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  • Which are the RDBMS that minimize the server roundtrips? Which RDBMS are better (in this area) than

    - by user193655
    When the latency is high ("when pinging the server takes time") the server roundtrips make the difference. Now I don't want to focus on the roundtrips created in programming, but the roundtrips that occur "under the hood" in the DB engine, so the roundtrips that are 100% dependant on how the RDBMS is written itself. I have been told that FireBird has more roundtrips than MySQL. But this is the only information I know. I am currently supporting MS SQL but I'd like to change RDBMS (because I use Express Editions and in my scenario they are quite limiting from the performance point of view), so to make a wise choice I would like to include also this point into "my RDBMS comparison feature matrix" to understand which is the best RDBMS to choose as an alternative to MS SQL. So the bold sentence above would make me prefer MySQL to Firebird (for the roundtrips concept, not in general), but can anyone add informations? And MS SQL where is it located? Is someone able to "rank" the roundtrip performance of the main RDBMS, or at least: MS SQL, MySql, Postegresql, Firebird (I am not interested in Oracle since it is not free, and if I have to change I would change to a free RDBMS). Anyway MySql (as mentioned several times on stackoverflow) has a not clear future and a not 100% free license. So my final choice will probably dall on PostgreSQL or Firebird. Additional info: somehow you can answer my question by making a simple list like: MSSQL:3; MySQL:1; Firebird:2; Postgresql:2 (where 1 is good, 2 average, 3 bad). Of course if you can post some links where the roundtrips per RDBMSs are compared it would be great

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  • To what extent should code try to explain fatal exceptions?

    - by Andrzej Doyle
    I suspect that all non-trivial software is likely to experience situations where it hits an external problem it cannot work around and thus needs to fail. This might be due to bad configuration, an external server being down, disk full, etc. In these situations, especially if the software is running in non-interactive mode, I expect that all one can really do is log an error and wait for the admin to read the logs and fix the problem. If someone happens to interact with the software in the meantime, e.g. a request comes in to a server that failed to initialize properly, then perhaps an appropriate hint can be given to check the logs and maybe even the error can be echoed (depending on whether you can tell if they're a technical guy as opposed to a business user). For the moment though let's not think too hard about this part. My question is, to what extent should the software be responsible for trying to explain the meaning of the fatal error? In general, how much competence/knowledge are you allowed to presume on administrators of the software, and how much should you include troubleshooting information and potential resolution steps when logging fatal errors? Of course if there's something that's unique to the runtime context this should definitely be logged; but lets assume your software needs to talk to Active Directory via LDAP and gets back an error "[LDAP: error code 49 - 80090308: LdapErr: DSID-0C090334, comment: AcceptSecurityContext error, data 525, vece]". Is it reasonable to assume that the maintainers will be able to Google the error code and work out what it means, or should the software try to parse the error code and log that this is caused by an incorrect user DN in the LDAP config? I don't know if there is a definitive best-practices answer for this, so I'm keen to hear a variety of views.

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  • Which book should I pick to improve my program designs/design patterns?

    - by zxcvbnm
    I want to learn about design patterns and from what I've seen the most recommended ones are the Gang of Four's Design Patterns and Head First Design Patterns. There are also language specific books, but I never see them recommended. I suppose it ties you to whatever strengths/weaknesses are inherent to each language, so not a good idea to learn design patterns in general. The Gang of Four's book is kinda old, so I'm wondering if there isn't a better alternative out today? I've heard the Heard First one isn't quite as good. But I'm not sure why, so it's really hard to pick either one. I've see some answers on this very site recommending both, but if I can only read one, which should I pick? I've been coding for 3+ years, though I've never had a good class on this subject. Also, would a book like Code Complete help me with this? One more thing: how often are these techniques supposed to be useful? For example, this question has me wondering if this stuff is worth the trouble. And please, tell me more than just "read x". I'd like to know why you're suggesting x.

