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• Atomic operations on several transactionless external systems

  - by simendsjo

  Say you have an application connecting 3 different external systems. You need to update something in all 3. In case of a failure, you need to roll back the operations. This is not a hard thing to implement, but say operation 3 fails, and when rolling back, the rollback for operation 1 fails! Now the first external system is in an invalid state... I'm thinking a possible solution is to shut down the application and forcing a manual fix of the external system, but then again... It might already have used this information (and perhaps that's why it failed), or we might not have sufficient access. Or it might not even be a good way to rollback the action! Are there some good ways of handling such cases? EDIT: Some application details.. It's a multi user web application. Most of the work is done with scheduled jobs (through Quartz.Net), so most operations is run in it's own thread. Some user actions should trigger jobs that update several systems though. The external systems are somewhat unstable. I Was thinking of changing the application to use the Command and Unit Of Work pattern

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• How to: StructureMap and configuration based on runtime parameters?

  - by user981375

  In a nutshell - I want to be able to instantiate object based on runtime parameters. In this particular case there are only two parameters but the problem is that I'm facing different permutations of these parameters and it gets messy. Here is the situation: I want to get an instance of an object specific to, say, given country and then, say, specific state/province. So, considering the US, there are 50 possible combinations. In reality it's less than that but that's the max. Think of it this way, I want to find out what's the penalty for smoking pot in a given country/state, I pass this information in and I get instantiated object telling me what it is. To the code (for reference only): interface IState { string Penalty { get; } } interface ICountry { IState State { get; set; } string Name { get; } } class BasePenalty : IState { virtual public string Penalty { get { return "Slap on a wrist"; } } } class USA : ICountry { public USA(IState state) { State = state; } public IState State { get; set; } public string Name { get { return "USA"; } } } class Florida: BasePenalty { public override string Penalty { get { return "Public beheading"; } } } // and so on ... I defined other states // which have penalties other than the "Slap on a wrist" How do I configure my container that when given country and state combination it will return the penalty? I tried combinations of profile and contextual binding but that configuration was directly proportional to the number of classes I've created. I have already gone thru trouble of defining different combinations. I'd like to avoid having to do the same during container configuration. I want to inject State into the Country. Also, I'd like to return UsaBasePenalty value in case state is not specified. Is that possible? Perhaps these is something wrong with the design.

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• Omit return type in C++0x

  - by Clinton

  I've recently found myself using the following macro with gcc 4.5 in C++0x mode: #define RETURN(x) -> decltype(x) { return x; } And writing functions like this: template <class T> auto f(T&& x) RETURN (( g(h(std::forward<T>(x))) )) I've been doing this to avoid the inconvenience having to effectively write the function body twice, and having keep changes in the body and the return type in sync (which in my opinion is a disaster waiting to happen). The problem is that this technique only works on one line functions. So when I have something like this (convoluted example): template <class T> auto f(T&& x) -> ... { auto y1 = f(x); auto y2 = h(y1, g1(x)); auto y3 = h(y1, g2(x)); if (y1) { ++y3; } return h2(y2, y3); } Then I have to put something horrible in the return type. Furthermore, whenever I update the function, I'll need to change the return type, and if I don't change it correctly, I'll get a compile error if I'm lucky, or a runtime bug in the worse case. Having to copy and paste changes to two locations and keep them in sync I feel is not good practice. And I can't think of a situation where I'd want an implicit cast on return instead of an explicit cast. Surely there is a way to ask the compiler to deduce this information. What is the point of the compiler keeping it a secret? I thought C++0x was designed so such duplication would not be required.

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• PHP Notice: Undefined index when looping array...

  - by Jonathan

  Hi, I'm looping a two-dimensional array like this: if (!empty($aka)) { foreach ($aka as $ak) { if($ak["lang"]=="es") { $sptitle=$ak["title"]; } } } Pretty simple. If the array ($aka) is not empty I loop trough it and when it finds that the "lang" index is equal to "es" I just save the "title" value for that index in $sptitle. The problem is that the array ($aka) contains a lot of information and sometimes there is no "lang" index... and I get this error: Notice: Undefined index: lang. How can I fix this??? This is a extract of the array to help you understand. Notice that [1] doesn't have a [lang] index but [2] does have: [1] =&gt; Array ( [title] =&gt; The Lord of the Rings: The Motion Picture [year] =&gt; [country] =&gt; USA [comment] =&gt; promotional title ) [2] =&gt; Array ( [title] =&gt; Señor de los anillos: La comunidad del anillo, El [year] =&gt; [country] =&gt; Argentina [comment] =&gt; Chile, Mexico, Peru, Spain [lang] =&gt; es ) Thanks!

