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  • ASP.NET MVC Image refreshing

    - by user295541
    Hi, I have an Employee object which has an image property. Image class contains image metadata as image caption, and image file name. If I upload a new image for an employee on async way without full post back the new image is not appeared on the page. I use GUID to name the image file to avoid the page caching. I do the image modifying the following way: ctrEmployee employee = Repository.Get(PassedItemID); if (employee.ctrImage != null) { string fullFileName = serverFolder + employee.ctrImage.FileName; FileInfo TheFile = new FileInfo(fullFileName); if (TheFile.Exists) { TheFile.Delete(); } fileName = Guid.NewGuid() + ".jpg"; employee.ctrImage.FileName = fileName; } resizedBmp.Save(string.Format("{0}{1}", serverFolder, fileName), System.Drawing.Imaging.ImageFormat.Jpeg); Repository.Edit<ctrEmployee>(employee); ImageID = employee.Image.Value; return PartialView(UserControlPaths.Thumbnail, new ThumbnailDataModel(employee.Image.Value, 150, 150)); The partial view has an image tag which gets the saved image url string which is a GUID. Anybody has an idea what I do wrong?

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  • Delphi: Alternative to using Assign/ReadLn for text file reading

    - by Ian Boyd
    i want to process a text file line by line. In the olden days i loaded the file into a StringList: slFile := TStringList.Create(); slFile.LoadFromFile(filename); for i := 0 to slFile.Count-1 do begin oneLine := slFile.Strings[i]; //process the line end; Problem with that is once the file gets to be a few hundred megabytes, i have to allocate a huge chunk of memory; when really i only need enough memory to hold one line at a time. (Plus, you can't really indicate progress when you the system is locked up loading the file in step 1). The i tried using the native, and recommended, file I/O routines provided by Delphi: var f: TextFile; begin Assign(filename, f); while ReadLn(f, oneLine) do begin //process the line end; Problem withAssign is that there is no option to read the file without locking (i.e. fmShareDenyNone). The former stringlist example doesn't support no-lock either, unless you change it to LoadFromStream: slFile := TStringList.Create; stream := TFileStream.Create(filename, fmOpenRead or fmShareDenyNone); slFile.LoadFromStream(stream); stream.Free; for i := 0 to slFile.Count-1 do begin oneLine := slFile.Strings[i]; //process the line end; So now even though i've gained no locks being held, i'm back to loading the entire file into memory. Is there some alternative to Assign/ReadLn, where i can read a file line-by-line, without taking a sharing lock? i'd rather not get directly into Win32 CreateFile/ReadFile, and having to deal with allocating buffers and detecting CR, LF, CRLF's. i thought about memory mapped files, but there's the difficulty if the entire file doesn't fit (map) into virtual memory, and having to maps views (pieces) of the file at a time. Starts to get ugly. i just want Assign with fmShareDenyNone!

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  • Sysdeo Tomcat DevLoader - Hot deploy of java class causes whole application to restart

    - by Gala101
    Hi, I am using sysdeo tomcat plugin 3.2.1 with eclipse 3.5.1 (Galileo) and tomcat 5.5.23 on windows XP. I can get tomcat plugin working in eclipse, and have extracted devloader.zip into [tomcat]\server\classes. I have also updated the context and now it has this entry: <Context path="/myapp1" reloadable="true" docBase="F:\Work\eclipse_workspace\myapp1" workDir="F:\Work\eclipse_workspace\myapp1\work" > <Logger className="org.apache.catalina.logger.SystemOutLogger" verbosity="4" timestamp="true"/> <Loader className="org.apache.catalina.loader.DevLoader" reloadable="true" debug="1" useSystemClassLoaderAsParent="false" /> </Context> I have activated devloader (in Project Properties Tomcat Devloader Classpath) and have 'checked' all my classes and jars, I haven't 'checked' commons-loggin.jar jsp-api.jar, servlet-api.jar. So on launching tomcat via the plugin, I can get it running with devloader as shown in eclipse console view [DevLoader] Starting DevLoader [DevLoader] projectdir=F:\Work\eclipse_workspace\myapp1 [DevLoader] added file:/F:/Work/eclipse_workspace/myapp1/WEB-INF/classes/ [DevLoader] added file:/F:/Work/eclipse_workspace/myapp1/WEB-INF/lib/activation.jar However, if I even add a single System.out.println into any java file and save it, the whole application gets reloaded (takes ~80 sec) which is as good as stopping/starting tomcat itself. I've tried adding -Xdebug in JAVA_OPTS in the catalina.bat but no luck :( Can you please guide where I may be doing it wrong.. Please note that I can 'redeploy' the whole application on tomcat but that's not what I need, I am looking to be able to make small changes in java classes 'on-the-fly' while coding/debugging without having to wait for complete app restart. Another annoyance is that restarting tomcat/application causes the session/debug progress to be lost.. Can you please guide me how to go about it. PS: I am not using any ant/maven scripts explicitly, just relying on eclipse to do the build for me (which it does).

