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  • How do you pass an enum by reference?

    - by Darkenor
    I have an enum with four keys I'm taking as input for an interface program and I'd like to pass the enum by value to the interface function, which has become quite long. The enum is like this: enum MYKEYS { W, S, O, L }; There's also a boolean array that I have to pass by reference, which is also a little tricky. bool key[4] = { false, false, false, false }; Does anyone know the proper syntax to pass both of these as reference in a function, similar to: function(int & anintreference);

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  • How to use dd to make splitted ISO images from an storage device?

    - by Gustavo Bandeira
    This is a double question, I just hope it's valid. I need to know how to use dd to make splitted ISO images from some storage device, I'm doing it through SSH: the process is slow and the risk of faling at the mid of the operation (1) is high then I need to know how to make these splitted ISO images from my storage device. (2) I'm searching for some reference on dd, it could be a book or a good website about it for when any doubt arises. 1 - I'm doing it on a ~60GB storage device, it took me a whole day to copy ~10GB from this disk. 2 - For curious people, I'm trying to recover an accidentaly deleted file from an iPod, until now I've been able to make the whole process, I just need to improve it beucase I left it copying the disk yesterday: Today it gave me an error when it was at ~10GB.

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  • httpd keeps crashing without any reference to why in the logs

    - by Fred
    I have the logs set to debug in the hopes of tracking down what's causing the crash, but I can't find anything. Here is the error_log. [Thu Jan 06 10:27:35 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 19999 for (*) [Thu Jan 06 14:47:04 2011] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Thu Jan 06 14:47:04 2011] [info] Init: Seeding PRNG with 256 bytes of entropy [Thu Jan 06 14:47:04 2011] [info] Init: Generating temporary RSA private keys (512/1024 bits) [Thu Jan 06 14:47:04 2011] [info] Init: Generating temporary DH parameters (512/1024 bits) [Thu Jan 06 14:47:04 2011] [info] Init: Initializing (virtual) servers for SSL [Thu Jan 06 14:47:04 2011] [info] Server: Apache/2.2.3, Interface: mod_ssl/2.2.3, Library: OpenSSL/0.9.8e-fips-rhel5 [Thu Jan 06 14:47:04 2011] [notice] Digest: generating secret for digest authentication ... [Thu Jan 06 14:47:04 2011] [notice] Digest: done [Thu Jan 06 14:47:04 2011] [debug] util_ldap.c(2021): LDAP merging Shared Cache conf: shm=0xb9dc2480 rmm=0xb9dc24b0 for VHOST: server.fredfinn.com [Thu Jan 06 14:47:04 2011] [info] APR LDAP: Built with OpenLDAP LDAP SDK [Thu Jan 06 14:47:04 2011] [info] LDAP: SSL support available [Thu Jan 06 14:47:05 2011] [info] Init: Seeding PRNG with 256 bytes of entropy [Thu Jan 06 14:47:05 2011] [info] Init: Generating temporary RSA private keys (512/1024 bits) [Thu Jan 06 14:47:05 2011] [info] Init: Generating temporary DH parameters (512/1024 bits) [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(374): shmcb_init allocated 512000 bytes of shared memory [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(554): entered shmcb_init_memory() [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(576): for 512000 bytes, recommending 4266 indexes [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(619): shmcb_init_memory choices follow [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(621): division_mask = 0x1F [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(623): division_offset = 64 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(625): division_size = 15998 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(627): queue_size = 1604 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(629): index_num = 133 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(631): index_offset = 8 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(633): index_size = 12 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(635): cache_data_offset = 8 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(637): cache_data_size = 14386 [Thu Jan 06 14:47:05 2011] [debug] ssl_scache_shmcb.c(650): leaving shmcb_init_memory() [Thu Jan 06 14:47:05 2011] [info] Shared memory session cache initialised [Thu Jan 06 14:47:05 2011] [info] Init: Initializing (virtual) servers for SSL [Thu Jan 06 14:47:05 2011] [info] Server: Apache/2.2.3, Interface: mod_ssl/2.2.3, Library: OpenSSL/0.9.8e-fips-rhel5 [Thu Jan 06 14:47:05 2011] [warn] pid file /etc/httpd/run/httpd.pid overwritten -- Unclean shutdown of previous Apache run? [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26527 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26527 for (*) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26528 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26528 for (*) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26529 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26529 for (*) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26530 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26530 for (*) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26532 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26532 for (*) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26533 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26533 for (*) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26534 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26534 for (*) [Thu Jan 06 14:47:05 2011] [notice] Apache/2.2.3 (CentOS) configured -- resuming normal operations [Thu Jan 06 14:47:05 2011] [info] Server built: Aug 30 2010 12:32:08 [Thu Jan 06 14:47:05 2011] [debug] prefork.c(991): AcceptMutex: sysvsem (default: sysvsem) [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1854): proxy: grabbed scoreboard slot 0 in child 26531 for worker proxy:reverse [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1873): proxy: worker proxy:reverse already initialized [Thu Jan 06 14:47:05 2011] [debug] proxy_util.c(1967): proxy: initialized single connection worker 0 in child 26531 for (*) The logs are setup as: ErrorLog logs/error_log LogLevel debug LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent CustomLog logs/access_log common CustomLog logs/access_log combined ServerSignature On

