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  • A little gem from MPN&ndash;FREE online course on Architectural Guidance for Migrating Applications to Windows Azure Platform

    - by Eric Nelson
    I know a lot of technical people who work in partners (ISVs, System Integrators etc). I know that virtually none of them would think of going to the Microsoft Partner Network (MPN) learning portal to find some deep and high quality technical content. Instead they would head to MSDN, Channel 9, msdev.com etc. I am one of those people :-) Hence imagine my surprise when i stumbled upon this little gem Architectural Guidance for Migrating Applications to Windows Azure Platform (your company and hence your live id need to be a member of MPN – which is free to join). This is first class stuff – and represents about 4 hours which is really 8 if you stop and ponder :) Course Structure The course is divided into eight modules.  Each module explores a different factor that needs to be considered as part of the migration process. Module 1:  Introduction:  This section provides an introduction to the training course, highlighting the values of the Windows Azure Platform for developers. Module 2:  Dynamic Environment: This section goes into detail about the dynamic environment of the Windows Azure Platform. This session will explain the difference between current development states and the Windows Azure Platform environment, detail the functions of roles, and highlight development considerations to be aware of when working with the Windows Azure Platform. Module 3:  Local State: This session details the local state of the Windows Azure Platform. This section details the different types of storage within the Windows Azure Platform (Blobs, Tables, Queues, and SQL Azure). The training will provide technical guidance on local storage usage, how to write to blobs, how to effectively use table storage, and other authorization methods. Module 4:  Latency and Timeouts: This session goes into detail explaining the considerations surrounding latency, timeouts and how to assess an IT portfolio. Module 5:  Transactions and Bandwidth: This session details the performance metrics surrounding transactions and bandwidth in the Windows Azure Platform environment. This session will detail the transactions and bandwidth costs involved with the Windows Azure Platform and mitigation techniques that can be used to properly manage those costs. Module 6:  Authentication and Authorization: This session details authentication and authorization protocols within the Windows Azure Platform. This session will detail information around web methods of authorization, web identification, Access Control Benefits, and a walkthrough of the Windows Identify Foundation. Module 7:  Data Sensitivity: This session details data considerations that users and developers will experience when placing data into the cloud. This section of the training highlights these concerns, and details the strategies that developers can take to increase the security of their data in the cloud. Module 8:  Summary Provides an overall review of the course.

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  • How do I disable Caps Lock by command line?

    - by Echogene
    For some reason my laptop is stuck in Caps Lock. I have the Caps Lock key mapped by xmodmap to hyper_l, so I don't have a caps_lock key to turn it off. Is there a way I can turn it off by command line? It would be nice if I could reset the lock state without resetting my computer, especially for future reference. This has happened before, but I would like to know now how to do it properly this time.

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  • Delay command execution over sockets

    - by David
    I've been trying to fix the game loop in a real time (tick delay) MUD. I realized using Thread.Sleep would seem clunky when the user spammed commands through their choice of client (Zmud, etc) e.g. east;south;southwest would wait three move ticks and then output everything from the past couple rooms. The game loop basically calls a Flush and Fill method for each socket during each tick (50ms) private void DoLoop() { Stopwatch stopWatch = new Stopwatch(); stopWatch.Start(); while (running) { // for each socket, flush and fill ConnectionMonitor.Update(); stopWatch.Stop(); WaitIfNeeded(stopWatch.ElapsedMilliseconds); stopWatch.Reset(); } } The Fill method fires the command events, but as mentioned before, they currently block using Thread.Sleep. I tried adding a "ready" flag to the state object that attempts to execute the command along with a queue of spammed commands, but it ends up executing one command and queuing up the rest i.e. each subsequent command executes something that got queued up that should've been executed before. I must be missing something about the timer. private readonly Queue<SpammedCommand> queuedCommands = new Queue<SpammedCommand>(); private bool ready = true; private void TryExecuteCommand(string input) { var commandContext = CommandContext.Create(input); var player = Server.Current.Database.Get<Player>(Session.Player.Key); var commandInfo = Server.Current.CommandLookup .FindCommand(commandContext.CommandName, player.IsAdmin); if (commandInfo != null) { if (!ready) { // queue command queuedCommands.Enqueue(new SpammedCommand() { Context = commandContext, Info = commandInfo }); return; } if (queuedCommands.Count > 0) { // queue the incoming command queuedCommands.Enqueue(new SpammedCommand() { Context = commandContext, Info = commandInfo, }); // dequeue and execute var command = queuedCommands.Dequeue(); command.Info.Command.Execute(Session, command.Context); setTimeout(command.Info.TickLength); return; } commandInfo.Command.Execute(Session, commandContext); setTimeout(commandInfo.TickLength); } else { Session.WriteLine("Command not recognized"); } } Finally, setTimeout was supposed to set the execution delay (TickLength) for that command, and makeReady just sets the ready flag on the state object to true. private void setTimeout(TickDelay tickDelay) { ready = false; var t = new System.Timers.Timer() { Interval = (long) tickDelay, AutoReset = false, }; t.Elapsed += makeReady; t.Start(); // fire this in tickDelay ms } // MAKE READYYYYY!!!! private void makeReady(object sender, System.Timers.ElapsedEventArgs e) { ready = true; } Am I missing something about the System.Timers.Timer created in setTimeout? How can I execute (and output) spammed commands per TickLength without using Thread.Sleep?