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  • Using a CALayer in UITableViewCell

    - by Brian
    On each cell of my table view I want to have a bar that the user can slide out from the right. On the bar I plan to have icons. So, to do this I subclassed UITableViewCell. On the cell I have implemented drawRect and in there I have already drawn a gradient and background color on the cell. From there, I can create a CALayer, give it a frame & background color, and add it as a sub layer to the Views subLayers array. I can do all that and it will display my layer on each UITableViewCell. I have added touch events to the cell so I can detect when the user touches the cell and for testing I have made it so when the user swipes, my CALayer gets wider. But the issue is, when the UITableView scrolls and reuses a cell whose CALayer has been widened, it doesn't recreate the CALayer. I have tried [myLayer setNeedsDisplay] and used the drawLayer:inContext method of its delegate and it doesn't get called. I have also tried telling call setNeedsDisplay on the cell in my UITableViewController hoping that that will cause a redraw, but it doesn't work. I'm not sure what I'm missing. I am new to CoreGraphics & CoreAnimation. I have read through the CoreAnimation Developers Guide, but I'm assuming I missing something. Any help would be great.

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  • how to make a explorer like logic in Obj C for iphone

    - by Ekra
    Hi friends, To make the query simple first we can take example:- If we open the explorer in our Windows desktop how it shows us the tree. As we keep on clicking the tree it get expanded and shows the file in it. The same way I want to show a explorer which gets expanded as the user clicks on it(I want to get the business logic the UI is simple). The information of the explorer i.e. which folder has what files come in a XML format to me. I have 2 options of getting the XML either I can get the whole XML at one query(but I guess this might slow the application if the XML is quite big). OR I can get the XML for every list like first only the root structure then if user clicks on any folder in root I can get the list(the files or folders inside that folder) of that particular folder. Now the question is What would be the approach to implement both the method and which would be the best. Should I need to create some dictionary to maintain the link of the files like which file is inside what. I am not able to get as how I would be able to link all the files. Any hint or direction would be highly appreciated. Thanks in advance

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  • mysql error in php

    - by fusion
    i'm trying to run this php code which should display a quote from mysql, but can't figure out where is it going wrong. the result variable is null or empty. can someone help me out. thanks! <?php include 'config.php'; // 'text' is the name of your table that contains // the information you want to pull from $rowcount = mysql_query("select count(*) as rows from quotes"); // Gets the total number of items pulled from database. while ($row = mysql_fetch_assoc($rowcount)) { $max = $row["rows"]; //print_r ($max); } // Selects an item's index at random $rand = rand(1,$max)-1; print_r ($rand); $result = mysql_query("select * from quotes limit $rand, 1") or die ('Error: '.mysql_error()); if (!$result or mysql_num_rows($result)) { echo "Empty"; } else{ while ($row = mysql_fetch_array($result)) { $randomOutput = $row['cQuotes']; echo '<p>' . $randomOutput . '</p>'; } }

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  • How does 'lazy' work?