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  • Excel - Filling images using a reference image

    - by tjans
    I have a spreadsheet that I use to create baseball cards for a tabletop baseball game. There are about 20 cards on my sheet, and I'd like to add a spot where I can set the logo and have it reflect that logo in each card without having to update 20 different images each time I create cards for a new team (and thus, a new logo). Is there a way to automate this process similar to setting one cell equal to the value of another (=A4, for instance)? I think the images aren't part of a cell and they float on top of the sheet, but I had hoped there was a way either with a macro or other VBA function (or maybe something built-in) that would accomplish this.

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  • Excel 2007 How To Reference A Seperate Cell In WS1 From A Common Cell In WS2

    - by Bob Sampson
    I have a simple file with two worksheets in. In the first worksheet (a product list) are a number of columns, including Product Code and Product Description. In the second worksheet (dispatches in January), I have Product Code. I need to insert a new column with the associated Product Description field completed based on the relevant line from the first worksheet. I'm sure this is very easy, but its not something I've done before. Thank you

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  • Numbering equations based on chapter numbers in MS-Word

    - by Isaac
    I am seeking for a way to number each equation based on the chapter numbers. The number should be placed at the right side of the equation and the equation should be center-aligned. Something like this: (The bounding box around 2.3 is not necessary). I found this article that do this in a tricky way. Sadly it has some problems when I use multilevel numbering for Headings. To conclude, I am looking for a way to numbers equations that: The numbering is formatted as N-M that N is chapter number and M is equation number. equation is placed in center-aligned number is placed in the right side of equation There should be a way to cross-reference each numbered equation. Thanks!

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  • Gnome, open with, custom command, filename reference

    - by Tergiver
    I want to execute this custom command on a file from the Gnome File Browser: hexdump -C $f > $f.dump That would create a hexdump of the file with the file's name + .dump in the directory that the file exists in. When I say $f above I mean something that would substitute the name of the file that was opened. So I've tried "Open with", "Use a custom command". I can't get it to work. I've tried a number of symbols in place of $f. Is it even possible? Before you suggest getting a GUI hexdump program, this is just one example. I have the need to do this sort of thing for many terminal-type programs. Am I the only person on Earth who wishes for a hybrid File-Browser-slash-Command-Terminal? That would be a file browser which contained a terminal pane who's current directory always matched that of the file browser. One could execute shell commands in the context of what they were viewing in the browser.

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  • How can I create a macro that acts on a relative reference rather than an absolute reference to cell A1?