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  • Unable to create a breakpoint in Eclipse and Tomcat

    - by Traroth
    Since yesterday, I get a strange error message when I start my Tomcat (6.0.35) under Eclipse Juno (build 20120614-1722): Among the things I tried in order to get rid of the error: Check in Preferences - Java - Compiler if all "Classfile Generation" checkboxes where checked. I did that for both general preferences and project preference Uncheck them, build, check them build again (found on another question) Add org.eclipse.jdt.core.compiler.debug.lineNumber=generate to my .settings/org.eclipse.jdt.core.prefs file Use a new CVS checkout (same symptoms) And now, I don't know what to do anymore. The problem is really stopping me from get anything done. I can't work anymore. Crazy is: the problem doesn't happen on every class, only on some of them. Neither does it happen on my other Eclipse projects. And it didn't happen before yesterday, even if I can't remeber having done anything weird. Actually, I have never seen a problem like this in almost 10 years I'm using Eclipse... If you have any idea, I would be really grateful... Edit: I also tried to ignore the message and go on with my tests: If I create another breakpoint upstream from my problematic class, when I enter this problematic class, it tries to open a $Proxy132 class, which means it actually opens an empty page, with a source not found message

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  • Why can't I roll a loop in Javascript?

    - by Carl Manaster
    I am working on a web page that uses dojo and has a number (6 in my test case, but variable in general) of project widgets on it. I'm invoking dojo.addOnLoad(init), and in my init() function I have these lines: dojo.connect(dijit.byId("project" + 0).InputNode, "onChange", function() {makeMatch(0);}); dojo.connect(dijit.byId("project" + 1).InputNode, "onChange", function() {makeMatch(1);}); dojo.connect(dijit.byId("project" + 2).InputNode, "onChange", function() {makeMatch(2);}); dojo.connect(dijit.byId("project" + 3).InputNode, "onChange", function() {makeMatch(3);}); dojo.connect(dijit.byId("project" + 4).InputNode, "onChange", function() {makeMatch(4);}); dojo.connect(dijit.byId("project" + 5).InputNode, "onChange", function() {makeMatch(5);}); and change events for my project widgets properly invoke the makeMatch function. But if I replace them with a loop: for (var i = 0; i < 6; i++) dojo.connect(dijit.byId("project" + i).InputNode, "onChange", function() {makeMatch(i);}); same makeMatch() function, same init() invocation, same everything else - just rolling my calls up into a loop - the makeMatch function is never called; the objects are not wired. What's going on, and how do I fix it? I've tried using dojo.query, but its behavior is the same as the for loop case.

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  • Looking to reimplement build toolchain from bash/grep/sed/awk/(auto)make/configure to something more

    - by wash
    I currently maintain a few boxes that house a loosely related cornucopia of coding projects, databases and repositories (ranging from a homebrew *nix distro to my class notes), maintained by myself and a few equally pasty-skinned nerdy friends (all of said cornucopia is stored in SVN). The vast majority of our code is in C/C++/assembly (a few utilities are in python/perl/php, we're not big java fans), compiled in gcc. Our build toolchain typically consists of a hodgepodge of make, bash, grep, sed and awk. Recent discovery of a Makefile nearly as long as the program it builds (as well as everyone's general anxiety with my cryptic sed and awking) has motivated me to seek a less painful build system. Currently, the strongest candidate I've come across is Boost Build/Bjam as a replacement for GNU make and python as a replacement for our build-related bash scripts. Are there any other C/C++/asm build systems out there worth looking into? I've browsed through a number of make alternatives, but I haven't found any that are developed by names I know aside from Boost's. (I should note that an ability to easily extract information from svn commandline tools such as svnversion is important, as well as enough flexibility to configure for builds of asm projects as easily as c/c++ projects)

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  • Problem with OnSubmit in Validation plugin in jQuery