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• Rails routing of a controller's functions query

  - by Jty.tan

  So I've got a Users controller, and it has (amongst others) a function called details. The idea is that a user can go to localhost:3000/user/:user_id/details and be able to view the details of :user_id. For example, I have a user called "tester". When I go to the uri: http://localhost:3000/users/tester/details I'd want the details function to be called up, to render the details view, and to display the information for the user tester. But instead I get an error saying that No action responded to tester. Actions: change_password, create, current_user, details, forgot_password, index, login_required, new, redirect_to_stored, show, and update_attributes And I understand that to basically mean that if I wanted to access details, I should really be using http://localhost:3000/users/details Except that that isn't really working either... .< That is instead bringing me to http://localhost:3000/users/details/registries (which is the default path that I'd stipulated for anybody trying to view users/:user_id, so again, that's working the way I wanted it to) Point is: Can anybody help and tell me how I can go about getting users/:user_id/details to work the way I want it to and display the details of :user_id? Thanks!

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• Importing ascii file into DataGrid in C# WPF

  - by heckler

  Hi, I just started programming in C# and using WPF so pardon my ignorance. I'm creating an WPF application where I need to dynamically make a grid. The grid headers will be different every time based on information in the text file and I will only need this grid if the user opens it. So right now, I'm able to brows for a file and get the path. Then after I create a datagrid, like this: //Create a new data grid DataGrid datagrid1 = new DataGrid(); Master.Children.Add(datagrid1); Grid.SetRow(datagrid1, 1); Grid.SetColumn(datagrid1, 1); Now, I have issues accessing the file and populating the grid. How would I be able to do this in C#? The file will first have this header: Time x y speed_x speed_y acc_x acc_y Target Leg Type The header can have more paramaters depending on the file. then it will have an unknown amount of row of data like this: 0.00 47.50 -42.50 -1.00 0.00 0.00 0.00 1 1 Sensor_1

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• webBrower Button Click without element ID?

  - by Jeremy

  I'm working on a login system for a forum and trying to make it work via a c# .net form. I need to programitically click the login button on the forum with a webBrower control. So far I have this. webPage page = new webPage(); page.URL = txtURL.Text; page.Load(); //Load the text from the specified URL WebBrowser browser = new WebBrowser(); browser.Document.GetElementById("navbar_username").SetAttribute("value", textBox1.Text); browser.Document.GetElementById("navbar_password").SetAttribute("value", textBox2.Text); HtmlElement el = browser.Document.All["btnI"]; if (el != null) { el.InvokeMember("click"); } else { MessageBox.Show("There is an issue with the program"); } The issue is that the login button on the page does not have an ID or any real information that can allow me to click on it. Does anyone have any suggestions? Here is the code for the login button. <input type="image" src="images/loginbutton.png" class="loginbutton" tabindex="104" value="Log in" title="Enter your username and password in the boxes provided to login, or click the 'register' button to create a profile for yourself." accesskey="s">

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• Complex SQL design, help/advice needed

  - by eugeneK

  Hi, i have few questions for SQL gurus in here ... Briefly this is ads management system where user can define campaigns for different countries, categories, languages. I have few questions in mind so help me with what you can. Generally i'm using ASP.NET and i want to cache all result set of certain user once he asks for statistics for the first time, this way i will avoid large round-trips to server. any help is welcomed Click here for diagram with all details you need for my questions 1.Main issue of this application is to show to the user how many clicks/impressions were and how much money he spent on campaign. What is the easiest way to get this information for him? I will also include filtering by date, date ranges and few other params in this statistics table. 2.Other issue is what happens when user will try to edit campaign. Old campaign will die this means if user set 0.01$ as campaignPPU (pay-per-unit) and next day updates it to 0.05$ all will be reset to 0.05$. 3.If you could re-design some parts of table design so it would be more flexible and easier to modify, how would you do it? Thanks... sorry for so large job but it may interest some SQL guys in here

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• Business Tier | client state in desktop application- way around Stateful Session Beans?