    - by Bruce
    I have a master rent statement in an Excel 2007 (macro enabled) spreadsheet that shows all tenants in rows with columns formed by the months. Each tenant then has a separate rent statement sheet like the one below that pulls the data through from the master rent statement and all I do then is to copy the last 4 columns to the right and add them to the right, just renaming the month labelled as ‘rent due’ with the current month and then hiding the previous last 4 columns to the left so that the statement always shows the previous month's activity and the amount due for the current month: I used a macro to speed up the creation of these statements, but then found that in some cases the result was wrong and needed major correction because the macro use absolute references i.e. its starting position was relative to cell A1 whereas some of my rent worksheets commence from a different column and in some cases from a different column and a different row. I have tried recording the macro with 'Use relative references' but when trying to use the macro it only gets part way through its operation before it stops and the message appears: Run time error '1004' Application defined or object defined error with the option to End or Debug or go to Help and then I'm stuck as I don't know how to debug and work in VBA or understand what has gone wrong. I want to record a single macro that always remains relative to the last 'Total Due' column heading (in the sample, it’s cell FF3 but on another worksheet could be cell GA26) and thus enables me regardless of where on the worksheet the rent statement is placed to add through my recorded macro a further four columns with updated dates and a repositioned 'Total Due' summary (in the sample in cells FE23 and FF23). The contents of cells FE23 and FE22 are always the same number of rows from the 'Sample Rent Statement, Service Charge and Sub Total' rows. I've searched on the web and in the help files of Excel 2007 but have been totally stumped by this, so currently I have to re-record a quantity of macros each month to cover all of the permutations of the worksheets in my Excel rent workbook, which is starting to become pointless in terms of saving time. Does someone know a solution to this problem please?!

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  • Windows batch file reference to own directory

    - by rwallace
    Suppose you have C:\foo\foo.bat which needs to refer to C:\foo\foo.txt. It may be run from a different directory, but needs to get foo.txt from its own directory, not the current directory. Obviously this could be done by putting the full path C:\foo\foo.txt in foo.bat. The twist is, it's not known at the time of writing the batch file, where it will end up residing on the user's machine, so what the batch file actually needs to do is get foo.txt from the directory where I live, wherever that happens to be. (In a C program I'd use argv[0] but that doesn't seem to work with batch files.) Is there a way to do this?

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  • JS: using 'var me = this' to reference an object instead of using a global array

    - by Marco Demaio
    The example below, is just an example, I know that I don't need an object to show an alert box when user clicks on div blocks, but it's just a simple example to explain a situation that frequently happens when writing JS code. In the example below I use a globally visible array of objects to keep a reference to each new created HelloObject, in this way events called when clicking on a div block can use the reference in the arry to call the HelloObject's public function hello(). 1st have a look at the code: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html><head><meta http-equiv="Content-Type" content="text/html; charset=windows-1252"> <title>Test </title> <script type="text/javascript"> /***************************************************** Just a cross browser append event function, don't need to understand this one to answer my question *****************************************************/ function AppendEvent(html_element, event_name, event_function) {if(html_element) {if(html_element.attachEvent) html_element.attachEvent("on" + event_name, event_function); else if(html_element.addEventListener) html_element.addEventListener(event_name, event_function, false); }} /****************************************************** Just a test object ******************************************************/ var helloobjs = []; var HelloObject = function HelloObject(div_container) { //Adding this object in helloobjs array var id = helloobjs.length; helloobjs[id] = this; //Appending click event to show the hello window AppendEvent(div_container, 'click', function() { helloobjs[id].hello(); //THIS WORKS! }); /***************************************************/ this.hello = function() { alert('hello'); } } </script> </head><body> <div id="one">click me</div> <div id="two">click me</div> <script type="text/javascript"> var t = new HelloObject(document.getElementById('one')); var t = new HelloObject(document.getElementById('two')); </script> </body></html> In order to achive the same result I could simply replace the code //Appending click event to show the hello window AppendEvent(div_container, 'click', function() { helloobjs[id].hello(); //THIS WORKS! }); with this code: //Appending click event to show the hello window var me = this; AppendEvent(div_container, 'click', function() { me.hello(); //THIS WORKS TOO AND THE GLOBAL helloobjs ARRAY BECOMES SUPEFLOUS! }); thus would make the helloobjs array superflous. My question is: does this 2nd option in your opinion create memoy leaks on IE or strange cicular references that might lead to browsers going slow or to break??? I don't know how to explain, but coming from a background as a C/C++ coder, doing in this 2nd way sounds like a some sort of circular reference that might break memory at some point. I also read on internet about the IE closures memory leak issue http://jibbering.com/faq/faq_notes/closures.html (I don't know if it was fixed in IE7 and if yes, I hope it does not come out again in IE8). Thanks