    - by novellino
    Hello, I an quite new to jQuery and I have a problem while trying to create a form. I am using the Validation plugin for validate the email (one the form's field). When I click the Submit button I want to call my own function because I want to save the data in an XML file. This is my button: (as I understood the plugin uses "submit" for understand the button) <input type="submit" name="submit" class="submit" id="submit_btn" value="Send"/> and here is the script for the validation: <script type="text/javascript"> $(document).ready(function() { //this is my form $("#contactForm").validate(); /*save the valid data in the xml*/ $(".submit").click(function() { var email = $("input#email").val(); var subject = $("input#subject").val(); var message = $("textarea#message").val(); if (email == "" || !$("#contactForm").valid()) { return false; } var dataString = 'email='+ email + '&subject=' + subject + '&message=' + message; //alert("DATA: " +dataString); $.ajax({ type: "POST", url: "SaveData.jsp", data: dataString, success: function(data){} }); return false; }); }); </script> In general it works ok but I have two basic problems. When I click the button in the beginning having all the form empty, I get no message for the field required. Also when the data are valid and I am doing the submit, the form does not become clear after the submit. If I deleted this script code, these actions are working properly but I can not save the data! Does anyone know what is wrong? Thanks a lot!

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  • Website: Make printable version with footnotes?

    - by DavidR
    I have a website that uses editable divs so that a user can modify or make notes to a text. Is there a way I can have the website generate a pdf or some printable document with footnotes, such that if a user has this: <div class="text" id="text_1"> <div class="bodyTest">This is the body text</div> <div class="notes">These are the notes</div> </div> <div class="text" id="text_2"> <div class="bodyTest">This is the body text</div> <div class="notes">These are the notes</div> </div> the website will generate a printable version (or document) in such a way thatdiv.notes will appear as a footnote on the same page on which div#text_1 appears? I don't need a full answer, just a shove in the general direction will be amazing. Thanks.

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  • Core Data: migrating entities with self-referential properties

    - by Dan
    My Core Data model contains an entity, Shape, that has two self-referential relationships, which means four properties. One pair is a one-to-many relationship (Shape.containedBy <- Shape.contains) and the another is a many-to-many relationship (Shape.nextShapes <<- Shape.previousShapes). It all works perfectly in the application, so I don't think self-referencing relationships is a problem in general. However, when it comes to migrating the model to a new version, then Xcode fails to compile the automatically generated mapping model, with this error message: 2009-10-30 17:10:09.387 mapc[18619:607] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse the format string "FUNCTION($manager ,'destinationInstancesForSourceRelationshipNamed:sourceInstances:' , 'contains' , $source.contains) == 1"' *** Call stack at first throw: ( 0 CoreFoundation 0x00007fff80d735a4 __exceptionPreprocess + 180 1 libobjc.A.dylib 0x00007fff83f0a313 objc_exception_throw + 45 2 Foundation 0x00007fff819bc8d4 _qfqp2_performParsing + 8412 3 Foundation 0x00007fff819ba79d +[NSPredicate predicateWithFormat:arguments:] + 59 4 Foundation 0x00007fff81a482ef +[NSExpression expressionWithFormat:arguments:] + 68 5 Foundation 0x00007fff81a48843 +[NSExpression expressionWithFormat:] + 155 6 XDBase 0x0000000100038e94 -[XDDevRelationshipMapping valueExpressionAsString] + 260 7 XDBase 0x000000010003ae5c -[XDMappingCompilerSupport generateCompileResultForMappingModel:] + 2828 8 XDBase 0x000000010003b135 -[XDMappingCompilerSupport compileSourcePath:options:] + 309 9 mapc 0x0000000100001a1c 0x0 + 4294973980 10 mapc 0x0000000100001794 0x0 + 4294973332 ) terminate called after throwing an instance of 'NSException' Command /Developer/usr/bin/mapc failed with exit code 6 The 'contains' is the name of one of the self-referential properties. Anyway, the really big problem is that I can't even look at this Mapping Property as Xcode crashes as soon as I select the entity mapping when viewing the mapping model. So I'm a bit lost really where to go from here. I really can't remove the self-referential properties, so I'm thinking I've got manually create a mapping model that compiles? Any ideas? Cheers

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  • How does PATH environment affect my running executable from using msvcr90 to msvcr80 ???