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  • Can't fix broken packages using Synaptic (Broken Package: Wine1.4)

    - by Rustyblade
    Ok so I am trying to fix a broken package in order to install wine. When I do "sudo apt-get install wine" I get: sam@ubuntu:~$ sudo apt-get install wine [sudo] password for sam: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wine : Depends: wine1.4 but it is not going to be installed E: Unable to correct problems, you have held broken packages. Then I try "sudo apt-get install wine1.4" sam@ubuntu:~$ sudo apt-get install wine1.4 Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wine1.4 : Depends: wine1.4-i386 (= 1.4.1-0ubuntu1) but it is not installable Recommends: gnome-exe-thumbnailer but it is not going to be installed or kde-runtime but it is not going to be installed Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages. So someone told me to try Synaptic. Here is what I tried: Searched wine Right clicked wine1.4 Said I needed to mark other packages Mark I click Apply. It says, You have to fix broken packages first! I do EditFix Broken Packages I get this E: Unable to correct problems, you have held broken packages. E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. E: Unable to correct dependencies E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. E: Unable to correct dependencies I am really frustrated. I removed the Official Wine PPA and tried it I even tried $ sudo apt-get -f install 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Please help me :( System: Ubuntu 12.10 64bit

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  • How to get lookahead symbol when constructing LR(1) NFA for parser?

    - by greenoldman
    I am reading an explanation (awesome "Parsing Techniques" by D.Grune and C.J.H.Jacobs; p.292 in the 2nd edition) about how to construct an LR(1) parser, and I am at the stage of building the initial NFA. What I don't understand is how to get/compute a lookahead symbol. Here is the example from the book, the grammar: S -> E E -> E - T E -> T T -> ( E ) T -> n n is terminal. The "weird" transitions for me are is the sequence: 1) S -> . E eof 2) E -> . E - T eof 3) E -> . E - T - 4) E -> E . - T - 5) E -> E - . T - (Note: In the above table, the state numbers are in front and the lookahead symbol is at the end.) What puzzles me is that transition from (4) to (5) means reading - token, right? So how is it that - is still a lookahead symbol and even more important why is it that eof is no longer a lookahead symbol? After all in an input such as n - n eof there is only one - symbol. My naive thinking tells me (5) should be written as: 5) E -> E - . T - eof And another thing -- n is terminal. Why it is not used at all as a lookahead symbol? I mean -- we expect to see - or (, it is ok, but lack of n means we are sure it won't appear in input? Update: after more reading I am only more confused ;-) I.e. what is really a lookahead? Because I see such state as (p.292, 2nd column, 2nd row): E -> E . - T eof Lookahead says eof but the incoming input says -. Isn't it a contradiction? And it is not only in this book.

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  • How to uninstall Ubuntu Software Center in 11.10?

    - by sainath
    I am trying to uninstall software center for ubuntu oneric using the command sudo apt-get remove software center and get this as result Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package software E: Unable to locate package center I did it once and got it fixed but now it does't work. I have an issue with the software center it keeps on repeatedly giving message saying send error.