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  • Building an HTML5 App with ASP.NET

    - by Stephen Walther
    I’m teaching several JavaScript and ASP.NET workshops over the next couple of months (thanks everyone!) and I thought it would be useful for my students to have a really easy to use JavaScript reference. I wanted a simple interactive JavaScript reference and I could not find one so I decided to put together one of my own. I decided to use the latest features of JavaScript, HTML5 and jQuery such as local storage, offline manifests, and jQuery templates. What could be more appropriate than building a JavaScript Reference with JavaScript? You can try out the application by visiting: http://Superexpert.com/JavaScriptReference Because the app takes advantage of several advanced features of HTML5, it won’t work with Internet Explorer 6 (but really, you should stop using that browser). I have tested it with IE 8, Chrome 8, Firefox 3.6, and Safari 5. You can download the source for the JavaScript Reference application at the end of this article. Superexpert JavaScript Reference Let me provide you with a brief walkthrough of the app. When you first open the application, you see the following lookup screen: As you type the name of something from the JavaScript language, matching results are displayed: You can click the details link for any entry to view details for an entry in a modal dialog: Alternatively, you can click on any of the tabs -- Objects, Functions, Properties, Statements, Operators, Comments, or Directives -- to filter results by type of syntax. For example, you might want to see a list of all JavaScript built-in objects: You can login to the application to make modification to the application: After you login, you can add, update, or delete entries in the reference database: HTML5 Local Storage The application takes advantage of HTML5 local storage to store all of the reference entries on the local browser. IE 8, Chrome 8, Firefox 3.6, and Safari 5 all support local storage. When you open the application for the first time, all of the reference entries are transferred to the browser. The data is stored persistently. Even if you shutdown your computer and return to the application many days later, the data does not need to be transferred again. Whenever you open the application, the app checks with the server to see if any of the entries have been updated on the server. If there have been updates, then only the updates are transferred to the browser and the updates are merged with the existing entries in local storage. After the reference database has been transferred to your browser once, only changes are transferred in the future. You get two benefits from using local storage. First, the application loads very fast and works very fast after the data has been loaded once. The application does not query the server whenever you filter or view entries. All of the data is persisted in the browser. Second, you can browse the JavaScript reference even when you are not connected to the Internet (when you are on the proverbial airplane). The JavaScript Reference works as an offline application for browsers that support offline applications (unfortunately, not IE). When using Google Chrome, you can easily view the contents of local storage by selecting Tools, Developer Tools (CTRL-SHIFT I) and selecting Storage, Local Storage: The JavaScript Reference app stores two items in local storage: entriesLastUpdated and entries. HTML5 Offline App For browsers that support HTML5 offline applications – Chrome 8 and Firefox 3.6 but not Internet Explorer – you do not need to be connected to the Internet to use the JavaScript Reference. The JavaScript Reference can execute entirely on your machine just like any other desktop application. When you first open the application with Firefox, you are presented with the following warning: Notice the notification bar that asks whether you want to accept offline content. If you click the Allow button then all of the files (generated ASPX, images, CSS, JavaScript) needed for the JavaScript Reference will be stored on your local computer. Automatic Script Minification and Combination All of the custom JavaScript files are combined and minified automatically whenever the application is built with Visual Studio. All of the custom scripts are contained in a folder named App_Scripts: When you perform a build, the combine.js and combine.debug.js files are generated. The Combine.config file contains the list of files that should be combined (importantly, it specifies the order in which the files should be combined). Here’s the contents of the Combine.config file:   <?xml version="1.0"?