    - by Matt Fenwick
    What is the difference between these two functions? I see that lazy is intended to be lazy, but I don't understand how that is accomplished. -- | Identity function. id :: a -> a id x = x -- | The call '(lazy e)' means the same as 'e', but 'lazy' has a -- magical strictness property: it is lazy in its first argument, -- even though its semantics is strict. lazy :: a -> a lazy x = x -- Implementation note: its strictness and unfolding are over-ridden -- by the definition in MkId.lhs; in both cases to nothing at all. -- That way, 'lazy' does not get inlined, and the strictness analyser -- sees it as lazy. Then the worker/wrapper phase inlines it. -- Result: happiness Tracking down the note in MkId.lhs (hopefully this is the right note and version, sorry if it's not): Note [lazyId magic] ~~~~~~~~~~~~~~~~~~~ lazy :: forall a?. a? -> a? (i.e. works for unboxed types too) Used to lazify pseq: pseq a b = a `seq` lazy b Also, no strictness: by being a built-in Id, all the info about lazyId comes from here, not from GHC.Base.hi. This is important, because the strictness analyser will spot it as strict! Also no unfolding in lazyId: it gets "inlined" by a HACK in CorePrep. It's very important to do this inlining after unfoldings are exposed in the interface file. Otherwise, the unfolding for (say) pseq in the interface file will not mention 'lazy', so if we inline 'pseq' we'll totally miss the very thing that 'lazy' was there for in the first place. See Trac #3259 for a real world example. lazyId is defined in GHC.Base, so we don't have to inline it. If it appears un-applied, we'll end up just calling it. I don't understand that because it refers to lazyId instead of lazy. How does lazy work?

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  • Django DRY Feeds

    - by Mandx
    I'm using the Django Feeds Framework and it's really nice, very intuitive and easy to use. But, I think there is a problem when creating links to feeds in HTML. For example: <link rel="alternate" type="application/rss+xml" title="{{ feed_title }}" href="{{ url_of_feed }}" /> Link's HREF attribute can be easily found out, just use reverse() But, what about the TITLE attribute? Where the template engine should look for this? Even more, what if the feed is build up dinamically and the title depends on parameters (like this)? I can't come up with a solution that "seems" DRY to me... All that I can come up with is using context processors o template tags, but it gets messy when the context procesor/template tag has to find parameters to construct the Feed class, and writing this I realize I don't even know how to create a Feed instance myself within the view. If I put all this logic in the view, it would not be just one view. Also, the value for TITLE would be in the view AND in the feed.

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  • Scrolling with two fingers with a UIScrollView

    - by Craig
    I have an app where my main view accepts both touchesBegan and touchesMoved, and therefore takes in single finger touches, and drags. I want to implement a UIScrollView, and I have it working, but it overrides the drags, and therefore my contentView never receives them. I'd like to implement a UIScrollview, where a two finger drag indicates a scroll, and a one finger drag event gets passed to my content view, so it performs normally. Do I need create my own subclass of UIScrollView? Here's my code from my appDelegate where I implement the UIScrollView. @implementation MusicGridAppDelegate @synthesize window; @synthesize viewController; @synthesize scrollView; - (void)applicationDidFinishLaunching:(UIApplication *)application { // Override point for customization after app launch //[application setStatusBarHidden:YES animated:NO]; //[window addSubview:viewController.view]; scrollView.contentSize = CGSizeMake(720, 480); scrollView.showsHorizontalScrollIndicator = YES; scrollView.showsVerticalScrollIndicator = YES; scrollView.delegate = self; [scrollView addSubview:viewController.view]; [window makeKeyAndVisible]; } - (void)dealloc { [viewController release]; [scrollView release]; [window release]; [super dealloc]; }

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  • function's return address is different from its supposed value, buffer overflow,

    - by ultrajohn
    Good day everyone! I’m trying to understand how buffer overflow works. I’m doing this for my project in a computer security course I’m taking. Right now, I’m in the process of determining the address of the function’s return address which I’m supposed to change to perform a buffer overflow attack. I’ve written a simple program based from an example I’ve read in the internet. What this program does is it creates an integer pointer that will be made to point to the address of the function return address in the stack. To do this, (granted I understand how a function/program variables get organized in the stack), I add 8 to the buffer variable’ address and set it as the value of ret. I’m not doing anything here that would change the address contained in the location of func’s return address. here's the program: Output of the program when gets excecuted: As you can see, I’m printing the address of the variables buffer and ret. I’ve added an additional statement printing the value of the ret variable (supposed location of func return address, so this should print the address of the next instruction which will get executed after func returns from execution). Here is the dump which shows the supposed address of the instruction to be executed after func returns. (Underlined in green) As you can see, that value is way different from the value printed contained in the variable ret. My question is, why are they different? (of course in the assumption that what I’ve done are all right). Else, what have I done wrong? Is my understanding of the program’s runtime stack wrong? Please, help me understand this. My project is due nextweek and I’ve barely touched it yet. I’m sorry if I’m being demanding, I badly need your help.

