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  • Which Cortex-M3 interrupts can I use for general purpose work?

    - by Captain NedD
    I'd have some code that needs to be run as the result of a particular interrupt going off. I don't want to execute it in the context of the interrupt itself but I also don't want it to execute in thread mode. I would like to run it at a priority that's lower than the high level interrupt that precipitated its running but also a priority that higher than thread level (and some other interrupts as well). I think I need to use one of the other interrupt handlers. Which ones are the best to use and what the best way to invoke them? At the moment I'm planning on just using the interrupt handlers for some peripherals that I'm not using and invoking them by setting bits directly through the NVIC but I was hoping there's a better, more official way. Thanks,

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  • What is the general feeling about reflection extensions in std::type_info?

    - by Evan Teran
    I've noticed that reflection is one feature that developers from other languages find very lacking in c++. For certain applications I can really see why! It is so much easier to write things like an IDE's auto-complete if you had reflection. And certainly serialization APIs would be a world easier if we had it. On the other side, one of the main tenets of c++ is don't pay for what you don't use. Which makes complete sense. That's something I love about c++. But it occurred to me there could be a compromise. Why don't compilers add extensions to the std::type_info structure? There would be no runtime overhead. The binary could end up being larger, but this could be a simple compiler switch to enable/disable and to be honest, if you are really concerned about the space savings, you'll likely disable exceptions and RTTI anyway. Some people cite issues with templates, but the compiler happily generates std::type_info structures for template types already. I can imagine a g++ switch like -fenable-typeinfo-reflection which could become very popular (and mainstream libs like boost/Qt/etc could easily have a check to generate code which uses it if there, in which case the end user would benefit with no more cost than flipping a switch). I don't find this unreasonable since large portable libraries like this already depend on compiler extensions. So why isn't this more common? I imagine that I'm missing something, what are the technical issues with this?

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  • how to clone the drag-event using jquery and jquery-ui.

    - by zjm1126
    i want to create a new '.b' div appendTo document.body, and it can dragable like its father, but i can not clone the drag event, how to do this, thanks this is my code : <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta name="viewport" content="width=device-width, user-scalable=no"> </head> <body> <style type="text/css" media="screen"> </style> <div id="map_canvas" style="width: 500px; height: 300px;background:blue;"></div> <div class=b style="width: 20px; height: 20px;background:red;position:absolute;left:700px;top:200px;"></div> <script src="jquery-1.4.2.js" type="text/javascript"></script> <script src="jquery-ui-1.8rc3.custom.min.js" type="text/javascript"></script> <script type="text/javascript" charset="utf-8"> $(".b").draggable({ start: function(event,ui) { //console.log(ui) //$(ui.helper).clone(true).appendTo($(document.body)) $(this).clone(true).appendTo($(document.body))//draggable is not be cloned, } }); $("#map_canvas").droppable({ drop: function(event,ui) { //console.log(ui.offset.left+' '+ui.offset.top) ui.draggable.remove(); } }); </script> </body> </html>

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  • Searches (and general querying) with HBase and/or Cassandra (best practices?)

    - by alexeypro
    I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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  • What's the best general programming book to review basic development concepts?

    - by Charles S.
    I'm looking for for a programming book that reviews basic concepts like implementing linked lists, stacks, queues, hash tables, tree traversals, search algorithms, etc. etc. Basically, I'm looking for a review of everything I learned in college but have forgotten. I prefer something written in the last few years that includes at least a decent amount of code in object-oriented languages. This is to study for job interview questions but I already have the "solving interview questions" books. I'm looking for something with a little more depth and explanation. Any good recommendations?

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  • Can I use POSIX signals in my Perl program to create event-driven programming?

    - by Shiftbit
    Is there any POSIX signals that I could utilize in my Perl program to create event-driven programming? Currently, I have multi-process program that is able to cross communicate but my parent thread is only able to listen to listen at one child at a time. foreach (@proc) { sysread(${$_}{'read'}, my $line, 100); #problem here chomp($line); print "Parent hears: $line\n"; } The problem is that the parent sits in a continual wait state until it receives it a signal from the first child before it can continue on. I am relying on 'pipe' for my intercommunication. My current solution is very similar to: http://stackoverflow.com/questions/2558098/how-can-i-use-pipe-to-facilitate-interprocess-communication-in-perl If possible I would like to rely on a $SIG{...} event or any non-CPAN solution. Update: As Jonathan Leffler mentioned, kill can be used to send a signal: kill USR1 = $$; # send myself a SIGUSR1 My solution will be to send a USR1 signal to my child process. This event tells the parent to listen to the particular child. child: kill USR1 => $parentPID if($customEvent); syswrite($parentPipe, $msg, $buffer); #select $parentPipe; print $parentPipe $msg; parent: $SIG{USR1} = { #get child pid? sysread($array[$pid]{'childPipe'}, $msg, $buffer); }; But how do I get my the source/child pid that signaled the parent? Have the child Identify itself in its message. What happens if two children signal USR1 at the same time?