> <combine> <scripts> <file path="compat.js" /> <file path="storage.js" /> <file path="serverData.js" /> <file path="entriesHelper.js" /> <file path="authentication.js" /> <file path="default.js" /> </scripts> </combine>   jQuery and jQuery UI The JavaScript Reference application takes heavy advantage of jQuery and jQuery UI. In particular, the application uses jQuery templates to format and display the reference entries. Each of the separate templates is stored in a separate ASP.NET user control in a folder named Templates: The contents of the user controls (and therefore the templates) are combined in the default.aspx page: <!-- Templates --> <user:EntryTemplate runat="server" /> <user:EntryDetailsTemplate runat="server" /> <user:BrowsersTemplate runat="server" /> <user:EditEntryTemplate runat="server" /> <user:EntryDetailsCloudTemplate runat="server" /> When the default.aspx page is requested, all of the templates are retrieved in a single page. WCF Data Services The JavaScript Reference application uses WCF Data Services to retrieve and modify database data. The application exposes a server-side WCF Data Service named EntryService.svc that supports querying, adding, updating, and deleting entries. jQuery Ajax calls are made against the WCF Data Service to perform the database operations from the browser. The OData protocol makes this easy. Authentication is handled on the server with a ChangeInterceptor. Only authenticated users are allowed to update the JavaScript Reference entry database. JavaScript Unit Tests In order to build the JavaScript Reference application, I depended on JavaScript unit tests. I needed the unit tests, in particular, to write the JavaScript merge functions which merge entry change sets from the server with existing entries in browser local storage. In order for unit tests to be useful, they need to run fast. I ran my unit tests after each build. For this reason, I did not want to run the unit tests within the context of a browser. Instead, I ran the unit tests using server-side JavaScript (the Microsoft Script Control). The source code that you can download at the end of this blog entry includes a project named JavaScriptReference.UnitTests that contains all of the JavaScripts unit tests. JavaScript Integration Tests Because not every feature of an application can be tested by unit tests, the JavaScript Reference application also includes integration tests. I wrote the integration tests using Selenium RC in combination with ASP.NET Unit Tests. The Selenium tests run against all of the target browsers for the JavaScript Reference application: IE 8, Chrome 8, Firefox 3.6, and Safari 5. For example, here is the Selenium test that checks whether authenticating with a valid user name and password correctly switches the application to Admin Mode: [TestMethod] [HostType("ASP.NET")] [UrlToTest("http://localhost:26303/JavaScriptReference")] [AspNetDevelopmentServerHost(@"C:\Users\Stephen\Documents\Repos\JavaScriptReference\JavaScriptReference\JavaScriptReference", "/JavaScriptReference")] public void TestValidLogin() { // Run test for each controller foreach (var controller in this.Controllers) { var selenium = controller.Value; var browserName = controller.Key; // Open reference page. selenium.Open("http://localhost:26303/JavaScriptReference/default.aspx"); // Click login button displays login form selenium.Click("btnLogin"); Assert.IsTrue(selenium.IsVisible("loginForm"), "Login form appears after clicking btnLogin"); // Enter user name and password selenium.Type("userName", "Admin"); selenium.Type("password", "secret"); selenium.Click("btnDoLogin"); // Should set adminMode == true selenium.WaitForCondition("selenium.browserbot.getCurrentWindow().adminMode==true", "30000"); } }   The results for running the Selenium tests appear in the Test Results window just like the unit tests: The Selenium tests take much longer to execute than the unit tests. However, they provide test coverage for actual browsers. Furthermore, if you are using Visual Studio ALM, you can run the tests automatically every night as part of your standard nightly build. You can view the Selenium tests by opening the JavaScriptReference.QATests project. Summary I plan to write more detailed blog entries about this application over the next week. I want to discuss each of the features – HTML5 local storage, HTML5 offline apps, jQuery templates, automatic script combining and minification, JavaScript unit tests, Selenium tests -- in more detail. You can download the source control for the JavaScript Reference Application by clicking the following link: Download You need Visual Studio 2010 and ASP.NET 4 to build the application. Before running the JavaScript unit tests, install the Microsoft Script Control. Before running the Selenium tests, start the Selenium server by running the StartSeleniumServer.bat file located in the JavaScriptReference.QATests project.

