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• I just discovered why all ASP.Net websites are slow, and I am trying to work out what to do about it

  - by James

  I just discovered that every request in an ASP.Net web application gets a Session lock at the begging of a request, and then releases it at the end of the request!!! I mean, WTF Microsoft! In case the implication is lost on you, as it was from me at first, this basically means the following: Anytime an ASP.Net webpage is taking a long time to load (maybe due to a slow database call or whatever), and the user decides they want to navigate to a different page because they are tired of waiting, THEY CANT! The ASP.Net session lock forces the new page request to wait until the original request has finished its painfully slow load. Arrrgh. Anytime an UpdatePanel is loading slowly, and the user decides to navigate to a different page before the UpdadePanel has finished updating... THEY CANT! The ASP.Net session lock forces the new page request to wait until the original request has finished its painfully slow load. Double Arrrgh! So what are the options? So far I have come up with: Implement a Custom SessionStateDataStore, which ASP.Net supports. I haven't found too many out there to copy, and it seems kind of high risk and easy to mess up. Keep track of all requests in progress, and if a request comes in from the same user, cancel the original request. Seems kind of extreme, but it would work (I think) Don't user Session! When I need some kind of state for the user, I could just user Cache instead, and key items on the authenticated user's name, or some such thing. Again seems kind of extreme I really can't believe that the ASP.Net Microsoft team would have left such a huge performance bottleneck in the framework at version 4.0! Am I missing something obvious? How hard would it be to use a ThreadSafe collection for the Session? Arrrrghhhhhh. Any advice much appreciated.

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• Deterministic floating point and .NET

  - by code2code

  How can I guarantee that floating point calculations in a .NET application (say in C#) always produce the same bit-exact result? Especially when using different versions of .NET and running on different platforms (x86 vs x86_64). Inaccuracies of floating point operations do not matter. In Java I'd use strictfp. In C/C++ and other low level languages this problem is essentially solved by accessing the FPU / SSE control registers but that's probably not possible in .NET. Even with control of the FPU control register the JIT of .NET will generate different code on different platforms. Something like HotSpot would be even worse in this case... Why do I need it? I'm thinking about writing a real-time strategy (RTS) game which heavily depends on fast floating point math together with a lock stepped simulation. Essentially I will only transmit user input across the network. This also applies to other games which implement replays by storing the user input. Not an option are: decimals (too slow) fixed point values (too slow and cumbersome when using sqrt, sin, cos, tan, atan...) update state across the network like an FPS: Sending position information for hundreds or a few thousand units is not an option Any ideas?

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• Asynchronous SQL Operations

  - by Paul Hatcherian

  I've got a problem I'm not sure how best to solve. I have an application which updates a database in response to ad hoc requests. One request in particular is quite common. The request is an update that by itself is quite simple, but has some complex preconditions. For this request the business layer first requests a set of data from the data layer. The business logic layer evaluated the data from the database and parameters from the request, from this the action to be performed is determined, and the request's response message(s) are created. The business layer now executes the actual update command that is the purpose of the request. This last step is the problem, this command is dependent on the state of the database, which might have changed since the business logic ran. Locking down the data read in this operation across several round-trips to the database doesn't seem like a good idea either. Is there a 'best-practice' way to accomplish something like this? Thanks!

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• How to pass javascript/jQuery settings from page to page in rails?

  - by aronchick

  When doing javascript manipulation of what's visible, how does one pass that from page to page (ideally in Rails)? For example, let's say I have the following simple jQuery code: <% link_to "Next Page", report_path %> <div class="clickable-div" style="background-color:#FFFFFF;"></div> <script> $('.clickable-div').click(function () { var color = $(this).css("background-color", "#000000"); }); </script> If it's not clear, the code is just supposed to change the color of the div based on whether or not it has been clicked. Regardless, there's also a link on the page that allows someone to go to the reporting page. What's a way to pass the state of the div to the action call? EDIT It seems unnecessary to do it in a session - am I wrong? This is just something from one page to the next, I couldn't care less anywhere else on the site. EDIT 2 To confirm, Rails needs to have access to the action that occurred in Javascript on the previous page.

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• How to handle 30k files in a project which requires them?