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  • Clipped UITextField with UITextFieldAlignmentRight

    - by Typeoneerror
    Got a small problem with UITextField. I have a simple UITextField and when I set the textAlignment property to "right", it gets clipped by 1-2 pixels. It looks shite so I'm hoping someone has an idea of how to remedy this. I've tried setting the frame to integers to prevent them from being on .5 pixels. - (UITextField *)textControlForSetting:(NSDictionary *)settings { CGRect frame = CGRectIntegral(CGRectMake(100.0f, 0.0f, 170.0f, 44.0f)); UITextField *textField = [[[UITextField alloc] initWithFrame:frame] autorelease]; NSString *defaultValue = [settings objectForKey:kDefaultValueKey]; NSString *currentValue = [prefs objectForKey:[settings objectForKey:kSettingKey]]; textField.tag = settingsCounter; textField.delegate = self; textField.textAlignment = UITextAlignmentRight; textField.font = [UIFont fontWithName:@"HelveticaNeue" size:14.0f]; textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; textField.placeholder = (currentValue != nil) ? currentValue : defaultValue; settingsCounter++; return textField; }

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  • jquery navbar active state stays through refresh

    - by bob
    Hello, I am building a web application and because it has a layout. I don't want to have to create a seperate navigation bar for each page. I am wondering if I can assign an active class to a link that gets clicked on my navbar which will keep the active class even after a page refresh. html <div id="navbar"> <ul id = "main_nav"> <li><%= link_to '', root_path, :class => "home" %></li> <li><%= link_to '', junklists_path, :class => "buy" %></li> <li><%= link_to '', post_junk_path, :class => "sell" %></li> <li><%= link_to '', contact_path, :class => "contact" %></li> </ul> </div> jquery $("#main_nav li a").click(function(){ $("#main_nav li a.active").removeClass('active'); $(this).stop().addClass('active'); }) What options do I have? Thanks in advance!

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  • ajax call to servlet puzzler

    - by vector
    Greetings! I'm having a problem getting a text value of a captcha from a servlet through ajax call. When my captcha gets created, its text value is written to session, but after refreshing the image itself though ajax call, I only get one old value of the text. Refreshing the image itself works ok, but I'm stuck getting the correct values from the session on subsequent call. On page reload I get both the new image and its new text value, no joy with ajax though. This works great for the image refresh: $("#asos").attr("src", "/ImageServlet?="+((new Date()).getTime()) ) This call to another method to get text value gives me old stuff: $.ajax({ url:"checkCaptcha", type:"GET", cache: false, success: function( data) { alert(data); } }); Any feedback will be appreciated. ps: here's the meat of the method getting the call: PrintWriter out = response.getWriter(); response.setContentType("text/html"); response.setDateHeader("Expires", 0 ); // Set standard HTTP/1.1 no-cache headers. response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate"); // Set IE extended HTTP/1.1 no-cache headers (use addHeader). response.addHeader("Cache-Control", "post-check=0, pre-check=0"); // Set standard HTTP/1.0 no-cache header. response.setHeader("Pragma", "no-cache"); out.print( request.getSession( ).getAttribute("randomPixValue") ); out.close();

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  • How to Create Deterministic Guids