    - by Runner
    #include <gtk/gtk.h> int main( int argc, char *argv[] ) { GtkWidget *window; gtk_init (&argc, &argv); window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_widget_show (window); gtk_main (); return 0; } I tried putting various versions of MSVCR80.dll under the same directory as the generated executable(via cmake),but none matched. Is there a general solution for this kinda problem? UPDATE Some answers recommend install the VS redist,but I'm not sure whether or not it will affect my installed Visual Studio 9, can someone confirm? Manifest file of the executable <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0"> <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3"> <security> <requestedPrivileges> <requestedExecutionLevel level="asInvoker" uiAccess="false"></requestedExecutionLevel> </requestedPrivileges> </security> </trustInfo> <dependency> <dependentAssembly> <assemblyIdentity type="win32" name="Microsoft.VC90.DebugCRT" version="9.0.21022.8" processorArchitecture="x86" publicKeyToken="1fc8b3b9a1e18e3b"></assemblyIdentity> </dependentAssembly> </dependency> </assembly> It seems the manifest file says it should use the MSVCR90, why it always reporting missing MSVCR80.dll? FOUND After spending several hours on it,finally I found it's caused by this setting in PATH: D:\MATLAB\R2007b\bin\win32 After removing it all works fine.But why can that setting affect my running executable from using msvcr90 to msvcr80 ???

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  • Sql Server Compact Edition version error.

    - by Tim
    I am working on .NET ClickOnce project that uses Sql Server 2005 Compact Edition to synchronize remote data through the use of a Merge replication. This application has been live for nearly a year now, and while we encounter occasional synchronization errors, things run quite smoothly for the most part. Yesterday a user reported an error that I have never seen before and have yet to find any information for online. Many users synchronize every night, and I haven't received error reports from anyone else, so this issue must be isolated to this particular user / client machine. Here are the full details of the error: -Error Code : 80004005 -Message : The message contains an unexpected replication operation code. The version of SQL Server Compact Edition Client Agent and SQL Server Compact Edition Server Agent should match. [ replication operation code = 31 ] -Minor Error : 28526 -Source : Microsoft SQL Server Compact Edition -Numeric Parameters : 31 One interesting thing that I've found is that his data does get synchronized to the server, so this error must occur after the upload completes. I have yet to determine whether or not changes at the server are still being downloaded to his subscription. Thinking that maybe there was some kind of version conflict going on, I had a remote desktop session with this user last night and uninstalled both the application and the SQL Server Compact Edition prerequisite, then reinstalled both from our ClickOnce publication site. I also removed his existing local database file so that upon synchronization, an entirely new subscription would be issued to him. Still his errors continue. I suppose the error may be somewhat general, and the text in the error message stating that the versions should match may not necessarily reflect the problem at hand. This site contains the only official reference to this error that I've been able to find, and it offers no more detail than the error message itself. Has anyone else encountered this error? Or at least know more about SQL Compact to have a better guess as to what is going on here? Any help / suggestions will be greatly appreciated!

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  • sqlite3 'database is locked' won't go away with retries

    - by Azarias
    I have a sqlite3 database that is accessed by a few threads (3-4). I am aware of the general limitations of sqlite3 with regards to concurrency as stated http://www.sqlite.org/faq.html#q6 , but I am convinced that is not the problem. All of the threads both read and write from this database. Whenever I do a write, I have the following construct: try: Cursor.execute(q, params) Connection.commit() except sqlite3.IntegrityError: Notify except sqlite3.OperationalError: print sys.exc_info() print("DATABASE LOCKED; sleeping for 3 seconds and trying again") time.sleep(3) Retry On some runs, I won't even hit this block, but when I do, it never comes out of it (keeps retrying, but I keep getting the 'database is locked' error from exc_info. If I understand the reader/writer lock usage correctly, some amount of waiting should help with the contention. What this sounds like is deadlock, but I do not use any transactions in my code, and every SELECT or INSERT is simply a one off. Some threads, however, keep the same connection when they do their operation (which includes a mix of SELECTS and INSERTS and other modifiers). I would appericiate it if you could shade a light on this, and also ways around fixing it (besides using a different database engine.)

