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  • Is there an established or defined best practice for source control branching between development and production builds?

    - by Matthew Patrick Cashatt
    Thanks for looking. I struggled in how to phrase my question, so let me give an example in hopes of making more clear what I am after: I currently work on a dev team responsible for maintaining and adding features to a web application. We have a development server and we use source control (TFS). Each day everyone checks in their code and when the code (running on the dev server) passes our QA/QC program, it goes to production. Recently, however, we had a bug in production which required an immediate production fix. The problem was that several of us developers had code checked in that was not ready for production so we had to either quickly complete and QA the code, or roll back everything, undo pending changes, etc. In other words, it was a mess. This made me wonder: Is there an established design pattern that prevents this type of scenario. It seems like there must be some "textbook" answer to this, but I am unsure what that would be. Perhaps a development branch of the code and a "release-ready" or production branch of the code?

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  • Performance of concurrent software on multicore processors

    - by Giorgio
    Recently I have often read that, since the trend is to build processors with multiple cores, it will be increasingly important to have programming languages that support concurrent programming in order to better exploit the parallelism offered by these processors. In this respect, certain programming paradigms or models are considered well-suited for writing robust concurrent software: Functional programming languages, e.g. Haskell, Scala, etc. The actor model: Erlang, but also available for Scala / Java (Akka), C++ (Theron, Casablanca, ...), and other programming languages. My questions: What is the state of the art regarding the development of concurrent applications (e.g. using multi-threading) using the above languages / models? Is this area still being explored or are there well-established practices already? Will it be more complex to program applications with a higher level of concurrency, or is it just a matter of learning new paradigms and practices? How does the performance of highly concurrent software compare to the performance of more traditional software when executed on multiple core processors? For example, has anyone implemented a desktop application using C++ / Theron, or Java / Akka? Was there a boost in performance on a multiple core processor due to higher parallelism?

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  • Should I expect my team to have more than a basic proficiency with our source control system?

    - by Joshua Smith
    My company switched from Subversion to Git about three months ago. We had weeks of advance notice prior to the switch. Since I'd never used Git before (or any other DVCS), I read Pro Git and spent a little time spinning up my own repositories and playing around, so that when we switched I'd be able to keep working with minimal pain. Now I'm the 'Git guy' by default. With a couple of exceptions, most of my team still has no idea how Git works. For example, they still think of branches as complete copies of the source code, and even go so far as to clone the repo into multiple folders (one per branch). They generally look at Git as a scary black box. Given the fundamental nature of source control in our daily work (not to mention the ridiculous amount of power Git affords us), I'm of the opinion that any dev who doesn't achieve a certain level of proficiency with it is a liability. Should I expect my team to have at least some understanding of how Git works internally, and how to use it beyond the most basic pull/merge/push operations? Or am I just making something out of nothing?

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  • Can Clojure's thread-based agents handle c10k performance?

    - by elliot42
    I'm writing a c10k-style service and am trying to evaluate Clojure's performance. Can Clojure agents handle this scale of concurrency with its thread-based agents? Other high performance systems seem to be moving towards async-IO/events/greenlets, albeit at a seemingly higher complexity cost. Suppose there are 10,000 clients connected, sending messages that should be appended to 1,000 local files--the Clojure service is trying to write to as many files in parallel as it can, while not letting any two separate requests mangle the same single file by writing at the same time. Clojure agents are extremely elegant conceptually--they would allow separate files to be written independently and asynchronously, while serializing (in the database sense) multiple requests to write to the same file. My understanding is that agents work by starting a thread for each operation (assume we are IO-bound and using send-off)--so in this case is it correct that it would start 1,000+ threads? Can current-day systems handle this number of threads efficiently? Most of them should be IO-bound and sleeping most of the time, but I presume there would still be a context-switching penalty that is theoretically higher than async-IO/event-based systems (e.g. Erlang, Go, node.js). If the Clojure solution can handle the performance, it seems like the most elegant thing to code. However if it can't handle the performance then something like Erlang or Go's lightweight processes might be preferable, since they are designed to have tens of thousands of them spawned at once, and are only moderately more complex to implement. Has anyone approached this problem in Clojure or compared to these other platforms? (Thanks for your thoughts!)