    - by desigeek
    In our application we are creating Xml files with an attribute that has a Guid value. This value needed to be consistent between file upgrades. So even if everything else in the file changes, the guid value for the attribute should remain the same. One obvious solution was to create a static dictionary with the filename and the Guids to be used for them. Then whenever we generate the file, we look up the dictionary for the filename and use the corresponding guid. But this is not feasible coz we might scale to 100's of files and didnt want to maintain big list of guids. So another approach was to make the Guid the same based on the path of the file. Since our file paths and application directory structure are unique, the Guid should be unique for that path. So each time we run an upgrade, the file gets the same guid based on its path. I found one cool way to generate such 'Deterministic Guids' (Thanks Elton Stoneman). It basically does this: private Guid GetDeterministicGuid(string input) { //use MD5 hash to get a 16-byte hash of the string: MD5CryptoServiceProvider provider = new MD5CryptoServiceProvider(); byte[] inputBytes = Encoding.Default.GetBytes(input); byte[] hashBytes = provider.ComputeHash(inputBytes); //generate a guid from the hash: Guid hashGuid = new Guid(hashBytes); return hashGuid; } So given a string, the Guid will always be the same. Are there any other approaches or recommended ways to doing this? What are the pros or cons of that method?

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  • Calculation Expression Parser with Nesting and Variables in ActionScript

    - by yuletide
    Hi There, I'm trying to enable dynamic fields in the configuration file for my mapping app, but I can't figure out how to parse the "equation" passed in by the user, at least not without writing a whole parser from scratch! I'm sure there is some easier way to do this, and so I'm asking for ideas! Basic idea: public var testString:String = "(#TOTPOP_CY#-#HISPOP_CY#)/#TOTPOP_CY#"; public var valueObject:Object = {TOTPOP_CY:1000, HISPOP_CY:100}; public function calcParse(eq:String):String { // do calculations return calculatedValue } So far, I was thinking of splitting the expression by either the operators, or maybe the variable tokens, but that gets rid of the parenthetical nesting. Alternatively, use a series of regex to search and replace each piece of the expression with its value, recursively running until only a number is left. But I don't think regex does math (i.e. replace "\d + \d" with the sum of the two numbers) Ideally, I'd just do a find/replace all variable names with their values, then run an eval(), but there's no eval in AS... eesh I downloaded some course materials for a course on compiler design, so maybe I'll just write a full-fledged calculator language and parser and port it over from the OTHER flex (the parser generator) :-D

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  • C++ from SpeakHere in iPhone app

    - by niklassaers
    Hi guys, I've made a template app where I've grabbed the recording part of the SpeakHere example and removed the file handling part, but I'm struggeling to get the C++ part of the app working right. As soon as it enters the C++ class, it gets syntax errors. If I don't import the header files from C++ (and then of course don't use the code) into my Objective C classes, all works fine. I cannot see the difference between how I'm doing it and the example is doing it. Can you see the difference? I've posted the entire code here: http://github.com/niklassaers/testFFT The build errors I get are: testFFT/CAStreamBasicDescription.h:91:0 testFFT/CAStreamBasicDescription.h:91: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'CAStreamBasicDescription' testFFT/CAStreamBasicDescription.h:298:0 testFFT/CAStreamBasicDescription.h:298: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token testFFT/CAStreamBasicDescription.h:299:0 testFFT/CAStreamBasicDescription.h:299: error: expected '=', ',', ';', 'asm' or '__attribute__' before '==' token testFFT/CAStreamBasicDescription.h:301:0 testFFT/CAStreamBasicDescription.h:301: error: expected '=', ',', ';', 'asm' or '__attribute__' before '!=' token testFFT/CAStreamBasicDescription.h:302:0 testFFT/CAStreamBasicDescription.h:302: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<=' token testFFT/CAStreamBasicDescription.h:303:0 testFFT/CAStreamBasicDescription.h:303: error: expected '=', ',', ';', 'asm' or '__attribute__' before '>=' token testFFT/CAStreamBasicDescription.h:304:0 testFFT/CAStreamBasicDescription.h:304: error: expected '=', ',', ';', 'asm' or '__attribute__' before '>' token testFFT/CAStreamBasicDescription.h:307:0 testFFT/CAStreamBasicDescription.h:307: error: expected ';', ',' or ')' before '&' token testFFT/CAXException.h:65:0 testFFT/CAXException.h:65: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'CAX4CCString' testFFT/CAXException.h:87:0 testFFT/CAXException.h:87: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'CAXException' testFFT/AQRecorder.h:59:0 testFFT/AQRecorder.h:59: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'AQRecorder' testFFT/RecorderLink.h:57:0 testFFT/RecorderLink.h:57: error: expected specifier-qualifier-list before 'AQRecorder' testFFT/RecorderLink.h:62:0 testFFT/RecorderLink.h:62: error: expected specifier-qualifier-list before 'AQRecorder' Any idea what's going on here? Cheers Nik