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  • What are the best Perl Introductions and references?

    - by Kieveli
    I've been programming for 15+ years, and I've done perl programming 3 times in the past. Every time I come back to it, I remember nothing of the language. It's very bizarre. Now it's time to hit perl again, and I'm wondering what the best Intro / Reference / Best Practice sites are that people use. Which Perl Intro / Reference site do you recommend?

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  • Some clarification on rvalue references

    - by Dennis Zickefoose
    First: where are std::move and std::forward defined? I know what they do, but I can't find proof that any standard header is required to include them. In gcc44 sometimes std::move is available, and sometimes its not, so a definitive include directive would be useful. When implementing move semantics, the source is presumably left in an undefined state. Should this state necessarily be a valid state for the object? Obviously, you need to be able to call the object's destructor, and be able to assign to it by whatever means the class exposes. But should other operations be valid? I suppose what I'm asking is, if your class guarantees certain invariants, should you strive to enforce those invariants when the user has said they don't care about them anymore? Next: when you don't care about move semantics, are there any limitations that would cause a non-const reference to be preferred over an rvalue reference when dealing with function parameters? void function(T&); over void function(T&&); From a caller's perspective, being able to pass functions temporary values is occasionally useful, so it seems as though one should grant that option whenever it is feasible to do so. And rvalue references are themselves lvalues, so you can't inadvertently call a move-constructor instead of a copy-constructor, or something like that. I don't see a downside, but I'm sure there is one. Which brings me to my final question. You still can not bind temporaries to non-const references. But you can bind them to non-const rvalue references. And you can then pass along that reference as a non-const reference in another function. void function1(int& r) { r++; } void function2(int&& r) { function1(r); } int main() { function1(5); //bad function2(5); //good } Besides the fact that it doesn't do anything, is there anything wrong with that code? My gut says of course not, since changing rvalue references is kind of the whole point to their existence. And if the passed value is legitimately const, the compiler will catch it and yell at you. But by all appearances, this is a runaround of a mechanism that was presumably put in place for a reason, so I'd just like confirmation that I'm not doing anything foolish.

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  • Why do some people prefer "T const&" over "const T&"?

    - by Michael Aaron Safyan
    So, I realize that const T& and T const& are identical and both mean a reference to a const T. In both cases, the reference is also constant (references cannot be reassigned, unlike pointers). I've observed, in my somewhat limited experience, that most C++ programmers use const T&, but I have come across a few people who use T const&. Is this just a personal preference? Why is one chosen over the other?

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  • How to pass objects to functions in C++?

    - by Rakesh K
    I am new to C++ programming, but I have experience in Java. I need guidance on how to pass objects to functions in C++. Do I need to pass pointers, references, or non-pointer and non-reference values? I remember in Java there are no such issues since we pass just the variable that holds reference to the objects. It would be great if you could also explain where to use each of those options.