  - by arthur

  I read positive inputs on the following posts concerning client state management: Stateful EJBs in web application?, here, and here. I want to know how implement such client state management for desktop applications (Swing, AWT, SWT, and other). let's assume there are n desktop clients supposed to use some (remote) services provided on an Application Server. How to maintain a separate and permanent data state for each client , distinct from the other without have to use using stateful session Beans (SFSB) ? is that even possible on this application type ? With Webapp(Servlets / JsSF and JSP) some can avoid using SFSB by HttpSession object and/or coupling it with stateless session beans (SLSB). HttpSession object would keep information for each (Web)client separate and the SLSB would play the business logic music. But HttpSession objects aren't present on desktop application and I go stuck with only SFSB and SLSB. Knowing the problems(Concurrency, Error Handling, usw ) of SFSB, I would have not wanted to use it. What would be the other options? is there only SFSB available? Thanks in advances

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• JavaScript change to DropDownList.SelectedIndex not submitted

  - by Bellfalasch

  Hi So, I have a form to submit fighters. You write his/her name, country, and then the team they fight for + the team's country. When you start typing the name I have constructed my own Ajax AutoCompleter. It will find existing fighters that might match. When you click on one of the suggestions it will populate up to four fields depending on existing data in the database. If you're lucky the fighter already exists with information on country, team, and the team's country. The problems starts when submitting. The JavaScript follows and just get's the id of the country to select (also the value of the select-option), and the select-element itself. function dropdownSelect(value, element) { var dropdown = document.getElementById(element); for (var i = 0; i < dropdown.options.length; i++) { if (dropdown.options[i].value == value) { dropdown.options[i].selected = true; return true; } } } When submitting the ASP.NET-code halt's and says that my country-field is null. So my JavaScript-change of selected field couldn't be read by ASP.NET. Is this a limitation of how ASP.NET works? Or a limitation of my skills? ;P

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• Controller actions appear to be synchronous though on different requests?

  - by Oded

  I am under the impression that the below code should work asynchronously. However, when I am looking at firebug, I see the requests fired asynchronously, but the results coming back synchronously: Controller: [HandleError] public class HomeController : Controller { public ActionResult Status() { return Content(Session["status"].ToString()); } public ActionResult CreateSite() { Session["status"] += "Starting new site creation"; Thread.Sleep(20000); // Simulate long running task Session["status"] += "<br />New site creation complete"; return Content(string.Empty); } } Javascript/jQuery: $(document).ready(function () { $.ajax({ url: '/home/CreateSite', async: true, success: function () { mynamespace.done = true; } }); setTimeout(mynamespace.getStatus, 2000); }); var mynamespace = { counter: 0, done: false, getStatus: function () { $('#console').append('.'); if (mynamespace.counter == 4) { mynamespace.counter = 0; $.ajax({ url: '/home/Status', success: function (data) { $('#console').html(data); } }); } if (!mynamespace.done) { mynamespace.counter++; setTimeout(mynamespace.getStatus, 500); } } } Addtional information: IIS 7.0 Windows 2008 R2 Server Running in a VMWare virutual machine Can anyone explain this? Shouldn't the Status action be returning practically immediately instead of waiting for CreateSite to finish? Edit: How can I get the long running process to kick off and still get status updates?

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• Server side aggregation using Spring MVC Controllers

  - by Venu

  Hi! We have a web site with multiple pages each with lot of AJAX calls. All the Ajax calls go to a data proxy layer written in Spring 3 MVC application. In order to reduce the load on the server we are planning to aggregate calls on the client and send to the proxy layer. For ex: we have two calls /controller1/action1 and /controller2/action2 in different controllers. I want to write an aggregate controller and call it from the client instead of making two calls to the individual controllers. Something like /aggregatecontroller/aggregate (and we will post the information regarding which calls are being aggregated and required parameters). Is there any way we can call another controller/action from a controller/action and get output? The flow will be something like this: a. Call /aggregatecontroller/aggregate with info regd call1 and call2 b. aggregate action understands that it needs to aggregate call1 and call2 c. it calls /controller1/action1 and gets the response d. it calls /controller2/action2 and gets the response e. it merges both in a json response and sends it back to browser. Please let me know if you have any suggestion regd how to do this or if you think there is a better approach to do the server side aggregation. Thanks for your time.