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  • I would like to interactively detect when an ActiveX component has been installed, and asynchronousl

    - by Brian Stinar
    Hello, I am working on a website, and I would like to refresh a portion of the page after an ActiveX component has been installed. I have a general idea of how to do this with polling, which I am working on getting going : function detectComponentThenSleep(){ try{ // Call what I want ActiveX for, if the method is available, or // ActiveXComponent.object == null --- test for existance document.getElementById("ActiveXComponent").someMethod(); } catch{ // Try again, if the method is not available setTimeout(detectComponentThenSleep, 100); } } However, what I would REALLY like to do is something like this: ActiveXObject.addListener("onInstall", myfunction); I don't actually have the source for the ActiveX component, but I have complete control of the page I am hosting it on. I would like to use JavaScript, if possible, to accomplish this. So, my question is 1.) will this actually work with the polling method? and 2.) Is there an interrupt/listener like way of doing this? I am sure I am missing something with connecting the dots here, I can already detect if the component is present, but I am having trouble doing this asynchronously. Thank you very much for your time and help, -Brian J. Stinar-

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  • ParseKit.framework won't work, Foundation.h not found

    - by Jeremy
    I'm really stumped trying to get the ParseKit.framework (this) to work in general, not even bothering to implement it till it runs the demo app that comes with it. What happens is the compiler can't locate < Foundation/Foundation.h or something, which I thought the header was in the linked framework. Exact error: "Lexical or Preprocessor Issue: 'Foundation/Foundation.h' file not found." Here's the code, just from the ParseKit_Prefix.pch: // // Prefix header for all source files of the 'ParseKit' target in the 'ParseKit' project. //#ifdef __OBJC__ #import <Foundation/Foundation.h> #endif Nothing unusual about it, did I mess up the file paths some how? I've reinstalled Xcode, re-downloaded the ParseKit, and nothing is helping. The suggestions here did nothing and it's not this. When I make a new project or use a different project and load the Foundation.framework and #import the header it works just fine. If I unlink the framework I can't find it to re-link again. Has anyone else had this kind of problem? Did I download it wrong somewhere? I have a very difficult time finding where exactly the Xcode UI links stuff, apple must get a kick out of frustrating people, so if anyone has anything they can think of please give me some feedback, I'm horribly confused right now. Thanks,

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  • How to output multicolumn html without "widows"?

    - by user314850
    I need to output to HTML a list of categorized links in exactly three columns of text. They must be displayed similar to columns in a newspaper or magazine. So, for example, if there are 20 lines total the first and second columns would contain 7 lines and the last column would contain 6. The list must be dynamic; it will be regularly changed. The tricky part is that the links are categorized with a title and this title cannot be a "widow". If you have a page layout background you'll know that this means the titles cannot be displayed at the bottom of the column -- they must have at least one link underneath them, otherwise they should bump to the next column (I know, technically it should be two lines if I were actually doing page layout, but in this case one is acceptable). I'm having a difficult time figuring out how to get this done. Here's an example of what I mean: Shopping Link 3 Link1 Link 1 Link 4 Link2 Link 2 Link 3 Link 3 Cars Link 1 Music Games Link 2 Link 1 Link 1 Link 2 News As you can see, the "News" title is at the bottom of the middle column, and so is a "widow". This is unacceptable. I could bump it to the next column, but that would create an unnecessarily large amount of white space at the bottom of the second column. What needs to happen instead is that the entire list needs to be re-balanced. I'm wondering if anyone has any tips for how to accomplish this, or perhaps source code or a plug in. Python is preferable, but any language is fine. I'm just trying to get the general concept down.

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  • Drupal administration theme doesn't apply to Blocks pages (admin/build/block)

    - by hfidgen
    A site I'm creating for a customer in D6 has various images overlaying parts of the main content area. It looks very pretty and they have to be there for the general effect. The problem is, if you use this theme in the administration pages, the images get in the way of everything. My solution was to create a custom admin theme, based on the default one, which has these image areas disabled in the output template files - page.tpl.php The problem is that when you try and edit the blocks page, it uses the default theme and half the blocks admin settings are unclickable behind the images. I KNOW this is by design in Drupal, but it's annoying the hell out of me and is edging towards "bug" rather than "feature" in my mind. It also appears that there is no way of getting around it. You can edit /modules/blocks/block.admin.inc to force Drupal to show the blocks page in the chosen admin theme. BUT whichever changes you then make will not be transferred to the default theme, as Drupal treats each theme separately and each theme can have different block layouts. :x function block_admin_display($theme = NULL) { global $custom_theme; // If non-default theme configuration has been selected, set the custom theme. // $custom_theme = isset($theme) ? $theme : variable_get('theme_default', 'garland'); // Display admin theme $custom_theme = variable_get('admin_theme', '0'); // Fetch and sort blocks $blocks = _block_rehash(); usort($blocks, '_block_compare'); return drupal_get_form('block_admin_display_form', $blocks, $theme); } Can anyone help? the only thing I can think of is to push the $content area well below the areas where the image appear and use blocks only for content display. Thanks!