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  • Are closures with side-effects considered "functional style"?

    - by Giorgio
    Many modern programming languages support some concept of closure, i.e. of a piece of code (a block or a function) that Can be treated as a value, and therefore stored in a variable, passed around to different parts of the code, be defined in one part of a program and invoked in a totally different part of the same program. Can capture variables from the context in which it is defined, and access them when it is later invoked (possibly in a totally different context). Here is an example of a closure written in Scala: def filterList(xs: List[Int], lowerBound: Int): List[Int] = xs.filter(x => x >= lowerBound) The function literal x => x >= lowerBound contains the free variable lowerBound, which is closed (bound) by the argument of the function filterList that has the same name. The closure is passed to the library method filter, which can invoke it repeatedly as a normal function. I have been reading a lot of questions and answers on this site and, as far as I understand, the term closure is often automatically associated with functional programming and functional programming style. The definition of function programming on wikipedia reads: In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. and further on [...] in functional code, the output value of a function depends only on the arguments that are input to the function [...]. Eliminating side effects can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming. On the other hand, many closure constructs provided by programming languages allow a closure to capture non-local variables and change them when the closure is invoked, thus producing a side effect on the environment in which they were defined. In this case, closures implement the first idea of functional programming (functions are first-class entities that can be moved around like other values) but neglect the second idea (avoiding side-effects). Is this use of closures with side effects considered functional style or are closures considered a more general construct that can be used both for a functional and a non-functional programming style? Is there any literature on this topic? IMPORTANT NOTE I am not questioning the usefulness of side-effects or of having closures with side effects. Also, I am not interested in a discussion about the advantages / disadvantages of closures with or without side effects. I am only interested to know if using such closures is still considered functional style by the proponent of functional programming or if, on the contrary, their use is discouraged when using a functional style.

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  • Built in webcam installation

    - by user291941
    I followed instructions for installing built in webcam but everytime after entering cmd and pwd a statement execute that "unable to locate package cheese"..plz help me out i need to submit my project within a week and still stuck here... This is what it is showing every time... wtc@ubuntu:~$ sudo apt-get install cheese [sudo] password for wtc: Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package cheese wtc@ubuntu:~$

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  • MVC Communication Pattern

    - by Kedu
    This is kind of a follow up question to this http://stackoverflow.com/questions/23743285/model-view-controller-and-callbacks, but I wanted to post it separately, because its kind of a different topic. I'm working on a multiplayer cardgame for the Android platform. I split the project into MVC which fits the needs pretty good, but I'm currently stuck because I can't figure out a good way to communicate between the different parts. I have everything setup and working with the controller being a big state machine, which is called over and over from the gameloop, and calls getter methods from the GUI and the android/network part to get the input. The input itself in the GUI and network is set by inputlisteners that set a local variable which I read in the getter method. So far so good, this is working. But my problem is, the controller has to check every input separately,so if I want to add an input I have to check in which states its valid and call the getter method from all these states. This is not good, and lets the code look pretty ugly, makes additions uncomfortable and adds redundance. So what I've got from the question I mentioned above is that some kind of command or event pattern will fit my needs. What I want to do is to create a shared and threadsafe queue in the controller and instead of calling all these getter methods, I just check the queue for new input and proceed it. On the other side, the GUI and network don't have all these getters, but instead create an event or command and send it to the controller through, for example, observer/observable. Now my problem: I can't figure out a way, for these commands/events to fit a common interface (which the queue can store) and still transport different kind of data (button clicks, cards that are played, the player id the command comes from, synchronization data etc.). If I design the communication as command pattern, I have to stick all the information that is needed to execute the command into it when its created, that's impossible because the GUI or network has no knowledge of all the things the controller needs to execute stuff that needs to be done when for example a card is played. I thought about getting this stuff into the command when executing it. But over all the different commands I have, I would need all the information the controller has, and thus give the command a reference to the controller which would make everything in it public, which is real bad design I guess. So, I could try some kind of event pattern. I have to transport data in the event. So, like the command, I would have an interface, which all events have in common, and can be stored in the shared queue. I could create a big enum with all the different events that a are possible, save one of these enums in the actual event, and build a big switch case for the events, to proceed different stuff for different events. The problem here: I have different data for all the events. But I need a common interface, to store the events in a queue. How do I get the specific data, if I can only access the event through the interface? Even if that wouldn't be a problem, I'm creating another big switch case, which looks ugly, and when i want to add a new event, I have to create the event itself, the case, the enum, and the method that's called with the data. I could of course check the event with the enum and cast it to its type, so I can call event type specific methods that give me the data I need, but that looks like bad design too.