  - by Jeremiah

  Visual Studio 2010 RC - Silverlight Application We have a library of images that we need to have access to. They are given to us from a vendor (through an installer) and they are not in a database, they are files in a folder (a very large monster of a folder). We do not control when the images change, so the vendor needs to be able to override them individually. We get updates frequently enough from this vendor to state that these images change "randomly" and without our (programmer) knowledge. The problem: I don't want 30K images in SVN. Heck, I don't even want to imagine them in my Solution. However, our application requires them in order to run properly. So, our build/staging servers need access to these images (we have two build servers). The Question: How would you handle it when your application will not work as specified without access to each of 30k images and you don't control when those images change? I'm do not want to have a crazy large SVN repository. Because I don't know when any of these images change, I really don't want them in my solution (definitely do not want a large solution, either). I also don't want a bunch of manual steps to do every time these images change. Our mantra, up to this point, has always been, any developer could download from SVN, compile and run our app. These images are going to kill that mantra. I'm tempted to make a WCF service that will return images if they exist and a dummy image if they don't. This way all dev boxes will return a dummy image and our build/staging/production boxes will return real images (ones that actually have the vendor's image installer installed on). This has to be a solved problem. What have other people done to handle these types of problems? I'm open to suggestions.

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• R Tree 50,000 foot overview?

  - by roufamatic

  I'm working on a school project that involves taking a lat/long point and finding the top five closest points in a known list of places. The list is to be stored in memory, with the caveat that we must choose an "appropriate data structure" -- that is, we cannot simply store all the places in an array and compare distances one-by-one in a linear fashion. The teacher suggested grouping the place data by US State to prevent calculating the distance for places that are obviously too far away. I think I can do better. From my research online it seems like an R-Tree or one of its variants might be a neat solution. Unfortunately, that sentence is as far as I've gotten with understanding the actual technique, as the literature is simply too dense for my non-academic head. Can somebody give me a really high overview of what the process is for populating an R-Tree with lat/long data, and then traversing the tree to find those 5 nearest neighbors of a given point? Additionally the project is in C, and I don't have to reinvent the wheel on this, so if you've used an existing open source C implementation of an R Tree I'd be interested in your experiences.

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• Will WCF allow me to use object references across boundries on objects that implement INotifyPropert

  - by zimmer62

  So I've created a series of objects that interact with a piece of hardware over a serial port. There is a thread running monitoring the serial port, and if the state of the hardware changes it updates properties in my objects. I'm using observable collections, and INotifyPropertyChanged. I've built a UI in WPF and it works great, showing me real time updating when the hardware changes and allows me to send changes to the hardware as well by changing these properties using bindings. What I'm hoping is that I can run the UI on a different machine than what the hardware is hooked up to without a lot of wiring up of events. Possibly even allow multiple UI's to connect to the same service and interact with this hardware. So far I understand I'm going to need to create a WCF service. I'm trying to figure out if I'll be able to pass a reference to an object created at the service to the client leaving events intact. So that the UI will really just be bound to a remote object. Am I moving the right direction with WCF? Also I see tons of examples for WCF in C#, are there any good practical use examples in VB that might be along the lines of what I'm trying to do?

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• Is it possible to load an entire SQL Server CE database into RAM?

  - by DanM

  I'm using LinqToSql to query a small SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table via a foreign key, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of the appeal of LinqToSql. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view.

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• Suitable data structures for saving files in localStorage (HTML5) ?

  - by WmasterJ

  It is nice when there isn't a DB to maintain and users to authenticate. My professor has asked me to convert a recent research project of his that uses Bespin and calculates errors made by users in a code editor as part of his research. The goal is to convert from MySQL to using HTML5 localStorage completely. Doesn't seem so hard to do, even though digging in his code might take some time. Question: I need to store files and state (last placement of cursor and active file). I have already done so by implementing the recommendations in another stackoverflow thread. But would like your input considering how to structure the content to use. My current solution Hashmap like solution with javascript objects: files = {}; // later, saving files[fileName] = data; And then storing in localStorage using some recommendations localStorage.setObject("files", files); // Note that setObject(key, data) does not exist but is added // using Storage.prototype.setObject = function() {... Currently I'm also considering using some type of numeric id. So that names can be changed without any hassle renaming the key in the hashmap. What is your opinion on the way it is solved and would you do it any differently?