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  • [Adobe Air] Can I catch a mouseUp event of an mx:Window that did not fire hte mouseDown?

    - by Irene
    Hi, In an AIR application, I have one mx:TileList with several images. What I need to do is let the user drag and drop one of the images on the desktop, giving a feeling of a desktop widget. Firstly I tried to implement this using dragStart etc, but in the end I think it is easier to handle mouseDown and mouseUp on the TileList. In general the whole setup works as desired. When a mouseDown is detected on the TileList, I create a transparent mx:Window containing the corresponding image, and call the startMove() on the Window to simulate a dragging behavior. If I release the mouse, the Window stops moving as desired. My problem is that now I want some visual feedback during dragging. It works while the Window is moving, however I can't find a way to stop it when the user releases the mouse. The mouseUp is not fired from the TileList, nor from the s:WindowedApplication. I also tried to add a listener to the Window itself, but still with no luck. Some code: private function onMouseDown(e:MouseEvent):void { trace ("down " + e.target); if (e.target is TileListItemRenderer) { // first create a dragWindow dragWindow.startGlow(); // then show some visual feedback dragWindow.moveWindow(e); // and start dragging } } private function onMouseUp(e:MouseEvent):void { trace("up " + e.target); dragWindow.stopGlow(); // <--------- Not called! } <mx:TileList id="photoTileList" mouseDown="onMouseDown(event)" mouseUp="onMouseUp(event)">

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  • VC++ 6 and MS Speech SDK 5.1 fatal error C1083: Cannot open source file: 'files\microsoft': No such

    - by eg123
    Trying to compile an application (flite synthesis sapi) on vc++6. This requires Microsoft Speech SDK 5.1 Have included C:\Program Files\Microsoft Speech SDK 5.1\IDL C:\Program Files\Microsoft Speech SDK 5.1\include using Toolsoptionsdirectories and also on another attempt via ProjectSettings Repeatedly get this error microsoft fatal error C1083: Cannot open source file: 'files\microsoft': No such file or directory speech fatal error C1083: Cannot open source file: 'speech': No such file or directory sdk fatal error C1083: Cannot open source file: 'sdk': No such file or directory idl fatal error C1083: Cannot open source file: '5.1\idl': No such file or directory FliteCMUKalDiphone.idl Thought it may be spaces related so included full path in quotes in relevant .h files. No joy Installed Microsoft Speech SDK 5.1 on another machine in same folder as flite and renamed to mssdk51 (so no spaces in pathname) but same error came up. Tried pasting in contents of each .idl called in file where glitch seems to generate Still same message. I am new to C++ and programming in general. My only guess is that something in the speech sdk is calling the .idl file and I can't find where from. Of course this is probably way wrong!

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  • Can a Generic Method handle both Reference and Nullable Value types?

    - by Adam Lassek
    I have a series of Extension methods to help with null-checking on IDataRecord objects, which I'm currently implementing like this: public static int? GetNullableInt32(this IDataRecord dr, int ordinal) { int? nullInt = null; return dr.IsDBNull(ordinal) ? nullInt : dr.GetInt32(ordinal); } public static int? GetNullableInt32(this IDataRecord dr, string fieldname) { int ordinal = dr.GetOrdinal(fieldname); return dr.GetNullableInt32(ordinal); } and so on, for each type I need to deal with. I'd like to reimplement these as a generic method, partly to reduce redundancy and partly to learn how to write generic methods in general. I've written this: public static Nullable<T> GetNullable<T>(this IDataRecord dr, int ordinal) { Nullable<T> nullValue = null; return dr.IsDBNull(ordinal) ? nullValue : (Nullable<T>) dr.GetValue(ordinal); } which works as long as T is a value type, but if T is a reference type it won't. This method would need to return either a Nullable type if T is a value type, and default(T) otherwise. How would I implement this behavior?