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  • wait for CLLocationManager to finish before tweeting

    - by user295944
    I want to wait for latitude.text and longtitude.text to be filled in before sending a tweet, this code works fine, but I would rather not put the tweeting part in locationManager because I also want to sometimes update the current location without sending a tweet. How can I make sure the txt gets filled in before sending the tweet without doing this? - (IBAction)update { latitude.text =@""; longitude.text =@""; locmanager = [[CLLocationManager alloc] init]; [locmanager setDelegate:self]; [locmanager setDesiredAccuracy:kCLLocationAccuracyBest]; [locmanager startUpdatingLocation]; } - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { CLLocationCoordinate2D location = [newLocation coordinate]; latitude.text = [NSString stringWithFormat: @"%f", location.latitude]; longitude.text = [NSString stringWithFormat: @"%f", location.longitude]; TwitterRequest * t = [[TwitterRequest alloc] init]; t.username = @"****"; t.password = @"****"; [twitterMessageText resignFirstResponder]; loadingActionSheet = [[UIActionSheet alloc] initWithTitle:@"Posting To Twitter..." delegate:nil cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil]; [loadingActionSheet showInView:self.view]; [t statuses_update:twitterMessageText.text andLat:latitude.text andLong:longitude.text delegate:self requestSelector:@selector(status_updateCallback:)]; twitterMessageText.text=@""; }

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  • Hooking thread exit

    - by mackenir
    Is there a way for me to hook the exit of managed threads (i.e. run some code on a thread, just before it exits?) I've developed a mechanism for hooking thread exit that works for some threads. Step 1: develop a 'hook' STA COM class that takes a callback function and calls it in its destructor. Step 2: create a ThreadStatic instance of this object on the thread I want to hook, and pass the object a managed delegate converted to an unmanaged function pointer. The delegate then gets called on thread exit (since the CLR calls IUnknown::Release on all STA COM RCWs as part of thread exit). This mechanism works on, for example, worker threads that I create in code using the Thread class. However, it doesn't seem to work for the application's main thread (be it a console or windows app). The 'hook' COM object seems to be deleted too late in the shutdown process and the attempt to call the delegate fails. (The reason I want to implement this facility is so I can run some native COM code on the exiting thread that works with STA COM objects that were created on the thread, before it's 'too late' (i.e. before the thread has exited, and it's no longer possible to work with STA COM objects on that thread.))

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  • Importing MEF-Plugins into MVC Controllers

    - by Marks
    Hello. There are several examples of using MEF to plugin whole controller/view packages into a MVC application, but i didn't found one, using MEF to plugin funcional parts, used by other controllers. For example, think of a NewsService with a simple interface like interface INewsService { List<NewsItem> GetAllNews(); } That gets news wherever he wants, and returns them in a List of NewsItems. My page should load an exported INewsService and show the news on the page. But there is the problem. I cant just use [Import] in the controllers, as they are just created when they are needed. Edit: (Importing them to the main MVCApplication class doesn't work, becouse i cant access it from the controllers.) I think i found a way to access the main app via HttpContext.ApplicationInstance. But the Service object in this instance is null although it was created successfully in the Application_Start() method. Any idea why? So, how can i access the NewsService from within a controller? Thanks in advance, Marks

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  • MINA: Performing synchronous write requests / read responses