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• How to convert a lambda to an std::function using templates

  - by retep998

  Basically, what I want to be able to do is take a lambda with any number of any type of parameters and convert it to an std::function. I've tried the following and neither method works. std::function([](){});//Complains that std::function is missing template parameters template <typename T> void foo(function<T> f){} foo([](){});//Complains that it cannot find a matching candidate The following code does work however, but it is not what I want because it requires explicitly stating the template parameters which does not work for generic code. std::function<void()>([](){}); I've been mucking around with functions and templates all evening and I just can't figure this out, so any help would be much appreciated. As mentioned in a comment, the reason I'm trying to do this is because I'm trying to implement currying in C++ using variadic templates. Unfortunately, this fails horribly when using lambdas. For example, I can pass a standard function using a function pointer. template <typename R, typename...A> void foo(R (*f)(A...)) {} void bar() {} int main() { foo(bar); } However, I can't figure out how to pass a lambda to such a variadic function. Why I'm interested in converting a generic lambda into an std::function is because I can do the following, but it ends up requiring that I explicitly state the template parameters to std::function which is what I am trying to avoid. template <typename R, typename...A> void foo(std::function<R(A...)>) {} int main() { foo(std::function<void()>([](){})); }

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• Recursion - Ship Battle

  - by rgorrosini

  I'm trying to write a little ship battle game in java. It is 100% academic, I made it to practice recursion, so... I want to use it instead of iteration, even if it's simpler and more efficient in most some cases. Let's get down to business. These are the rules: Ships are 1, 2 or 3 cells wide and are placed horizontally only. Water is represented with 0, non-hit ship cells are 1, hit ship cells are 2 and sunken ships have all it's cells in 3. With those rules set, I'm using the following array for testing: int[][] board = new int[][] { {0, 1, 2, 0, 1, 0}, {0, 0, 1, 1, 1, 0}, {0, 3, 0, 0, 0, 0}, {0, 0, 2, 1, 2, 0}, {0, 0, 0, 1, 1, 1}, }; It works pretty good so far, and to make it more user-friendly I would like to add a couple of reports. these are the methods I need for them: Given the matrix, return the amount of ships in it. Same as a), but separating them by state (amount of non-hit ships, hit and sunken ones). I will need a hand with those reports, and I would like to get some ideas. Remember it must be done using recursion, I want to understand this, and the only way to go is practice! Thanks a lot for your time and patience :).

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• How to get notified about changes of the history via history.pushState?

  - by Felix Kling

  So now that HTML5 introduces history.pushState to change the browsers history, websites start using this in combination with Ajax instead of changing the fragment identifier of the URL. Sadly that means that those calls cannot be detect anymore by onhashchange. My question is: Is there a reliable way (hack? ;)) to detect when a website uses history.pushState? The specification does not state anything about events that are raised (at least I couldn't find anything). I tried to create a facade and replaced window.history with my own JavaScript object, but it didn't have any effect at all. Further explanation: I'm developing a Firefox add-on that needs to detect these changes and act accordingly. I know there was a similar question a few days ago that asked whether listening to some DOM events would be efficient but I would rather not rely on that because these events can be generated for a lot of different reasons. Update: Here is a jsfiddle (use Firefox 4 or Chrome 8) that shows that onpopstate is not triggered when pushState is called (or am I doing something wrong? Feel free to improve it!). Update 2: Another (side) problem is that window.location is not updated when using pushState (but I read about this already here on SO I think).

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• Django Getting RequestContext in custom tag

  - by greggory.hz

  I'm trying to create a custom tag. Inside this custom tag, I want to be able to have some logic that checks if the user is logged in, and then have the tag rendered accordingly. This is what I have: class UserActionNode(template.Node): def __init__(self): pass def render(self, context): if context.user.is_authenticated(): return render_to_string('layout_elements/sign_in_register.html'); else: return render_to_string('layout_elements/logout_settings.html'); def user_actions(parser, test): return UserActionNode() register.tag('user_actions', user_actions) When I run this, I get this error: Caught AttributeError while rendering: 'Context' object has no attribute 'user' The view that renders this looks like this: return render_to_response('start/home.html', {}, context_instance=RequestContext(request)) Why doesn't the tag get a RequestContext object instead of the Context object? How can I get the tag to receive the RequestContext instead of the Context? EDIT: Whether or not it's possible to get a RequestContext inside a custom tag, I'd still be interested to know the "correct" or best way to determine a user's authentication state from within the custom tag. If that's not possible, then perhaps that kind of logic belongs elsewhere? Where?

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• Adding cancel ability and exception handling to async code.