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  • How to keep background requests in sequence

    - by Jason Lewis
    I'm faced with implementing interfaces for some rather archaic systems, for handling online deposits to stored value accounts (think campus card accounts for students). Here's my dilemma: stage 1 of the process involves passing the user off to a thrid-party site for the credit card transaction, like old-school PayPal. Step two involves using a proprietary protocol for communicating with a legacy system for conducting the actual deposit. Step two requires that each transaction have a unique sequence number, and that the requests' seqnums are in order. Since we're logging each transaction in Postgres, my first thought was to take a number from a sequence in the DB, guaranteeing uniqueness. But since we're dealing with web requests that might come in near-simultaneously, and since latency with the return from the off-ste payment processor is beyond our control, there's always the chance for a race condition in the order of requests passed back to the proprietary system, and if the seqnums are out of order, the request fails silently (brilliant, right?). I thought about enqueuing the requests in Redis and using Resque workers to process them (single worker, single process, so they are processed in order), but we need to be able to give the user feedback as to whether the transaction was processed successfully, so this seems less feasible to me. I've tried to make this application handle concurrency well (as much as possible for a Ruby on Rails app), but now we're in a situation where we have to interact with a system that is designed to be single process, single threaded, and sequential. If it at least gave an "out of order" error, I could just increment (or take the next value off the sequence), but it's designed to fail silently in the event of ANY error. We are handling timeouts in a way that blocks on I/O, but since the application uses multiple workers (Unicorn), that's no guarantee. Any ideas/suggestions would be appreciated.

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  • Uses of persistent data structures in non-functional languages

    - by Ray Toal
    Languages that are purely functional or near-purely functional benefit from persistent data structures because they are immutable and fit well with the stateless style of functional programming. But from time to time we see libraries of persistent data structures for (state-based, OOP) languages like Java. A claim often heard in favor of persistent data structures is that because they are immutable, they are thread-safe. However, the reason that persistent data structures are thread-safe is that if one thread were to "add" an element to a persistent collection, the operation returns a new collection like the original but with the element added. Other threads therefore see the original collection. The two collections share a lot of internal state, of course -- that's why these persistent structures are efficient. But since different threads see different states of data, it would seem that persistent data structures are not in themselves sufficient to handle scenarios where one thread makes a change that is visible to other threads. For this, it seems we must use devices such as atoms, references, software transactional memory, or even classic locks and synchronization mechanisms. Why then, is the immutability of PDSs touted as something beneficial for "thread safety"? Are there any real examples where PDSs help in synchronization, or solving concurrency problems? Or are PDSs simply a way to provide a stateless interface to an object in support of a functional programming style?

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  • Broken package ubuntuone-control-panel-qt

    - by baale7
    An interrupted installation of updates resulted in ubuntuone-control-panel-qt breaking and now I cannot install or update anything. There seems to be an error in python2.7 - ImportError: No module named _sysconfigdata_nd dpkg: error processing archive ubuntuone-control-panel-qt_13.09-0ubuntu1_all.deb (--install): When I try to reinstall the package via .deb a dpkg --audit yields: The following packages are in a mess due to serious problems during installation. They must be reinstalled for them (and any packages that depend on them) to function properly: ?python-pexpect Python module for automating interactive applications ?ubuntuone-control-panel-qt Ubuntu One Control Panel - Qt frontend ?hplip-data HP Linux Printing and Imaging - data files ?python-libxml2 Python bindings for the GNOME XML library ?apport automatically generate crash reports for debugging The following packages are only half configured, probably due to problems configuring them the first time. The configuration should be retried using dpkg --configure or the configure menu option in dselect: ?python-ubuntuone-client Ubuntu One client Python libraries ?python-ubuntuone-control-panel Ubuntu One Control Panel - Python Libraries --configure or --configure -a doesn't work Any help?