    - by Matt Huggins
    I'm attempting to perform a synchronous write/read in a demux-based client application with MINA 2.0 RC1, but it seems to get stuck. Here is my code: public boolean login(final String username, final String password) { // block inbound messages session.getConfig().setUseReadOperation(true); // send the login request final LoginRequest loginRequest = new LoginRequest(username, password); final WriteFuture writeFuture = session.write(loginRequest); writeFuture.awaitUninterruptibly(); if (writeFuture.getException() != null) { session.getConfig().setUseReadOperation(true); return false; } // retrieve the login response final ReadFuture readFuture = session.read(); readFuture.awaitUninterruptibly(); if (readFuture.getException() != null) { session.getConfig().setUseReadOperation(true); return false; } // stop blocking inbound messages session.getConfig().setUseReadOperation(false); // determine if the login info provided was valid final LoginResponse loginResponse = (LoginResponse)readFuture.getMessage(); return loginResponse.getSuccess(); } I can see on the server side that the LoginRequest object is retrieved, and a LoginResponse message is sent. On the client side, the DemuxingProtocolCodecFactory receives the response, but after throwing in some logging, I can see that the client gets stuck on the call to readFuture.awaitUninterruptibly(). I can't for the life of me figure out why it is stuck here based upon my own code. I properly set the read operation to true on the session config, meaning that messages should be blocked. However, it seems as if the message no longer exists by time I try to read response messages synchronously. Any clues as to why this won't work for me?

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  • Is This a Valid Way to Use Blocks in Objective-C?

    - by Carter
    I've been building a HTTP client that uses web services to synchronize information between the client and server. I've been using Blocks and NSURLConnection to achieve this on the client side, but I'm getting frequent EXC_BAD_ACCESS crashes in objc_msgSend(). From what I understand, this usually means that a stored block that has fallen off the stack has been called. I think I've coded things correctly to avoid this, but I'm still stuck. Here is conceptually what my code is doing. It starts by calling "synchronizeWithWebServer". That method invokes "listRootObjectsOnServerWithBlock:" which takes in a block to be called when the method returns. "listRootObjectsOnServersWithBlock:" initiates a NSURLConnection to the web server asynchronously. It to expects a block to be called when it returns. Inside that block I want to be able to execute the original Block (so aptly named 'block'). This is only a simplified version of my code. The real synchronization process is more complex but it's mostly more of the same as what you see below. Sometimes the code works perfectly, but about 80% of the time it crashes very early on in the routine. It seems to be more vulnerable to crashing when my data set gets larger. - (void)synchronizeWithWebServer { [self listRootObjectsOnServerWithBlock:^(NSArray *results, NSError *error) { //Iterate over result objects and perform some other similar routines. }]; } - (void)listRootObjectsOnServerWithBlock:(void (^)(NSArray *results, NSError *error))block { //Create NSURLRequest Here //Create connection asynchronously. block = [block copy]; [NSURLConnection sendAsynchronousRequest:urlRequest queue:[NSOperationQueue currentQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error){ //Parse response from web server (stored in NSData *data) NSArray *results = ..... //Call 'block' block(results, error); [block release]; }]; }

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  • How can I improve my real-time behavior in multi-threaded app using pthreads and condition variables

    - by WilliamKF
    I have a multi-threaded application that is using pthreads. I have a mutex() lock and condition variables(). There are two threads, one thread is producing data for the second thread, a worker, which is trying to process the produced data in a real time fashion such that one chuck is processed as close to the elapsing of a fixed time period as possible. This works pretty well, however, occasionally when the producer thread releases the condition upon which the worker is waiting, a delay of up to almost a whole second is seen before the worker thread gets control and executes again. I know this because right before the producer releases the condition upon which the worker is waiting, it does a chuck of processing for the worker if it is time to process another chuck, then immediately upon receiving the condition in the worker thread, it also does a chuck of processing if it is time to process another chuck. In this later case, I am seeing that I am late processing the chuck many times. I'd like to eliminate this lost efficiency and do what I can to keep the chucks ticking away as close to possible to the desired frequency. Is there anything I can do to reduce the delay between the release condition from the producer and the detection that that condition is released such that the worker resumes processing? For example, would it help for the producer to call something to force itself to be context switched out? Bottom line is the worker has to wait each time it asks the producer to create work for itself so that the producer can muck with the worker's data structures before telling the worker it is ready to run in parallel again. This period of exclusive access by the producer is meant to be short, but during this period, I am also checking for real-time work to be done by the producer on behalf of the worker while the producer has exclusive access. Somehow my hand off back to running in parallel again results in significant delay occasionally that I would like to avoid. Please suggest how this might be best accomplished.