  - by Rob

  I have this sample code for async operations (copied from the interwebs) public class LongRunningTask { public LongRunningTask() { //do nowt } public int FetchInt() { Thread.Sleep(2000); return 5; } } public delegate TOutput SomeMethod<TOutput>(); public class GoodPerformance { public void BeginFetchInt() { LongRunningTask lr = new LongRunningTask(); SomeMethod<int> method = new SomeMethod<int>(lr.FetchInt); // method is state object used to transfer result //of long running operation method.BeginInvoke(EndFetchInt, method); } public void EndFetchInt(IAsyncResult result) { SomeMethod<int> method = result.AsyncState as SomeMethod<int>; Value = method.EndInvoke(result); } public int Value { get; set; } } Other async approaches I tried required the aysnc page attribute, they also seemed to cancel if other page elements where actioned on (a button clicked), this approach just seemed to work. I’d like to add a cancel ability and exception handling for the longRunningTask class, but don’t erm, really know how.

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• Is there unresizable space in latex? Pictures in good looking grid.

  - by drasto

  I've created latex macro to typeset guitar chords diagrams(using picture environment). Now I want to make diagrams of different appear in good looking grid when typeset one next to each other as the picture shows: The picture. (on the picture: Labeled "First" bad layout of diagrams, labeled "Second" correct layout when equal number of diagrams in line) I'm using \hspace to make some skips between diagrams, otherwise they would be too near to each other. As you can see in second case when latex arrange pictures in so that there is same number of them in each line it works. However if there is less pictures in the last line they become "shifted" to the right. I don't want this. I guess is because latex makes the space between diagrams in first line a little longer for the line to exactly fit the page width. How do I tell latex not to resize spaces created by \hspace ? Or is there any other way ? I guess I cannot use tables because I don't know how many diagrams will fit in one line... This is current state of code: \newcommand{\spaceForChord}{1.7cm} \newcommnad{\chordChart}[1]{% %calculate dimensions xdim and ydim according to setings \begin{picture}(xdim, ydim){% %draw the diagram inside defined area }% \hspace*{\spaceForChord}% \hspace*{-\xdim}% }% %end preambule and begin document \begin{document} First:\\* \\* \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} \chordChart{...some arguments for to change diagram look...} %...above line is repeated 12 more times to produce result shown at the picture \end{document} Thanks for any help.

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• Returning two or more values from a function

  - by cf_PhillipSenn

  I need to return multiple values from a ColdFusion function in an ajax callback function. Here's what I've got: $('input[name="StateName"]').live('change', function() { var StateID = $(this).parents('tr').attr('id'); var StateName = $(this).val(); $.ajax({ url: 'Remote/State.cfc' ,type: "POST" ,data: { 'method': 'UpdateStateName' ,'StateID': StateID ,'StateName': StateName } ,success: function(result){ if (isNaN(result)) { $('#msg').text(result).addClass('err'); } else { $('#' + result + ' input[name="StateName"]').addClass('changed'); }; } ,error: function(msg){ $('#msg').text('Connection error').addClass('err'); } }); }); If I trap a database error, then the success callback is fired, and the result is Not a Number (It is in fact, the text of the error message). I need the function to also pass back other values. One might be the primary key of the row that caused the error. Another might be the old StateName, so that I can refresh the old value on the screen so that the client will know absolutely for sure that their change did not take effect. I guess I'm breaking the rule of atomicity here and need to fix that, because I'm using result as both the primary key of the row that was updated, or it's the error message if the update fails. I need to return both the primary key and the error message.

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• Rails: creating a model in the new action

  - by Joseph Silvashy

  I have an interesting situation, well it's probably not that unique at all, but I'm not totally sure how to tackle it. I have a model, in this case a recipe and the user navigates to the new path /recipes/new however the situation is that I need to be able to have the user upload images and make associations to that model in the new action, but the model doesn't have an ID yet. So I assume I need to rethink my controller, but I don't want to have redirects and whatnot, how can accomplish this? Here is the basic controller, barebones obviously: ... def new # I should be creating the model first, so it has an ID @recipe = Recipe.new end def create @recipe = Recipe.new(params[:recipe]) if @recipe.save redirect_to @recipe else render 'new' end end ... update Perhaps I can have a column thats like state which could have values like new/incomplete/complete or what-have-you. I'm mostly trying to figure out what would also be most efficient for the DB. It would be nice if I could still have a url that said '/new', instead of it be the edit path with the id, for usability sake, but I'm not sure this can be simply accomplished in the new action of my controller. Thoughts?