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  • Plugins in Ops Center and Cloud Control

    - by Owen Allen
    Cloud Control just released an updated plugin for Oracle Virtual Networking, so I thought I'd mention a bit about how both Ops Center and Cloud Control use plugins. On the Ops Center side, we have a plugin to connect Ops Center to Cloud Control, letting them share monitoring data. This guide explains how to install and use that plugin. In Cloud Control, they have a more extensive collection of plugins, letting you link Cloud Control with a variety of other products. The Cloud Control library plug-in tab goes into more detail about how you can use these plugins in your environment.

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  • WebBrowser control won't display an https site that IE8 on the same PC will

    - by Velika
    In IE8, I get the follow warning, but if I choose to continue the site displays properly. There is a problem with this website's security certificate. The security certificate presented by this website was issued for a different website's address. Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server. We recommend that you close this webpage and do not continue to this website. Click here to close this webpage. Continue to this website (not recommended). More information In the WebBrowser control, I get this at first: Navigation to the webpage was canceled What you can try: Refresh the page. When I hit the refresh teh page, this time, I get the same wanting as I originally get in IE8, but when I click "Continue to this website (not recommended)", the page refresh again, displaying the same warning. What can I do to get the site to display in the WebBrowser control as it does in IE8. I would've thought that the control would be using the same core logic and therefore expected the same result.

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  • Error using ASP.NET 3.5 Chart control within a Repeater control

    - by tuseau
    Hi, I'm getting the error "Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerServerErrorException: Error executing child request for ChartImg.axd" at runtime from my Chart control. I have read one solution to this error message as documented here: http://social.msdn.microsoft.com/Forums/en-US/MSWinWebChart/thread/1dc4b352-c9a5-49dc-8f35-9b176509faa1/ but this does not solve my problem. I have the Chart within a Repeater control, which is within an ajax UpdatePanel. When I take the chart out of the Repeater (but leave it in the UpdatePanel), it works. So I'm thinking it is to do with the Repeater. Anyone got any ideas? Thanks in advance.

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  • Source Control - XCode - Visual Studio 2005/2008 / 2010

    - by Mick Walker
    My apologies if this has been asked before, I wasnt quite sure if this question should be asked on a programming forum, as it more relates to programming environment than a particular technology, so please accept my (double) appologies if I am posting this in the wrong place, my logic in this case was if it effects the code I write, then this is the place for it. At home, I do a lot of my development on a Mac Pro, I do development for the Mac, iPhone and Windows on this machine (Xcode & Visual Studio - (multiple versions installed in bootcamp, but generally I run it via Parallels)). When visiting a client, I have a similar setup, but on my MacBook Pro. What I want is a source control solution to install on the Mac Pro, that will support both XCode and multiple versions of visual studio, so that when I visit a client, I can simply grab the latest copy from source control via the MacBook Pro. Whilst visiting the client, he / she may suggest changes, and minor ones I would tend to make on site, so I need the ability to merge any modified code back into the trunk of the project / solution when I return home. At the moment, I am using no source control at all, and rely on simply coping folders and overwriting them when I return from a client- thats my 'merge'!!! I was wondering if anyone had any ideas of a source provider I could use, which would support both Windows and Mac development environments, and is cheap (free would be better).

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  • Using a version control system as a data backend

    - by JacobM
    I'm involved in a project that, among other things, involves storing edits and changes to a large hierarchical document (HTML-formatted text). We want to include versioning of textual changes and of structural changes. Currently we're maintaining the tree of document sections in a relational database, but as we start working on how to manage versioning of structural changes, it's clear that we're in danger of having to write a lot of the functionality that a version control system provides. We don't want to reinvent the wheel. Is it possible that we could use an existing version control system as the data store, at least for the document itself? Presumably we could do so by writing out new versions to the filesystem, and keeping that directory under version control (and programmatically doing commits and so forth) but it would be better if we could directly interact with the repository via code. The VCS that we are most familiar with is Subversion, but I'm not thrilled with how Subversion represents changes to the directory structure -- it would be nice if we could see that a particular revision included moving a section from Chapter 2 to Chapter 6, rather than just seeing a new version of the tree. This sounds more like the way a system like Mercurial handles changes to the structure. Any advice? Do VCS's have public APIs and so forth? The project is in Java (with Spring) if it matters.