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• Is there an efficient way in LINQ to use a contains match if and only if there is no exact match?

  - by Peter

  I have an application where I am taking a large number of 'product names' input by a user and retrieving some information about each product. The problem is, the user may input a partial name or even a wrong name, so I want to return the closest matches for further selection. Essentially if product name A exactly matches a record, return that, otherwise return any contains matches. Otherwise return null. I have done this with three separate statements, and I was wondering if there was a more efficient way to do this. I am using LINQ to EF, but I materialize the products to a list first for performance reasons. productNames is a List of product names (input by the user). products is a List of product 'records' var directMatches = (from s in productNames join p in products on s.ToLower() equals p.name.ToLower() into result from r in result.DefaultIfEmpty() select new {Key = s, Product = r}); var containsMatches = (from d in directMatches from p in products where d.Product == null && p.name.ToLower().Contains(d.Key) select new { d.Key, Product = p }); var matches = from d in directMatches join c in containsMatches on d.Key equals c.Key into result from r in result.DefaultIfEmpty() select new {d.Key, Product = d.Product ?? (r != null ? r.Product: null) };

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• Getting visitors country from their IP

  - by Ali Abdulkarim Salem

  i want to get visitors country via their IP.. right now I'm using this ( http://api.hostip.info/country.php?ip=...... ) here's my code <?php if (isset($_SERVER['HTTP_CLIENT_IP'])) { $real_ip_adress = $_SERVER['HTTP_CLIENT_IP']; } if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) { $real_ip_adress = $_SERVER['HTTP_X_FORWARDED_FOR']; } else { $real_ip_adress = $_SERVER['REMOTE_ADDR']; } $cip = $real_ip_adress; $iptolocation = 'http://api.hostip.info/country.php?ip=' . $cip; $creatorlocation = file_get_contents($iptolocation); ?> Well, it's working properly, but the thing is, this returns the country code like US or CA., and not the whole country name like United States or Canada So, is there any good alternative to hostip.info offers this? I know that I can just write some code that will eventually turn this two letters to whole country name, but I'm just too lazy to write a code that contains all countries... P.S: For some reason I don't want to use any ready made CSV file or any code that will grab this information for me, something like ip2country ready made code and CSV.

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• Making a Function-Activated Link Appear Without Having to Refresh Browser

  - by John

  Hello, I'm trying to use the code below to make the <a href='http://www...com/.../footervote.php'>Vote</a> link appear if a user logs in and a user shows up in the function getEditorsList(). The vote link only appears if the browser is refreshed. Any idea how I could make the vote link appear without having to refresh the browser? Thanks in advance, John index.php: <?php require_once "header.php"; //content include "login.php"; // more content require_once "footer.php"; ?> In header.php: <?php error_reporting(0); session_start(); require_once ('db_connect.inc.php'); require_once ("function.inc.php"); $seed="0dAfghRqSTgx"; $domain = "...com"; $editors = getEditorsList(); foreach($editors as $editor) { $editorids[] = $editor['loginid']; } if(in_array($_SESSION['loginid'], $editorids)) { echo "<div class='footervote'><a href='http://www...com/.../footervote.php'>Vote</a></div>"; } ?> login.php: <?php if (!isLoggedIn()) { if (isset($_POST['cmdlogin'])) { if (checkLogin($_POST['username'], $_POST['password'])) { show_userbox(); } else { echo "Incorrect Login information !"; show_loginform(); } } else { show_loginform(); } } else { show_userbox(); } ?>

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• Can an ASP.NET user control determine its context or its parent .aspx file

  - by John Galt

  Is it possible for a user control to determine its "context" or its parent .aspx page in some way? Right now I have a user control that is declared on a typical .aspx page as follows: <%@ Register TagPrefix="uc1" TagName="ManageTitle" Src="../UserControls/ManageTitle.ascx" %> The user control currently emits a textbox as follows: <asp:textbox id="txtTitle" runat="server" MaxLength="60" ToolTip="Describe the item with a short pithy title - most important keywords first"/> The page_load for this .ascx file is currently like this: Me.txtTitle.Text = SetPageTitle() While some places in this web app need this (i.e. a textbox where end-user can type a "title"), I have other places where I want to show the "title" information in a "read-only" way. For example, rather than a textbox, I could use a label control or a textbox with Enabled="false" to prevent data entry. I suppose I could clone this small .ascx file and append a suffix to its name like _RO.ascx or something but I am wondering what the best approach would be. In short, can a user control get some sort of "context" from the page that declares it or is there an altogether better way to accomplish this sort of thing? Thank you.