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• Cordova polluted logs with persistent.js add()

  - by slaver113

  I am using the latest phonegap/cordova version 2.1. and my log in Eclipse logcat get polluted with code when i do var allItems = Item.all(); allItems.list(null, function (results) { results.forEach(function (r) { console.log(r.id+ " " + r.lat + " " + r.long + " " + r.state); }); }); I get a output like (for 100s of lines) 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } function (value) { 10-29 10:56:13.270: I/Web Console(5961): if (value === undefined) { 10-29 10:56:13.270: I/Web Console(5961): return getterCallback(); 10-29 10:56:13.270: I/Web Console(5961): } else { 10-29 10:56:13.270: I/Web Console(5961): setterCallback(value); 10-29 10:56:13.270: I/Web Console(5961): return scope; 10-29 10:56:13.270: I/Web Console(5961): } 10-29 10:56:13.270: I/Web Console(5961): } at :1149822901

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• Getting a particular menu item from MainMenu

  - by Garry

  I have a nib (winA.xib) that contains a window. My app delegate contains an NSWindowController subclass called WinAController. WinAController has a property (NSMenu *mainMenu) that I want to point to the MainMenu. I have set it after I instantiate WinAController with this code: WinAController = [[WinAController alloc] initWithWindowNibName:@"WinA"]; WinAController.mainMenu = [NSApp mainMenu]; I have a menu item underneath the "Window" top-level menu item on MainMenu that invokes the [WinAController showWindow] method and displays WinA. I want to toggle the on/off state of this menu item depending on whether WinA is visible or not. WinAController also has another property (NSMenuItem *myMenuItem). How can I get a reference to a sub menu of the "Window" top-level menu item. The title of sub menu item I want to get is "Command". I have tried this: if (mainMenu != nil) { myMenuItem = [mainMenu itemAtIndex:[mainMenu indexOfItemWithTitle:@"Command"]]; } But it doesn't seem to work. Where am I going wrong? Thanks,

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• What techniques can I employ to create a series of UI Elements from a collection of objects using WP

  - by elggarc

  I'm new to WPF and before I dive in solving a problem in completely the wrong way I was wondering if WPF is clever enough to handle something for me. Imagine I have a collection containing objects. Each object is of the same known type and has two parameters. Name (a string) and Picked (a boolean). The collection will be populated at run time. I would like to build up a UI element at run time that will represent this collection as a series of checkboxes. I want the Picked parameter of any given object in the collection updated if the user changes the selected state of the checkbox. To me, the answer is simple. I iterate accross the collection and create a new checkbox for each object, dynamically wiring up a ValueChanged event to capture when Picked should be changed. It has occured to me, however, that I may be able to harness some unknown feature of WPF to do this better (or "properly"). For example, could data binding be employed here? I would be very interested in anyone's thoughts. Thanks, E FootNote: The structure of the collection can be changed completely to better fit any chosen solution but ultimately I will always start from, and end with, some list of string and boolean pairs.

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• How to repair Java in Ubuntu after trying to switch to Java 6 using update-java-alternatives

  - by Kau-Boy

  I tried to switch from Java 5 to Java 6 using the "update-java-alternatives" command like explained on this page: https://help.ubuntu.com/community/Java But afterwards I get the following error when I tried to execute java: root@webserver:~# java Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. I also tried to reinstall the java binaries using "apt-get" but I didn't succeed reinstalling it. I would like to post the "apt-get" errors, but unfortunately I don't know how to print out the error messages in English and not in German. My system is a Ubuntu 8.04 ROOT server. Here is the (Google translated) english text tring to install Java 6 again: root@server:~# apt-get install sun-java6-jdk Reading package lists ... Ready Dependency tree Reading state information ... Ready sun-java6-jdk is already the newest version. sun-java6-jdk set to manually installed. 0 upgraded, 0 newly installed, 0 to remove and 86 not upgraded. 1 not fully installed or removed. After this operation, 0B of additional disk space will be used. Set up a sun-java6-bin (6-03-0ubuntu2) ... Could not create the Java virtual machine. dpkg: error processing sun-java6-bin (- configure): Subprocess post-installation script returned error exit status 1 Errors were encountered while processing: sun-java6-bin E: Sub-process / usr / bin / dpkg returned an error code (1) I hope that this might help you helping me.