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  • User control always crashes Visual Studio

    - by NickAldwin
    I'm trying to open a user control in one of our projects. It was created, I believe, in VS 2003, and the project has been converted to VS2008. I can view the code fine, but when I try to load the designer view, VS stops responding and I have to close it with the task manager. I have tried leaving it running for several minutes, but it does not do anything. I ran "devenv /log" but didn't see anything unusual in the log. I can't find a specific error message anywhere. Any idea what the problem might be? Is there a lightweight editing mode I might be able to use or something? The reason I need to have a look at the visual representation of this control is to decide where to insert some new components. I've tried googling it and searching SO, but either I don't know what to search or there is nothing out there about this. Any help is appreciated. (The strangest thing is that the user control seems to load fine in another project which references, but VS crashes as soon as I even so much as click on it in that project.)

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  • KERN-EXEC 3 when navigating within a text box (Symbian OS Browser Control)

    - by Andrew Flanagan
    I've had nothing but grief using Symbian's browser control on S60 3rd edition FP1. We currently display pages and many things are working smoothly. However, when inputting text into an HTML text field, the user will get a KERN-EXEC 3 if they move left at the beginning of the text input area (which should "wrap" it to the end) or if they move right at the end of the text input area (which should "wrap" it to the beginning). I can't seem to trap the input in OfferKeyEventL. I get the key event, I return EKeyWasConsumed and the cursor still moves. TKeyResponse CMyAppContainer::OfferKeyEventL(const TKeyEvent& aKeyEvent, TEventCode aType) { if (iBrCtlInterface) // My browser control { TBrCtlDefs::TBrCtlElementType type = iBrCtlInterface->FocusedElementType(); if (type == TBrCtlDefs::EElementActivatedInputBox || type == TBrCtlDefs::EElementInputBox) { if (aKeyEvent.iScanCode == EStdKeyLeftArrow || aKeyEvent.iScanCode == EStdKeyRightArrow) { return EKeyWasConsumed; } } } } I would be okay with completely disabling arrow key navigation but can't seem to do this. Any ideas? Am I going about this the wrong way? Has anyone here even worked with the Browser Control library (browserengine.lib) on S60 3.1?

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  • Gamepad Control for Processing + Android to Control Arduino Robot

    - by Iker
    I would like to create a Multitouch Gamepad control for Processing and use it to control a remote Arduino Robot. I would like to make the GUI on Processing and compile it for Android. Here is the GUI Gamepad for Processing I have created so far: float easing = 0.09; // start position int posX = 50; int posY = 200; // target position int targetX = 50; int targetY = 200; boolean dragging = false; void setup() { size(500,250); smooth(); } void draw() { background(255); if (!dragging) { // calculate the difference in position, apply easing and add to vx/vy float vx = (targetX - (posX)) * easing; float vy = (targetY - (posY)) * easing; // Add the velocity to the current position: make it move! posX += vx; posY += vy; } if(mousePressed) { dragging = true; posX = mouseX; posY = mouseY; } else { dragging = false; } DrawGamepad(); DrawButtons(); } void DrawGamepad() { //fill(0,155,155); //rect(0, 150, 100, 100, 15); ellipseMode(RADIUS); // Set ellipseMode to RADIUS fill(0,155,155); // Set fill to blue ellipse(50, 200, 50, 50); // Draw white ellipse using RADIUS mode ellipseMode(CENTER); // Set ellipseMode to CENTER fill(255); // Set fill to white// ellipse(posX, posY, 35, 35); // Draw gray ellipse using CENTER mode } void DrawButtons() { fill(0,155,155); // Set fill to blue ellipse(425, 225, 35, 35); ellipse(475, 225, 35, 35); fill(255,0,0); // Set fill to blue ellipse(425, 175, 35, 35); ellipse(475, 175, 35, 35); } I have realized that probably that code will not support Multitouch events on Android so I came up with another code found on this link Can Processing handle multi-touch? So the aim of this project is to create de multitouch gamepad to use to control my Arduino Robot. The gamepad should detect which key was pressed as well as the direction of the Joystick. Any help appreciated.