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  • How Can I Create Reports in a Custom C#.NET Windows Application? - General Question

    - by user311509
    Assume i have a custom Windows application written in C#. This application has only the following functionalists, add, edit, delete and view. For example, a user can add a sale, change sales record, delete a sale record or view the whole sales record. I need to add some reporting functionalists e.g. i want a user to print the sales of a certain customer from 2008 to 2009 into pdf, what all products a certain customer has purchased from us and so on. I will only include the basic common report requests that are usually needed in the office. Any other kind of reports that are requested inconsistently, i would do it manually from my side at the back end and send the results manually to the requester. What i would do is: If a user wants more info of a certain customer, a special window box appears for that customer. This window box will have different controls that allows user to request more info such as, print customer purchases from ..... to ..... (user chooses the dates) and user will view results in pdf or so. Of course, at the back scene i will write an appropriate SQL Query with parameters that meets a certain function. Is this how it should be done? I have heard about SQL Reporting, i don't know anything about it yet. I will check it out. Anyhow, your suggestions won't harm. I'm still a student, so i don't have practical experience yet. I hope my question is clear enough. Thank you.

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  • Is using a FSM a good design for general text parsing?

    - by eSKay
    I am reading a file that is filled with hex numbers. I have to identify a particular pattern, say "aaad" (without quotes) from it. Every time I see the pattern, I generate some data to some other file. This would be a very common case in designing programs - parsing and looking for a particular pattern. I have designed it as a Finite State Machine and structured structured it in C using switch-case to change states. This was the first implementation that occured to me. DESIGN: Are there some better designs possible? IMPLEMENTATION: Do you see some problems with using a switch case as I mentioned?

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  • Is the Keychain suitable for storing general data, such as strings?

    - by cannyboy
    The Keychain seems to be used a lot for usernames and passwords, but is it a good idea to use it for other sensitive stuff (bank details, ID numbers etc), but with no password? What kind of encryption does the keychain use? The scenario I'm concerned about is a thief acquiring an iPhone (which is screen-locked) and being able to access the file system to get this info. Also, would using the Keychain involve export restrictions due to the use of encryption?

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  • What is the proper way to assign a general udf to application.cfc?

    - by Tom Hubbard
    I simply want to define a function in application.cfc and expose it application wide to all requests. Preferably the "assignment" would only happen on application startup. Is the preferred method to do something along the lines of this: <CFCOMPONENT OUTPUT="FALSE"> <CFSET this.name = "Website"> <CFSET this.clientManagement = true> <CFSET this.SessionManagement = true> <CFFUNCTION NAME="GetProperty" OUTPUT="False"> <CFARGUMENT NAME="Property"> <CFRETURN this.Props[Property]> </CFFUNCTION> <CFFUNCTION NAME="OnApplicationStart" OUTPUT="FALSE"> <CFSET Application.GetProperty = GetProperty> . . . or is there something better?

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  • How to get a JTextField event that started a pop up menu in Java ?