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• Any suggestions to improve my PDO connection class?

  - by Scarface

  Hey guys I am pretty new to pdo so I basically just put together a simple connection class using information out of the introductory book I was reading but is this connection efficient? If anyone has any informative suggestions, I would really appreciate it. class PDOConnectionFactory{ public $con = null; // swich database? public $dbType = "mysql"; // connection parameters public $host = "localhost"; public $user = "user"; public $senha = "password"; public $db = "database"; public $persistent = false; // new PDOConnectionFactory( true ) <--- persistent connection // new PDOConnectionFactory() <--- no persistent connection public function PDOConnectionFactory( $persistent=false ){ // it verifies the persistence of the connection if( $persistent != false){ $this->persistent = true; } } public function getConnection(){ try{ $this->con = new PDO($this->dbType.":host=".$this->host.";dbname=".$this->db, $this->user, $this->senha, array( PDO::ATTR_PERSISTENT => $this->persistent ) ); // carried through successfully, it returns connected return $this->con; // in case that an error occurs, it returns the error; }catch ( PDOException $ex ){ echo "We are currently experiencing technical difficulties. We have a bunch of monkies working really hard to fix the problem. Check back soon: ".$ex->getMessage(); } } // close connection public function Close(){ if( $this->con != null ) $this->con = null; } }

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• Can't understand sessions in Rails

  - by ciss

  Hello everyone. Please don't bit my for my misunderstanding. The sessions are very new for me, and i have some problems. Okay i read many information about sessions and especially rails session. But this don't give me right imagine about sessions. Did i understand right, when users send request to server (get) - Server create a new session (and store this some file in hard drive with session id), session id - is a random generated num? so, server create a new session (and store session on drive) after this server send back answer to client and set session_id in cookies? Ok, i debug some params and see some results: debug(session): {:_csrf_token=>"jeONIfNxFmnpDn/xt6I0icNK1m3EB3CzT9KMntNk7KU=", :session_id=>"06c5628155efaa6446582c491499af6d", "flash"=>{}} debug(cookies): {"remember_user_token"=>"1::3GFRFyXb83lffzwPDPQd", "_blog_session"=>"BAh7CDoQX2NzcmZfdG9rZW4iMWplT05JZk54Rm1ucERuL3h0NkkwaWNOSzFtM0VCM0N6VDlLTW50Tms3S1U9Og9zZXNzaW9uX2lkIiUwNmM1NjI4MTU1ZWZhYTY0NDY1ODJjNDkxNDk5YWY2ZCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA==--348c88b594e98f4bf6389d94383134fbe9b03095"} Okay, i know, what _csrf_token helps to prevent csrf. session_id - is id of the session which stored on hard drive (by default) but what is _blog_session in cookies? also, remeber_user_token containes my id (1::*) and what about second part, what is it? Sorry for this stupid questions, i know what i can easy use any nice auth-plugins (authlogic/clearance/devise), but i want to fully understand sessions. Thank you. (also sorry for my english, this is not my native language)

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• Greasemonkey failing to GM_setValue()

