 6 or 7 different approaches but non works. Does any one has a clue how to do this? How do you get the selected row (NOT selectedItem) of a DataGrid and how can you: Change the ItemRenderEditor or ItemRenderer on the fly of just that row. Or enable the edition of that specific row without clicking it. This are the questions that I've been unable to answer Help will be greatly appreciated.

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  • How to use DLL reference with an ActiveX <object> via JavaScript

    - by John Factorial
    My question: how can I set an ActiveX object's property via JavaScript to an enum value found in a non-ActiveX DLL? Problem description: I am instantiating an ActiveX object with the following object tag: <object classid="clsid:F338193D-2491-4D7B-80CE-03487041A278" id="VideoCapture1" width="500" height="500"></object> (This is the guid for the 3rd party ActiveX I'm using, "VisioForge_Video_Capture_4.VFVideoCapture4X") I have example C# code for using this ActiveX, which I am porting to JavaScript. Code like this works just fine: VideoCapture1.Debug_Mode = true; var devcount = VideoCapture1.Video_CaptureDevices_GetCount(); var devs = []; for (var i =0; i < devcount; ++i) { devs[devs.length] = VideoCapture1.Video_CaptureDevices_GetItem(i); } ... etc ... However, VideoCapture1 has some settings which refer to a DLL enum, like so (C# code): VideoCapture1.Mode = VisioForge_Video_Capture_4.TxVFMode.Mode_Video_Preview; I can see in Visual Web Developer that TxVFMode.Mode_Video_Preview is value 1 in the enum. However, the following JS does not appear to set the Mode properly: VideoCapture1.Mode = 1; Does anyone know how I can set VideoCapture1.Mode to the enum value found in the TxVFMode? PS: In Visual Web Developer, when I "Go to definition" on TxVFMode, I get the Guid for the enum. I thought I could create an with this Guid or instantiate a VisioForge_Video_Capture_4.TxVFMode in JS, but neither gives me a usable object.

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  • How large a role does subjectiveness play in programming?

    - by Bob
    I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP. Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing. What role does subjectiveness play within the programming realm? Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting. The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance. But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought. It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work. Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?

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  • Is there a good way to QuickCheck Happstack.State methods?

    - by Paul Kuliniewicz
    I have a set of Happstack.State MACID methods that I want to test using QuickCheck, but I'm having trouble figuring out the most elegant way to accomplish that. The problems I'm running into are: The only way to evaluate an Ev monad computation is in the IO monad via query or update. There's no way to create a purely in-memory MACID store; this is by design. Therefore, running things in the IO monad means there are temporary files to clean up after each test. There's no way to initialize a new MACID store except with the initialValue for the state; it can't be generated via Arbitrary unless I expose an access method that replaces the state wholesale. Working around all of the above means writing methods that only use features of MonadReader or MonadState (and running the test inside Reader or State instead of Ev. This means forgoing the use of getRandom or getEventClockTime and the like inside the method definitions. The only options I can see are: Run the methods in a throw-away on-disk MACID store, cleaning up after each test and settling for starting from initialValue each time. Write the methods to have most of the code run in a MonadReader or MonadState (which is more easily testable), and rely on a small amount of non-QuickCheck-able glue around it that calls getRandom or getEventClockTime as necessary. Is there a better solution that I'm overlooking?

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