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  • Microsoft Dog Food Days

    - by Chris Haaker
    There is a free two-day event called "Dog Food Conference 2012" being held at the Microsoft offices in Columbus, Ohio (home to my beloved Ohio State Buckeyes) that looks to be promising. It covers a wide-array of technologies with a Microsoft focus and some other things pertinent to the IT community. From the site: "This is a local conference by community IT professionals showcasing Microsoft technologies. There will be speakers from MS Gold Certified Partners, MS MVPs, IT authors, community leads, and MS Corp subject matter experts."

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  • What does path finding in internet routing do and how is it different from A*?

    - by alan2here
    Note: If you don't understand this question then feel free to ask clarification in the comments instead of voting down, it might be that this question needs some more work at the moment. I've been directed here from the Stack Excange chat room Root Access because my question didn't fit on Super User. In many aspects path finding algorithms like A star are very similar to internet routing. For example: A node in an A* path finding system can search for a path though edges between other nodes. A router that's part of the internet can search for a route though cables between other routers. In the case of A*, open and closed lists are kept by the system as a whole, sepratly from any individual node as well as each node being able to temporarily store a state involving several numbers. Routers on the internet seem to have remarkable properties, as I understand it: They are very performant. New nodes can be added at any time that use a free address from a finite (not tree like) address space. It's real routing, like A*, there's never any doubling back for example. Similar IP addresses don't have to be geographically nearby. The network reacts quickly to changes to the networks shape, for example if a line is down. Routers share information and it takes time for new IP's to be registered everywhere, but presumably every router doesn't have to store a list of all the addresses each of it's directions leads most directly to. I'm looking for a basic, general, high level description of the algorithms workings from the point of view of an individual router. Does anyone have one? I presume public internet routers don't use A* as the overheads would be to large, and scale to poorly. I also presume there is a single method worldwide because it seems as if must involve a lot of transferring data to update and communicate a reasonable amount of state between neighboring routers. For example, perhaps the amount of data that needs to be stored in each router scales logarithmically with the number of routers that exist worldwide, the detail and reliability of the routing is reduced over increasing distances, there is increasing backtracking involved in parts of the network that are less geographically uniform or maybe each router really does perform an A* style search, temporarily maintaining open and closed lists when a packet arrives.

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  • Replicate a system as is

    - by Sarvesh Lad
    How do i repliacate a system as is. i have installed ubuntu from the minimal iso... i have kept it to minimum now i m using UCK to customise a live cd is there anyway i can replicate my installed system as is? i.e. install apps that i have install and remove apps that i have not installed/removed i tried using synaptics and saving the marking full state way and when i read it when customizing, it doesnt remove the apps that i have removed it just reads installs more apps, it doesnt remove

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  • PHP 5.4 and Hiphop compatibility

    - by boundless08
    I was wondering does anyone know which of the features in php 5.4 are not supported in php hiphop. There's some questions on the hiphop github wiki, such as this one, that very vaguely state HipHop does not currently support all PHP 5.4 features. At the moment I just have to assume, for working purposes, all new features are not compatible as none are specified to work, if anyone has any insight on this that would be great, thanks in advance.

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  • How to automatically resize the Dash when screen dimensions change?

    - by St.W.
    I use a convertible thinkpad (x201t) and magick-rotation to rotate the screen by 90 degrees in tablet mode. Therefore after rotation the screen's width is only 800 points (the ordinary resolution is 1200x800). The Dash does not adapt to this new state and therefore if I click on it, it is oversized and I cannot reach the applications/files/buttons on its side. Is there a way to tell the Dash that it should only ever use a width of 800 pixels, or any other solution to automatically adapt its size when rotating?