  - by HonoredMule

  I have a Greasemonkey script that uses a Javascript object to maintain some stored objects. It covers quite a large volume of information, but substantially less than it successfully stored and retrieved prior to encountering my problem. One value refuses to save, and I can not for the life of me determine why. The following problem code: Works for other larger objects being maintained. Is presently handling a smaller total amount of data than previously worked. Is not colliding with any function or other object definitions. Can (optionally) successfully save the problem storage key as "{}" during code startup. this.save = function(table) { var tables = this.tables; if(table) tables = [table]; for(i in tables) { logger.log(this[tables[i]]); logger.log(JSON.stringify(this[tables[i]])); GM_setValue(tables[i] + "_" + this.user, JSON.stringify(this[tables[i]])); logger.log(tables[i] + "_" + this.user + " updated"); logger.log(GM_getValue(tables[i] + "_" + this.user)); } } The problem is consistently reproducible and the logging statments produce the following output in Firebug: Object { 54,10 = Object } // Expansion shows complete contents as expected, but there is one oddity--Firebug highlights the array keys in purple instead of the usual black for anonymous objects. {"54,10":{"x":54,"y":10,"name":"Lucky Pheasant"}} // The correctly parsed string. bookmarks_HonoredMule saved undefined I have tried altering the format of the object keys, to no effect. Further narrowing down the issue is that this particular value is successfully saved as an empty object ("{}") during code initialization, but skipping that also does not help. Reloading the page confirms that saving of the nonempty object truly failed. Any idea what could cause this behavior? I've thoroughly explored the possibility of hitting size constraints, but it doesn't appear that can be the problem--as previously mentioned, I've already reduced storage usage. Other larger objects save still, and the total number of objects, which was not high already, has further been reduced by an amount greater than the quantity of data I'm attempting to store here.

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• MySql "comments" parameter as descriptor?

  - by Nick

  So, I'm trying to learn a lot at once, and this place is really helpful! I'm making a little running log website for myself and maybe a few other people, and I have it so that the user can add workouts for each day. With each workout, I have a variety of information the user can fill out for the workout, such as running distance, time, quality of run, course, etc... I store this in a MySql database as a table with fields titled "distance", "time", "runquality", etc... Now, these field titles don't match up with what I want displayed on the running log, so I was thinking of using the "Comments" attribute for a field to store its human-readable title--thus the field "runquality" would have "Quality of run" as its comment, and then I would pull the comment with a SQL query and display it instead of the field name. Is this a good theoretical/practical way of going about it? And what sort of SQL would I use to pull the comment for the field anyway? Secondly, suppose I want to add the ability for the user to create their own workout descriptors. So say a user wants to add a "temperature" descriptor for their workout. Should I create a script that adds fields to my workout table, or should I create a separate table listing only workout descriptors and somehow link the descriptor table with the "contents" table? I haven't learned any theory about database design or anything so any help is appreciated!

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• How to extend a jquery ui widget ? (1.7)

  - by Jide

  I would like to create a custom version of the sortable widget. I have been searching for documentation, but could not find something really accurate. The best information I found was : http://jqueryui.pbworks.com/Widget-factory. I tried : $.widget("ui.customsortable", $.extend($.ui.sortable, { _init: function() { $.widget.prototype._init.apply(this, arguments); } })); But $.widget.prototype._init is not the function I want to call I guess since it is the $.widget prototype. Then, I tried something I read here and there : var _init = $.ui.sortable.prototype._init; $.widget("ui.customsortable", $.extend($.ui.sortable, { _init: function() { _init.apply(this, arguments); }, })); But : I can't believe I have to store all methods I want to override like this, it is so ugly. It throws an error ("this.refresh is not a function"), which means the refresh method does not exist. Does that mean I would have to recreate all methods I want to override ? What's the point of extending in that case ? Am I missing something here ? Thanks for your help !

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• How much is too much memory allocation in NDK?

  - by Maximus

  The NDK download page notes that, "Typical good candidates for the NDK are self-contained, CPU-intensive operations that don't allocate much memory, such as signal processing, physics simulation, and so on." I came from a C background and was excited to try to use the NDK to operate most of my OpenGL ES functions and any native functions related to physics, animation of vertices, etc... I'm finding that I'm relying quite a bit on Native code and wondering if I may be making some mistakes. I've had no trouble with testing at this point, but I'm curious if I may run into problems in the future. For example, I have game struct defined (somewhat like is seen in the San-Angeles example). I'm loading vertex information for objects dynamically (just what is needed for an active game area) so there's quite a bit of memory allocation happening for vertices, normals, texture coordinates, indices and texture graphic data... just to name the essentials. I'm quite careful about freeing what is allocated between game areas. Would I be safer setting some caps on array sizes or should I charge bravely forward as I'm going now?

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• lapply slower than for-loop when used for a BiomaRt query. Is that expected?