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  • Best source control system for maintaining different versions

    - by dalecooper
    Hi all! We need to be able to simultanously maintain a set of different versions of our system. I assume this is best done using branching. We currently use TFS2008 for source control, work items and automatic builds. What is the best version control solution for this task? Our organization is in the process of merging to TFS2010. Will TFS2010 give us the functionality we need to easily manage a series of branches per system version. We need to be able to keep each version isolated from the others, so that we can do testing deployment for each version. Our dev team consists of 5 .net developers and two flash developers. I have heard a lot of talk about GIT. Should we consider using GIT instead of TFS for source control? Is it possible to use TFS2010 together with GIT? Does anyone have similar setups that works nicely? Any sugggestions are appreciated! Thanks, Kjetil.

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  • Stored Procedures In Source Control - Automate Build/Deployment Process

    - by Alex
    My company provides a large .NET service-oriented solution. The services layer interact with a T-SQL back-end consisting of hundreds of tables and stored procedures. Our C# code is in version-control (SVN) but our stored procedures and schema are not. After much lobbying of expedient upper-management, I was allowed to review our (non-existent) build/deployment process to accomplish the following goals: Place schema and stored procedures under source-control. Automate the build/deployment process. I would like to proceed per the accepted answer's strategy in this post but have additional questions: I would like to use Hudson as my build server. Is this a reasonable choice for a C#/SQL solution? What better alternatives should I explore? Assuming I have all triggers, stored-procedures, schema, etc... under source control, and that they are scripted to individual files, how do I generate a build script which will take into account dependencies/references between these items? (SQL Server does this automatically, but it generates one giant script) What does the workflow of performing an update at the client look like? i.e. I have to keep existing table data. How do I roll-back schema changes? I am the only programmer. Several other pseudo-technical staff like to make changes directly inside SQL Management Studio. Is it realistic to expect others to adhere to this solution -- how can I enforce this? Thank you in advance for your help.

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  • Are there deprecated practices for multithread and multiprocessor programming that I should no longer use?

    - by DeveloperDon
    In the early days of FORTRAN and BASIC, essentially all programs were written with GOTO statements. The result was spaghetti code and the solution was structured programming. Similarly, pointers can have difficult to control characteristics in our programs. C++ started with plenty of pointers, but use of references are recommended. Libraries like STL can reduce some of our dependency. There are also idioms to create smart pointers that have better characteristics, and some version of C++ permit references and managed code. Programming practices like inheritance and polymorphism use a lot of pointers behind the scenes (just as for, while, do structured programming generates code filled with branch instructions). Languages like Java eliminate pointers and use garbage collection to manage dynamically allocated data instead of depending on programmers to match all their new and delete statements. In my reading, I have seen examples of multi-process and multi-thread programming that don't seem to use semaphores. Do they use the same thing with different names or do they have new ways of structuring protection of resources from concurrent use? For example, a specific example of a system for multithread programming with multicore processors is OpenMP. It represents a critical region as follows, without the use of semaphores, which seem not to be included in the environment. th_id = omp_get_thread_num(); #pragma omp critical { cout << "Hello World from thread " << th_id << '\n'; } This example is an excerpt from: http://en.wikipedia.org/wiki/OpenMP Alternatively, similar protection of threads from each other using semaphores with functions wait() and signal() might look like this: wait(sem); th_id = get_thread_num(); cout << "Hello World from thread " << th_id << '\n'; signal(sem); In this example, things are pretty simple, and just a simple review is enough to show the wait() and signal() calls are matched and even with a lot of concurrency, thread safety is provided. But other algorithms are more complicated and use multiple semaphores (both binary and counting) spread across multiple functions with complex conditions that can be called by many threads. The consequences of creating deadlock or failing to make things thread safe can be hard to manage. Do these systems like OpenMP eliminate the problems with semaphores? Do they move the problem somewhere else? How do I transform my favorite semaphore using algorithm to not use semaphores anymore?