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  • Software Agent construction guidelines

    - by lsoto
    I'm currently studying a Master in Computer Science and I am interested in working with Software Agents and C#. I have found so much information regarding theoretical aspects but just a few articles focused on practical programming aspects such as architecture, design or implementation. Could anybody suggest any good source that I could explore? I wouldn't like to "reinvent the wheel" but to contribute with something better to the current state of the art.

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  • Midsize Indepth Newsletter – Simplify And Modernize Your Business With Cloud Solutions

    - by Roxana Babiciu
    Read the Oracle Midsize InDepth Newsletter for the latest Dynamic Market Report on real-world adoption of cloud applications at midsize organizations. Hear from Talent Management expert and evangelist Pamela Stroko on the current state of employee engagement. Find out how midsize companies adopt Oracle WebLogic Server on Oracle Database Appliance. Plus view new research reports, videos, success stories and the latest midsize news.

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  • Your Transaction is in Jeopardy -- and You Can't Even Know It!

    - by Adam Machanic
    If you're reading this, please take one minute out of your day and vote for the following Connect item : https://connect.microsoft.com/SQLServer/feedback/details/444030/sys-dm-tran-active-transactions-transaction-state-not-updated-when-an-attention-event-occurs If you're really interested, take three minutes: run the steps to reproduce the issue, and then check the box that says that you were able to reproduce the issue. Why? Imagine that ten hours ago you started a big transaction. You're sitting...(read more)

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  • POST and PUT requests – is it just the convention?

    - by bckpwrld
    I've read quite a few articles on the difference between POST and PUT and in when the two should be used. But there are still few things confusing me ( hopefully questions will make some sense ): 1) We should use PUT to create resources when we want clients to specify the URI of the newly created resources and we should use POST to create resources when we let service generate the URI of the newly created resources. a) Is it just by convention that POST create request doesn't contain an URI of the newly created resource or POST create request actually can't contain the URI of the newly created resource? b) PUT has idempotent semantics and thus can be safely used for absolute updates ( ie we send entire state of the resource to the server ), but not also for relative updates ( ie we send just changes to the resource state ), since that would violate its semantics. But I assume it's still possible for PUT to send relative updates to the server, it's just that in that case the PUT update won't be idempotent? 2) I've read somewhere that we should "use POST to append a resource to a collection identified by a service-generated URI". a) What exactly does that mean? That if URIs for the resources were generated by a server ( thus the resources were created via POST ), then ALL subsequent resources should also be created via POST? Thus, in such situation no resource should be created via PUT? b) If my assumption under a) is correct, could you elaborate why we shouldn't create some resources via POST and some via PUT ( assuming server already contains a collection of resources created via POST )? REPLY: 1) Please correct me if I'm wrong, but from your post and from the link you've posted, it seems: a) The Request-URI in POST is interpreted by server as the URI of the service. Thus, it could just as easily be interpreted as an URI of a newly created resource, if server code was written to recognize Request-URI as such b) Similarly, PUT is able to send relative updates, it's just that service code is usually written such that it will complain if PUT updates are relative. 2) Usually, create has fallen into the POST camp, because of the idea of "appending to a collection." It's become the way to append a resource to a list of resources. I don't quite understand the reasoning behind the idea of "appending to a collection" and why this idea prefers POST for create. Namely, if we create 10 resources via PUT, then server will contain a collection of 10 resources and if we then create another resource, then server will append this resource to that collection ( which will now contain 11 resources )?! Uh, this is kinda confusing thank you

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  • Understanding the Microsoft Permissive License

    - by cable729
    I want to use certain parts of the Game State Management Example in a game I'm making, but I'm not sure how to do this legally. It says in the license that I'm supposed to include a copy of the license with it. So if I make a Visual Studio Solution, I just add the license.txt to the solution? Also, if I use a class and change it, do I have to keep the license info at the top or add that I changed it or what?

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  • Your Transaction is in Jeopardy -- and You Can't Even Know It!