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  • The endpoint reference (EPR) for the Operation not found is

    - by Denise Wu
    I have been struggling with the following error the last couple of days can you please help! I generated my server and client code using the wsdl2java tool from a wsdl 2.0 file. When invoking the webservice I am getting the following error: org.apache.axis2.AxisFault: The endpoint reference (EPR) for the Operation not found is /axis2/services/MyService/authentication/?username=Denise345&password=xxxxx and the WSA Action = null My service is displayed on the axis2 webpage with all available methods. Here is the output from TcpMon ============== Listen Port: 8090 Target Host: 127.0.0.1 Target Port: 8080 ==== Request ==== GET /axis2/services/MyService/authentication/?username=Denise345&password=xxxxx HTTP/1.1 Content-Type: application/x-www-form-urlencoded; charset=UTF-8 SOAPAction: "" User-Agent: Axis2 Host: 127.0.0.1:8090 ==== Response ==== HTTP/1.1 500 Internal Server Error Server: Apache-Coyote/1.1 Content-Type: application/xml;charset=UTF-8 Transfer-Encoding: chunked Date: Thu, 12 May 2011 15:53:20 GMT Connection: close 12b <soapenv:Reason xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope"> <soapenv:Text xml:lang="en-US">The endpoint reference (EPR) for the Operation not found is /axis2/services/MyService/authentication/?username=Denise345&password=xxxxx and the WSA Action = null</soapenv:Text></soapenv:Reason> 0 ============== I am using: * axis2-1.5.4 * Tomcat 7.0.8 * wsdl 2.0 file Please help!

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  • Null Reference getting REMOTE_ADDR

    - by Josh
    I have an ASMX web service running under IIS7 in classic mode. This service has the following code: try { env.ExternalIP = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]; } catch (Exception ex) { LogWriter.WriteError(ex); env.ExternalIP="000.000.000.000"; } This results in the following stack trace. I only modified the names of usercode call stack here to protect the innocent: Message: An Exception of type: NullReferenceException occured in method: GetAdditionalServerVar ExceptionMsg: Object reference not set to an instance of an object. ===Stack Trace=== at System.Web.Hosting.ISAPIWorkerRequestInProc.GetAdditionalServerVar(Int32 index) at System.Web.Hosting.ISAPIWorkerRequestInProc.GetServerVariable(String name) at System.Web.HttpRequest.AddServerVariableToCollection(String name) at System.Web.HttpRequest.FillInServerVariablesCollection() at System.Web.HttpServerVarsCollection.Populate() at System.Web.HttpServerVarsCollection.Get(String name) at System.Collections.Specialized.NameValueCollection.get_Item(String name) at MyService.MyMethod() I'm at a loss here as this is very basic plain vanilla code. EDIT This gets even stranger. I have added some basic code just wondering what server variables I can get at this point. This fails with the same exception when I try and get all the keys: System.NullReferenceException: Object reference not set to an instance of an object. at System.Web.Hosting.ISAPIWorkerRequestInProc.GetAdditionalServerVar(Int32 index) at System.Web.Hosting.ISAPIWorkerRequestInProc.GetServerVariable(String name) at System.Web.HttpRequest.AddServerVariableToCollection(String name) at System.Web.HttpRequest.FillInServerVariablesCollection() at System.Web.HttpServerVarsCollection.Populate() at System.Web.HttpServerVarsCollection.get_AllKeys() at MyService.MyHelper() When I was looking at the framework code looks like this could happen when the array which caches the server variables isn't populated and it looks like this occurs when there a null pointer to some Context...which seems like a fairly core piece of the framework code. I suppose it's time to burn up one of our support tickets with Microsoft.