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  • Are there any good Java/JVM libraries for my Expression Tree architecture?

    - by Snuggy
    My team and I are developing an enterprise-level application and I have devised an architecture for it that's best described as an "Expression Tree". The basic idea is that the leaf nodes of the tree are very simple expressions (perhaps simple values or strings). Nodes closer to the trunk will get more and more complex, taking the simpler nodes as their inputs and returning more complex results for their parents. Looking at it the other way, the application performs some task, and for this it creates a root expression. The root expression divides its input into smaller units and creates child expressions, which when evaluated it can use to build it's own result. The subdividing process continues until the simplest leaf nodes. There are two very important aspects of this architecture: It must be possible to manipulate nodes of the tree after it is built. The nodes may be given new input values to work with and any change in result for that node needs to be propagated back up the tree to the root node. The application must make best use of available processors and ultimately be scalable to other computers in a grid or in the cloud. Nodes in the tree will often be updating concurrently and notifying other interested nodes in the tree when they get a new value. Unfortunately, I'm not at liberty to discuss my actual application, but to aid understanding a little bit, you might imagine a kind of spreadsheet application being implemented with a similar architecture, where changes to cells in the table are propagated all over the place to other cells that need the result. The spreadsheet could get so massive that applying multi-core multi-computer distributed system to solve it would be of benefit. I've got my prototype "Expression Engine" working nicely on a single multi-core PC but I've started to run into a few concurrency issues (as expected because I haven't been taking too much care so far) so it's now time to start thinking about migrating the Engine to a more robust library, and that leads to a number of related questions: Is there any precedent for my "Expression Tree" architecture that I could research? What programming concepts should I consider. I realise this approach has many similarities to a functional programming style, and I'm already aware of the concepts of using futures and actors. Are there any others? Are there any languages or libraries that I should study? This question is inspired by my accidental discovery of Scala and the Akka library (which has good support for Actors, Futures, Distributed workloads etc.) and I'm wondering if there is anything else I should be looking at as well?

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  • Silverlight 4 OOB application access HTML DOM of the page in WebBrowser control

    - by Mike Weerasinghe
    Does anybody know if it is possible to access and manipulate an element in the html page that is rendered by the Silverlight 4 WebBrowser control. The scenario is like this. The user launches a Silverlight OOB application with elevated trust. The user manipulates some data in the application but must submit part of the data to an external web site. If I open the external site in a WebBrowser control, is there any way I can assist the user by pre filling some information in the external sites' web form via programmatic access to the DOM?

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  • Accessing html form input type=text using jquery from a windows forms webbrowser-control

    - by simply-tom
    I have two elements on my Windows Forms application: Webbrowser-Control Button Inside of the webbrowser-control I show a very simple html-form with two input type=text. I press the button and get access to both text fields. Last year at the Qt developer conference there was a quite good presentation: http://labs.trolltech.com/blogs/2009/04/17/jquery-and-qwebelement/ void highlightAllLinks() { QString code = "$('a').each( function () { $(this).css('background-color', 'yellow') } )"; view-page()-mainFrame()-evaluateJavaScript(code); } But I have to do this with .net and Windows Forms. Anyone knowing a good tutorial? Best regards,Tom

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  • How to Clear an image control in WPF (C#)

    - by antongladchenko
    I have an image control with a source image located in my c drive. I get a message that the image is being used by another process whenever I try to delete the original image to change it with another one dynamically. How do I release the image from the image control to be able to delete it. I tried this variants: string path = ((BitmapImage)img.Source).UriSource.LocalPath; img.SetValue(System.Windows.Controls.Image.SourceProperty, null); File.Delete(path); And: string path = ((BitmapImage)img.Source).UriSource.LocalPath; img.Source = null; File.Delete(path) But it's not work...

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