    - by Frank
    I have a JTextField that represents a day, such as "Sunday", when I left mouse click on it, it changes background color, when I right mouse click on it, a pop up menu comes up, after I click on a menu item, such as "1st of month", it gets the value, closes the menu and then change the bgcolor, my code looks like this : JTextField dayHeading=new JTextField("Su"); ...... final JPopupMenu Pmenu; JMenuItem menuItem; Pmenu=new JPopupMenu(); menuItem=new JMenuItem("1st of month"); Pmenu.add(menuItem); menuItem=new JMenuItem("2nd of month"); Pmenu.add(menuItem); ...... menuItem.addMouseListener(new MouseAdapter() { public void mouseReleased(final MouseEvent e) { System.out.println(((JMenuItem)e.getComponent()).getText()); onHeadingClicked(e); // Error : java.lang.ClassCastException: javax.swing.JMenuItem cannot be cast to javax.swing.JTextField // How to get the orininal JTextField event that started this pop up menu, so I can pass it onto onHeadingClicked() ? } }); ...... dayHeading.setEditable(false); dayHeading.setFocusable(false); dayHeading.addMouseListener(new MouseAdapter() { public void mouseReleased(final MouseEvent evt) { if (SwingUtilities.isLeftMouseButton(evt)) onHeadingClicked(evt); else if (SwingUtilities.isRightMouseButton(evt)) Pmenu.show(evt.getComponent(),evt.getX(),evt.getY()); } }); ...... void onHeadingClicked(final java.awt.event.MouseEvent evt) { final javax.swing.JTextField fld=(javax.swing.JTextField) evt.getSource(); ... } My question is : in the menuItem.addMouseListener section, how to get the orininal JTextField event that started this pop up menu, so I can pass it onto onHeadingClicked() ?

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  • Shader vs Shader Material , papervision specific , general insight welcome.

    - by RadAdam
    hello overflow. I asked this question on the pv3d forum and not a single person could, or cared to answer it. Im relatively new to 3d so i apologize if this is common sense to some. I have a sphere , in which i am applying a CellMaterial to. Looks great. I noticed that in the papervision sdk , there is also a CellShader. Should I be using this in congruence with the CellMaterial ? Should it be one or the other ? Is shader , a deprecated practice to Shader Material ? My initial thoughts were that the shader applies to the whole scene , while materials can be applied uniquely to objects. The documentation seems to show otherwise. What benefit if any could be gained by using both a CellShader and a CellMaterial ? id really love to get some ambient inclusion in there some how.

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  • Does The Clear Method On A Collection Release The Event Subscriptions?

    - by DaveB
    I have a collection private ObservableCollection<Contact> _contacts; In the constructor of my class I create it _contacts = new ObservableCollection<Contact>(); I have methods to add and remove items from my collection. I want to track changes to the entities in my collection which implement the IPropertyChanged interface so I subscribe to their PropertyChanged event. public void AddContact(Contact contact) { ((INotifyPropertyChanged)contact).PropertyChanged += new PropertyChangedEventHandler(Contact_PropertyChanged); _contacts.Add(contact); } public void AddContact(int index, Contact contact) { ((INotifyPropertyChanged)contact).PropertyChanged += new PropertyChangedEventHandler(Contact_PropertyChanged); _contacts.Insert(index, contact); } When I remove an entity from the collection, I unsubscribe from the PropertyChanged event. I am told this is to allow the entity to be garbage collected and not create memory issues. public void RemoveContact(Contact contact) { ((INotifyPropertyChanged)contact).PropertyChanged -= Contact_PropertyChanged; _contacts.Remove(contact); } So, I hope this is all good. Now, I need to clear the collection in one of my methods. My first thought would be to call _contacts.Clear(). Then I got to wondering if this releases those event subscriptions? Would I need to create my own clear method? Something like this: public void ClearContacts() { foreach(Contact contact in _contacts) { this.RemoveContact(contact); } } I am hoping one of the .NET C# experts here could clear this up for me or tell me what I am doing wrong.

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  • How to use data receive event in Socket class?

    - by affan
    I have wrote a simple client that use TcpClient in dotnet to communicate. In order to wait for data messages from server i use a Read() thread that use blocking Read() call on socket. When i receive something i have to generate various events. These event occur in the worker thread and thus you cannot update a UI from it directly. Invoke() can be use but for end developer its difficult as my SDK would be use by users who may not use UI at all or use Presentation Framework. Presentation framework have different way of handling this. Invoke() on our test app as Microstation Addin take a lot of time at the moment. Microstation is single threaded application and call invoke on its thread is not good as it is always busy doing drawing and other stuff message take too long to process. I want my events to generate in same thread as UI so user donot have to go through the Dispatcher or Invoke. Now i want to know how can i be notified by socket when data arrive? Is there a build in callback for that. I like winsock style receive event without use of separate read thread. I also do not want to use window timer to for polling for data. I found IOControlCode.AsyncIO flag in IOControl() function which help says Enable notification for when data is waiting to be received. This value is equal to the Winsock 2 FIOASYNC constant. I could not found any example on how to use it to get notification. If i am write in MFC/Winsock we have to create a window of size(0,0) which was just used for listening for the data receive event or other socket events. But i don't know how to do that in dotnet application.