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  • Pass WPF UserControl reference to another UserControl

    - by Rob Bell
    I've created two UserControls, a ValidationManager and a ValidationOutput. On a given form there is one ValidationManager and several ValidationOutput controls, one for each control that is validated. The ValidationManager is given a list of validation errors when the form is submitted, I want each ValidationOutput control to look at this list and see if there are any errors relevant to them. The code looks a bit like this: <r:ValidationManager x:Name="myValidationManager" /> ... <TextBox Name="SomeField" /> <r:ValidationOutput FieldName="SomeField" /> I need to pass a reference to the ValidationManager to each of the ValidationOutput controls. I've added a ValidationManager property to the ValidationOutput UserControl but don't know how to pass the reference to the control. I've tried the following but am just clutching at straws: <r:ValidationOutput ValidationManager="myValidationManager" /> ...and... <r:ValidationOutput ValidationManager="{Binding myValidationManager}" /> The first results in an error "Property 'ValidationManager' was not found or is not serializable for type 'ValidationOutput'" and the second "A 'Binding' cannot be set on the 'ValidationManager' property of type 'ValidationControl'. A 'Binding' can only be set on a DependencyProperty of a DependencyObject."

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  • Problem compiling gnustep-gui-0.16.0 undefined reference to png_sizeof

    - by stefanB
    I'm trying to compile GNUstep on a linux box but gnustep-gui-0.16.0 package is failing. I downloaded GNUstep Startup stable 0.20.1 (http://wwwmain.gnustep.org/resources/downloads.php)and follow instructions about how to compile (./configure && make). I'm getting this error: libgnustep-gui.so: undefined reference to 'png_sizeof' I have compiled latest libpng (1.2.34) and I can see that png_sizeof is defined as macro. However, I'm not quite sure how to fix the gnustep-gui-0.16.0 build. I tried to pass the include/lib directory where libpng is installed to configure build but nothing seems to help. I have quite up to date linux box but using gcc 3.3 (upgrade is not an option - but this should not be a problem). Full error: Making all for tool set_show_service... Compiling file set_show_service.m ... Linking tool set_show_service ... ../Source/./obj/libgnustep-gui.so: undefined reference to `png_sizeof' collect2: ld returned 1 exit status gmake[3]: *** [obj/set_show_service] Error 1 gmake[2]: *** [set_show_service.all.tool.variables] Error 2 gmake[1]: *** [internal-all] Error 2 gmake[1]: Leaving directory `/home/bla/local/src/gnustep-startup-0.22.0/build/gnustep-gui-0.16.0' gmake[3]: *** [obj/set_show_service] Error 1 gmake[2]: *** [set_show_service.all.tool.variables] Error 2 gmake[1]: *** [internal-all] Error 2 Any suggestions? Thanks

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  • WPF - How to properly reference a class from XAML

    - by Andy T
    OK, this is a super super noob question, one that I'm almost embarrassed to ask... I want to reference a class in my XAML file. It's a DataTemplateSelector for selecting the right edit template for a DataGrid column. Anyway, I've written the class into my code behind, added the local namespace to the top of top of the XAML, but when I try to reference the class from the XAML, it tells me the class does not exist in the local namespace. I must be missing something really really simple but I just can't understand it... Here's my code. XAML: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:tk="http://schemas.microsoft.com/wpf/2008/toolkit" xmlns:local="clr-namespace:CustomFields" xmlns:col="clr-namespace:System.Collections;assembly=mscorlib" xmlns:sys="clr-namespace:System;assembly=mscorlib" x:Class="CustomFields.MainWindow" x:Name="Window" Title="Define Custom Fields" Width="425" Height="400" MinWidth="425" MinHeight="400"> <Window.Resources> <ResourceDictionary> <local:RangeValuesEditTemplateSelector> blah blah blah... </local:RangeValuesEditTemplateSelector> </ResourceDictionary> </Window.Resources> C#: namespace CustomFields { /// /// Interaction logic for MainWindow.xaml /// public partial class MainWindow : Window { public MainWindow() { this.InitializeComponent(); // Insert code required on object creation below this point. } } public class RangeValuesEditTemplateSelector : DataTemplateSelector { public RangeValuesEditTemplateSelector(){ MessageBox.Show("hello"); } } } Any ideas what I'm doing wrong? I thought this should be simple as 1-2-3... Thanks! AT

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