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  • protocol parsing in c

    - by nomad.alien
    I have been playing around with trying to implement some protocol decoders, but each time I run into a "simple" problem and I feel the way I am solving the problem is not optimal and there must be a better way to do things. I'm using C. Currently I'm using some canned data and reading it in as a file, but later on it would be via TCP or UDP. Here's the problem. I'm currently playing with a binary protocol at work. All fields are 8 bits long. The first field(8bits) is the packet type. So I read in the first 8 bits and using a switch/case I call a function to read in the rest of the packet as I then know the size/structure of it. BUT...some of these packets have nested packets inside them, so when I encounter that specific packet I then have to read another 8-16 bytes have another switch/case to see what the next packet type is and on and on. (Luckily the packets are only nested 2 or 3 deep). Only once I have the whole packet decoded can I handle it over to my state machine for processing. I guess this can be a more general question as well. How much data do you have to read at a time from the socket? As much as possible? As much as what is "similar" in the protocol headers? So even though this protocol is fairly basic, my code is a whole bunch of switch/case statements and I do a lot of reading from the file/socket which I feel is not optimal. My main aim is to make this decoder as fast as possible. To the more experienced people out there, is this the way to go or is there a better way which I just haven't figured out yet? Any elegant solution to this problem?

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  • How Can i Create This Complicated Query ?

    - by mTuran
    Hi, I have 3 tables: projects, skills and project_skills. In projects table i hold project's general data. Second table skills i hold skill id and skill name also i have projects_skills table which is hold project's skill relationships. Here is scheme of tables: CREATE TABLE IF NOT EXISTS `project_skills` ( `project_id` int(11) NOT NULL, `skill_id` int(11) NOT NULL, KEY `project_id` (`project_id`), KEY `skill_id` (`skill_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci; CREATE TABLE IF NOT EXISTS `projects` ( `id` int(11) NOT NULL AUTO_INCREMENT, `employer_id` int(11) NOT NULL, `project_title` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `project_description` text COLLATE utf8_turkish_ci NOT NULL, `project_budget` int(11) NOT NULL, `project_allowedtime` int(11) NOT NULL, `project_deadline` datetime NOT NULL, `total_bids` int(11) NOT NULL, `average_bid` int(11) NOT NULL, `created` datetime NOT NULL, `active` tinyint(1) NOT NULL, PRIMARY KEY (`id`), KEY `created` (`created`), KEY `employer_id` (`employer_id`), KEY `active` (`active`), FULLTEXT KEY `project_title` (`project_title`,`project_description`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=3 ; CREATE TABLE IF NOT EXISTS `skills` ( `id` int(11) NOT NULL AUTO_INCREMENT, `category` int(11) NOT NULL, `name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `seo_name` varchar(100) COLLATE utf8_turkish_ci NOT NULL, `total_projects` int(11) NOT NULL, PRIMARY KEY (`id`), KEY `seo_name` (`seo_name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_turkish_ci AUTO_INCREMENT=224 ; I want to select projects with related skill names. I think i have to use JOIN but i don't know how can i do. Thanks

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  • Hibernate 3.5.0 causes extreme performance problems