  - by ptocquin

  I would like to query a database using BiomaRt package. I have loci and want to retrieve some related information, let say description. I first try to use lapply but was surprise by the time needed for the task to be performed. I thus tried a more basic for-loop and get a faster result. Is that expected or is something wrong with my code or with my understanding of apply ? I read other posts dealing with *apply vs for-loop performance (Here, for example) and I was aware that improved performance should not be expected but I don't understand why performance here is actually lower. Here is a reproducible example. 1) Loading the library and selecting the database : library("biomaRt") athaliana <- useMart("plants_mart_14") athaliana <- useDataset("athaliana_eg_gene",mart=athaliana) 2) Querying the database : loci <- c("at1g01300", "at1g01800", "at1g01900", "at1g02335", "at1g02790", "at1g03220", "at1g03230", "at1g04040", "at1g04110", "at1g05240" ) I create a function for the use in lapply : foo <- function(loci) { getBM("description","tair_locus",loci,athaliana) } When I use this function on the first element : > system.time(foo(cwp_loci[1])) utilisateur système écoulé 0.020 0.004 1.599 When I use lapply to retrieve the data for all values : > system.time(lapply(loci, foo)) utilisateur système écoulé 0.220 0.000 16.376 I then created a new function, adding a for-loop : foo2 <- function(loci) { for (i in loci) { getBM("description","tair_locus",loci[i],athaliana) } } Here is the result : > system.time(foo2(loci)) utilisateur système écoulé 0.204 0.004 10.919 Of course, this will be applied to a big list of loci, so the best performing option is needed. I thank you for assistance. EDIT Following recommendation of @MartinMorgan Simply passing the vector loci to getBM greatly improves the query efficiency. Simpler is better. > system.time(lapply(loci, foo)) utilisateur système écoulé 0.236 0.024 110.512 > system.time(foo2(loci)) utilisateur système écoulé 0.208 0.040 116.099 > system.time(foo(loci)) utilisateur système écoulé 0.028 0.000 6.193

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• What would be a better implementation of shared variable among subclass

  - by Churk

  So currently I have a spring unit testing application. And it requires me to get a session cookie from a foreign authentication source. Problem what that is, this authentication process is fairly expensive and time consuming, and I am trying to create a structure where I am authenticate once, by any subclass, and any subsequent subclass is created, it will reuse this session cookie without hitting the authentication process again. My problem right now is, the static cookie is null each time another subclass is created. And I been reading that using static as a global variable is a bad idea, but I couldn't think of another way to do this because of Spring framework setting things during run time and how I would set the cookie so that all other classes can use it. Another piece of information. The variable is being use, but is change able during run time. It is not a single user being signed in and used across the board. But more like a Sub1 would call login, and we have a cookie. Then multiple test will be using that login until SubX will come in and say, I am using different credential, so I need to login as something else. And repeats. Here is a outline of my code: public class Parent implements InitializingBean { protected static String BASE_URL; public static Cookie cookie; ... All default InitializingBean methods ... afterPropertiesSet() { cookie = // login process returns a cookie } } public class Sub1 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomething() { // Do something with cookie, because it should have been set by parent class } } public class Sub2 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomethingElse() { // Do something with cookie, because it should have been set by parent class } }

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• Can somebody explain this remark in the MSDN CreateMutex() documentation about the bInitialOwner fla

  - by Tom Williams

  The MSDN CreatMutex() documentation (http://msdn.microsoft.com/en-us/library/ms682411%28VS.85%29.aspx) contains the following remark near the end: Two or more processes can call CreateMutex to create the same named mutex. The first process actually creates the mutex, and subsequent processes with sufficient access rights simply open a handle to the existing mutex. This enables multiple processes to get handles of the same mutex, while relieving the user of the responsibility of ensuring that the creating process is started first. When using this technique, you should set the bInitialOwner flag to FALSE; otherwise, it can be difficult to be certain which process has initial ownership. Can somebody explain the problem with using bInitialOwner = TRUE? Earlier in the same documentation it suggests a call to GetLastError() will allow you to determine whether a call to CreateMutext() created the mutex or just returned a new handle to an existing mutex: Return Value If the function succeeds, the return value is a handle to the newly created mutex object. If the function fails, the return value is NULL. To get extended error information, call GetLastError. If the mutex is a named mutex and the object existed before this function call, the return value is a handle to the existing object, GetLastError returns ERROR_ALREADY_EXISTS, bInitialOwner is ignored, and the calling thread is not granted ownership. However, if the caller has limited access rights, the function will fail with ERROR_ACCESS_DENIED and the caller should use the OpenMutex function.

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