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  • mtl, transformers, monads-fd, monadLib, and the paradox of choice

    - by yairchu
    Hackage has several packages for monad transformers: mtl: Monad transformer library transformers: Concrete functor and monad transformers monads-fd: Monad classes, using functional dependencies monads-tf: Monad classes, using type families monadLib: A collection of monad transformers. mtl-tf: Monad transformer library using type families mmtl: Modular Monad transformer library mtlx: Monad transformer library with type indexes, providing 'free' copies. compose-trans: Composable monad transformers (and maybe I missed some) Which one shall we use? mtl is the one in the Haskell Platform, but I keep hearing on reddit that it's uncool. But what's bad about choice anyway, isn't it just a good thing? Well, I saw how for example the authors of data-accessor had to make all these to cater to just the popular choices: data-accessor-monadLib library: Accessor functions for monadLib's monads data-accessor-monads-fd library: Use Accessor to access state in monads-fd State monad class data-accessor-monads-tf library: Use Accessor to access state in monads-tf State monad type family data-accessor-mtl library: Use Accessor to access state in mtl State monad class data-accessor-transformers library: Use Accessor to access state in transformers State monad I imagine that if this goes on and for example several competing Arrow packages evolve, we might see something like: spoonklink-arrows-transformers, spoonklink-arrows-monadLib, spoonklink-tfArrows-transformers, spoonklink-tfArrows-monadLib, ... And then I worry that if spoonklink gets forked, Hackage will run out of disk space. :) Questions: Why are there so many monad transformer packages? Why is mtl [considered] uncool? What are the key differences? Most of these seemingly competing packages were written by Andy Gill and are maintained by Ross Paterson. Does this mean that these packages are not competing but rather work together in some way? And do Andy and Ross consider any of their own packages as obsolete? Which one should me and you use?

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  • Designing a fluid Javascript interface to hide callback asynchrony

    - by Anurag
    How would I design an API to hide the asynchronous nature of AJAX and HTTP requests, or basically delay it to provide a fluid interface. To show an example from Twitter's new Anywhere API: // get @ded's first 20 statuses, filter only the tweets that // mention photography, and render each into an HTML element T.User.find('ded').timeline().first(20).filter(filterer).each(function(status) { $('div#tweets').append('<p>' + status.text + '</p>'); }); function filterer(status) { return status.text.match(/photography/); } vs this (asynchronous nature of each call is clearly visible) T.User.find('ded', function(user) { user.timeline(function(statuses) { statuses.first(20).filter(filterer).each(function(status) { $('div#tweets').append('<p>' + status.text + '</p>'); }); }); }); It finds the user, gets their tweet timeline, filters only the first 20 tweets, applies a custom filter, and ultimately uses the callback function to process each tweet. I am guessing that a well designed API like this should work like a query builder (think ORMs) where each function call builds the query (HTTP URL in this case), until it hits a looping function such as each/map/etc., the HTTP call is made and the passed in function becomes the callback. An easy development route would be to make each AJAX call synchronous, but that's probably not the best solution. I am interested in figuring out a way to make it asynchronous, and still hide the asynchronous nature of AJAX.

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  • Create a VPN with Python

    - by user213060
    I want to make a device "tunnel box" that you plug an input ethernet line, and an output ethernet line, and all the traffic that goes through it gets modified in a special way. This is similar to how a firewall, IDS, VPN, or similar boxes are connected inline in a network. I think you can just assume that I am writing a custom VPN in Python for the purpose of this question: LAN computer <--\ LAN computer <---> [LAN switch] <--> ["tunnel box"] <--> [internet modem] <--> LAN computer <--/ My question is, what is a good way to program this "tunnel box" from python? My application needs to see TCP flows at the network layer, not as individual ethernet frames. Non-TCP/IP traffic such as ICPM and other types should just be passed through. Example Twisted-like Code for my "tunnel box" tunnel appliance: from my_code import special_data_conversion_function class StreamInterceptor(twisted.Protocol): def dataReceived(self,data): data=special_data_conversion_function(data) self.outbound_connection.send(data) My initial guesses: TUN/TAP with twisted.pair.tuntap.py - Problem: This seems to only work at the ethernet frame level, not like my example? Socks proxy - Problem: Not transparent as in my diagram. Programs have to be specifically setup for it. Thanks!

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