    - by user303396
    I've recently updated from hibernate 3.3.1.GA to hibernate 3.5.0 and I'm having a lot of performance issues. As a test, I added around 8000 entities to my DB (which in turn cause other entities to be saved). These entities are saved in batches of 20 so that the transactions aren't too large for performance reasons. When using hibernate 3.3.1.GA all 8000 entities get saved in about 3 minutes. When using hibernate 3.5.0 it starts out slower than with hibernate 3.3.1. But it gets slower and slower. At around 4,000 entities, it sometimes takes 5 minutes just to save a batch of 20. If I then go to a mysql console and manually type in an insert statement from the mysql general query log, half of them run perfect in 0.00 seconds. And half of them take a long time (maybe 40 seconds) or timeout with "ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction" from MySQL. Has something changed in hibernate's transaction management in version 3.5.0 that I should be aware of? The ONLY thing I changed to experience these unusable performance issues is replace the following hibernate 3.3.1.GA jar files: com.springsource.org.hibernate-3.3.1.GA.jar, com.springsource.org.hibernate.annotations-3.4.0.GA.jar, com.springsource.org.hibernate.annotations.common-3.3.0.ga.jar, com.springsource.javassist-3.3.0.ga.jar with the new hibernate 3.5.0 release hibernate3.jar and javassist-3.9.0.GA.jar. Thanks.

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  • Visual Studio and .NET programming

    - by Vit
    Hi, I just want to ask wheather I am right or not about .NET. So, .NET is new framework that enables you to easily implement new and old windows functions. It is similiar to java in the way that its also compiled into "bytecode", but its name is Common Language Infrastructure, or CLI. This language is interpreted by .NET Framework, so code generated by programming using .NET cannot be executed directly by CPU. Now, few languages can be compiled to CLI. First, it was Microsoft-developed C#, than J#, C++ others. I suspect that this is in general right, at least I hope I understand it right. But, what I am still missing is, can you write to machine code compiled code in C#? And, if using Visual Studio 2005, when I select Win32 project, it is compiled into machine code, so only thing you need to run this apps are windows dynamic-link libraries, since static libraries code is implemented into app durink linking phase. And those dynamic-link libraries are implemented in every windows installation, or provided by DirectX installations. But when I select CLR in Visual Studio 2005, than app is compiled into CLI code, and it first executes .NET framework, and than .NET framework executes that program, since its not in machine code. So, I am right? I ask becouse you can read these infos on the internet, but I have noone to tell me wheather I understand it right or not. Thanks.

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  • linear combinations in python/numpy

    - by nmaxwell
    greetings, I'm not sure if this is a dumb question or not. Lets say I have 3 numpy arrays, A1,A2,A3, and 3 floats, c1,c2,c3 and I'd like to evaluate B = A1*c1+ A2*c2+ A3*c3 will numpy compute this as for example, E1 = A1*c1 E2 = A2*c2 E3 = A3*c3 D1 = E1+E2 B = D1+E3 or is it more clever than that? In c++ I had a neat way to abstract this kind of operation. I defined series of general 'LC' template functions, LC for linear combination like: template<class T,class D> void LC( T & R, T & L0,D C0, T & L1,D C1, T & L2,D C2) { R = L0*C0 +L1*C1 +L2*C2; } and then specialized this for various types, so for instance, for an array the code looked like for (int i=0; i<L0.length; i++) R.array[i] = L0.array[i]*C0 + L1.array[i]*C1 + L2.array[i]*C2; thus avoiding having to create new intermediate arrays. This may look messy but it worked really well. I could do something similar in python, but I'm not sure if its nescesary. Thanks in advance for any insight. -nick

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  • Which pdf elements could cause crashes?

    - by Felixyz
    This is a very general question but it's based on a specific problem. I've created a pdf reader app for the iPad and it works fine except for certain pdf pages which always crash the app. We now found out that the very same pages cause Safari to crash as well, so as I had started to suspect the problem is somewhere in Apple's pdf rendering code. From what I have been able to see, the crashing pages cause the rendering libraries to start allocating memory like mad until the app is killed. I have nothing else to help me pinpoint what triggers this process. It doesn't necessarily happen with the largest documents, or the ones with the most shapes. In fact, we haven't found any parameter that helps us predict which pages will crash and which not. Now we just discovered that running the pages through a consumer program that lets you merge docs gets rid of the problem, but I haven't been able to detect which attribute or element it is that is the key. Changing documents by hand is also not an option for us in the long run. We need to run an automated process on our server. I'm hoping someone with deeper knowledge about the pdf file format would be able to point me in a reasonable direction to look for document features that could cause this kind of behavior. All I've found so far is something about JBIG2 images, and I don't think we have any of those.

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