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• php search database for row

  - by Brenden Morley

  Okay I got code the code to pull data based on a users account number well here is what im using (And yes I know it isnt safe now that is the reason for my post) <?php include('config.php'); $user_info = fetch_user_info($_GET['AccountNumber']); ?> <html> <body> <div> <?php if ($user_info === false){ $Output = 'http://www.MyDomain.Com/'; echo '<META HTTP-EQUIV=Refresh CONTENT="0; URL='.$Output.'">'; }else{ ?> <center> <title><?php echo $user_info['FirstName'], ' ', $user_info['LastName'], ' - ', $user_info['City'], ', ', $user_info['State']; ?> - Name of site</title> So basically what this code is allowing me to do is have a file called Profile.php And when a user visits this this page it will return the data Like this http://MyDomain.com/Profile.php?AccountNumber=50b9c965b7c3b How can I do this securely cause right now its using a get method really unsafe to retive the account number from the url bar.

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• Deserialization of a DataSet... deal with column name changes? how to migrate data from one column to another?

  - by Brian Kennedy

  So, we wanted to slightly generalize a couple columns in our typed dataset... basically dropped a foreign key constraint and then wanted to change a couple column names to better reflect their new state. All that is easy. The problem is that our users may have serialized out the old version of the DataSet as XML. We want to be able to read those old XML files and deserialize them into the revised DataSet. It seems that would be a fairly common desire... but I haven't yet figured out the right thing to search the internet for. One possible solution would seem to be some way to give a DataColumn an alias or alternate name such that when it reads the old column name, it knows that data can be read into the column with the new column name. I can find no support for any such thing. Another approach would seem to be an "after deserialization" method of some sort... so, I would let it read in the old column values into a normal DataColumn with that name, and then in the "after deserialization" method I would just move the data from the obsolete column into the new column, and then delete the old columns. That would seem to generalize to many other situations... and having such events or hooks is pretty common in ADO.NET. But I have looked for such a hook and haven't yet found it. If no "after deserialization" hook, it would seem I ought to be able to override ReadXml or ReadXmlSerializable methods to call the base and then do my "after" stuff to fix up old data into new. But it does not appear that is possible. Soooo, I have to think backward compatibility with old serialized DataSets and simple data migration would be a well-solved problem... so, trying to reinvent that wheel seems silly. But so far, I haven't seemed to find any documentation on doing those things. Suggestions? What is best practice for this?

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• Changing pointer of self

  - by rob5408

  I have an object that I alloc/init like normal just to get a instance. Later in my application I want to load state from disk for that object. I figure I could unarchive my class (which conforms to NSCoding) and just swap where my instance points to. To this end I use this code... NSString* pathForDataFile = [self pathForDataFile]; if([[NSFileManager defaultManager] fileExistsAtPath:pathForDataFile] == YES) { NSLog(@"Save file exists"); NSData *data = [[NSMutableData alloc] initWithContentsOfFile:pathForDataFile]; NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; [data release]; Person *tempPerson = [unarchiver decodeObjectForKey:@"Person"]; [unarchiver finishDecoding]; [unarchiver release]; if (tempPerson) { [self release]; self = [tempPerson retain]; } } Now when I sprinkled some NSLogs throughout my application I noticed self.person: <Person: 0x3d01a10> (After I create the object with alloc/init) self: <Person: 0x3d01a10> (At the start of this method) tempPerson: <Person: 0x3b1b880> (When I create the tempPerson) self: <Person: 0x3b1b880> (after i point self to the location of the tempPerson) self.person: <Person: 0x3d01a10> (After the method back in the main program) What am I missing?

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• Javascript code refactoring and assessment

  - by neitony

  I'm using javascript to toggle the display state of some objects based on the time of day. A sample of the code is given below. I was wondering if anyone could give a suggestion as to how I can refactor this code while at the same time improving the logic. switch(tcode) { case 'eur' : eur.setAttribute('style', 'display:block; opacity:0.5'); us.style.display = 'none'; asia.style.display = 'none'; us_inactive.style.display = 'block'; asia_inactive.style.display = 'block'; break; case 'us' : us.style.display = 'block'; eur.style.display = 'none'; asia.style.display = 'none'; eur_inactive.style.display = 'block'; asia_inactive.style.display = 'block'; break; case 'asia' : asia.setAttribute('style', 'display:block; opacity:0.5'); us.style.display = 'none'; eur.style.display = 'none'; eur_inactive.style.display = 'block'; us_inactive.style.display = 'block';

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