    - by Adam Machanic
    If you're reading this, please take one minute out of your day and vote for the following Connect item : https://connect.microsoft.com/SQLServer/feedback/details/444030/sys-dm-tran-active-transactions-transaction-state-not-updated-when-an-attention-event-occurs If you're really interested, take three minutes: run the steps to reproduce the issue, and then check the box that says that you were able to reproduce the issue. Why? Imagine that ten hours ago you started a big transaction. You're sitting...(read more)

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  • Cannot install "ATI/AMD proprietary FGLRX graphics driver" (SystemError)

    - by Fisherman John
    I have just installed a fresh copy of 12.04.1 64bit. I formatted my PC completely and enabled updates during the installation. After the installation was complete, I went on updating my software. However, when I wanted to install the additional drivers using the Additional Drivers tool (namely "ATI/AMD proprietary FGLRX graphics driver"), it gave me this error: SystemError: E:Unable to correct problems, you have held broken packages. The same error shows up if I try installing the post-release updates driver. Installing the drivers from the terminal results in this output: XXXXXX:~$ sudo apt-get install fglrx [sudo] password for XXXXX: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: fglrx : Depends: lib32gcc1 but it is not going to be installed Depends: libc6-i386 but it is not going to be installed E: Unable to correct problems, you have held broken packages." I get this using "sudo apt-get update": http://pastebin.com/AWAtDXjY But "sudo apt-get install fglrx" still get me this error: http://pastebin.com/RYM55bVN & "sudo apt-get -f install fglrx" gives me this error: http://pastebin.com/xxekajvP Any help would be greatly appreciated. (Please note that I'm new to Linux, coming directly from Windows. I have tried Ubuntu twice or so before, but it was not for a long period of time. The drivers got installed smoothly the few times I've tried Ubuntu, but post-release updates never worked for me.) [I am going to work now, so I can only answer from my phone. Can't really test any new solutions you may give me until ~10 hours from now on. Maybe more.] @stonedsquirrel When I try to run that command, I get this error: "XXXXXX:~$ sudo apt-get install fglrx [sudo] password for XXXXX: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: fglrx : Depends: lib32gcc1 but it is not going to be installed Depends: libc6-i386 but it is not going to be installed E: Unable to correct problems, you have held broken packages." ie. I get the same error. ( I am Fisherman John, dunno how to login & thereby respond to your comment again _ )

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  • Extend OER to enable deletion of unsubmitted assets

    - by Bob Webster
    This post provides a small extension to OER 11g that allows users without full Registrar permissions to delete their own unsubmitted assets. When the extension is installed in OER, a delete button conditionally appears on the Asset Details page of the OER Web App. The button is only visible if the selected Asset is in the 'Unsubmitted' state and the asset was created by the current user. Read the full post here 

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  • Is it appropriate to try to control the order of finalization?

    - by Strilanc
    I'm writing a class which is roughly analogous to a CancellationToken, except it has a third state for "never going to be cancelled". At the moment I'm trying to decide what to do if the 'source' of the token is garbage collected without ever being set. It seems that, intuitively, the source should transition the associated token to the 'never cancelled' state when it is about to be collected. However, this could trigger callbacks who were only kept alive by their linkage from the token. That means what those callbacks reference might now in the process of finalization. Calling them would be bad. In order to "fix" this, I wrote this class: public sealed class GCRoot { private static readonly GCRoot MainRoot = new GCRoot(); private GCRoot _next; private GCRoot _prev; private object _value; private GCRoot() { this._next = this._prev = this; } private GCRoot(GCRoot prev, object value) { this._value = value; this._prev = prev; this._next = prev._next; _prev._next = this; _next._prev = this; } public static GCRoot Root(object value) { return new GCRoot(MainRoot, value); } public void Unroot() { lock (MainRoot) { _next._prev = _prev; _prev._next = _next; this._next = this._prev = this; } } } intending to use it like this: Source() { ... _root = GCRoot.Root(callbacks); } void TransitionToNeverCancelled() { _root.Unlink(); ... } ~Source() { TransitionToNeverCancelled(); } but now I'm troubled. This seems to open the possibility for memory leaks, without actually fixing all cases of sources in limbo. Like, if a source is closed over in one of its own callbacks, then it is rooted by the callback root and so can never be collected. Presumably I should just let my sources be collected without a peep. Or maybe not? Is it ever appropriate to try to control the order of finalization, or is it a giant warning sign?

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