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  • How can I keep an event from being delivered to the GUI until my code finished running?

    - by Frerich Raabe
    I installed a global mouse hook function like this: mouseEventHook = ::SetWindowsHookEx( WH_MOUSE_LL, mouseEventHookFn, thisModule, 0 ); The hook function looks like this: RESULT CALLBACK mouseEventHookFn( int code, WPARAM wParam, LPARAM lParam ) { if ( code == HC_ACTION ) { PMSLLHOOKSTRUCT mi = (PMSLLHOOKSTRUCT)lParam; // .. do interesting stuff .. } return ::CallNextHookEx( mouseEventHook, code, wParam, lParam ); } Now, my problem is that I cannot control how long the 'do interesting stuff' part takes exactly. In particular, it might take longer than the LowLevelHooksTimeout defined in the Windows registry. This means that, at least on Windows XP, the system no longer delivers mouse events to my hook function. I'd like to avoid this, but at the same time I need the 'do interesting stuff' part to happen before the target GUI receives the event. I attempted to solve this by doing the 'interesting stuff' work in a separate thread so that the mouseEventHookFn above can post a message to the worker thread and then do a return 1; immediately (which ends the hook function but avoids that the event is handed to the GUI). The idea was that the worker thread, when finished, performs the CallNextHookEx call itself. However, this causes a crash inside of CallNextHookEx (in fact, the crash occurs inside an internal function called PhkNextValid. I assume it's not safe to call CallNextHookEx from outside a hook function, is this true? If so, does anybody else know how I can run code (which needs to interact with the GUI thread of an application) before the GUI receives the event and avoid that my hook function blocks too long?

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  • Curious: Could LLVM be used for Infocom z-machine code, and if so how? (in general)

    - by jonhendry2
    Forgive me if this is a silly question, but I'm wondering if/how LLVM could be used to obtain a higher performance Z-Machine VM for interactive fiction. (If it could be used, I'm just looking for some high-level ideas or suggestions, not a detailed solution.) It might seem odd to desire higher performance for a circa-1978 technology, but apparently Z-Machine games produced by the modern Inform 7 IDE can have performance issues due to the huge number of rules that need to be evaluated with each turn. Thanks! FYI: The Z-machine architecture was reverse-engineered by Graham Nelson and is documented at http://www.inform-fiction.org/zmachine/standards/z1point0/overview.html

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  • Using a general class for execution with try/catch/finally?

    - by antirysm
    I find myself having a lot of this in different methods in my code: try { runABunchOfMethods(); } catch (Exception ex) { logger.Log(ex); } What about creating this: public static class Executor { private static ILogger logger; public delegate void ExecuteThis(); static Executor() { // logger = ...GetLoggerFromIoC(); } public static void Execute(ExecuteThis executeThis) { try { executeThis(); } catch (Exception ex) { logger.Log(ex); } } } And just using it like this: private void RunSomething() { Method1(someClassVar); Method2(someOtherClassVar); } ... Executor.Execute(RunSomething); Are there any downsides to this approach? (You could add Executor-methods and delegates when you want a finally and use generics for the type of Exeception you want to catch...)

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  • How do I update the UI during an event using ASP.NET?

    - by Phil Hale
    I'm a bit stuck with a problem. I feel like the solution should be fairly straight forward but I'm completely out of ideas for some reason. Here's the problem. I've got a user control with a couple of buttons. Think of them as 'On' and 'Off'. When either button is clicked an async method is called. If the method is successful an event is fired. Within the event I want to update the enabled property of the two buttons so that only a single button is clickable at any one time. The problem is that any changes I make to the properties are not shown on screen because the postback is already complete. I tried wrapping the buttons in an UpdatePanel but I get an "Update method can only be called on UpdatePanel with ID 'xxxx' before Render' error. I understand why the problem occurs but I can't think of a solution. Help! Ideally what I'd like to do is simply call a method within the event that will update the UI, but I don't know if that's possible.

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  • General approach for posting business logic status messages to UI?

    - by generalt
    Hello all. I have been struggling with this question for awhile now, and I haven't reached a conclusion. I'm not typically a UI programmer, so forgive the noobishness. I'm writing a typical application with a UI layer (WPF) and a business layer. I want to post status messages to the UI from the business layer (perhaps deep within the business layer), but I don't want the business layer to have any knowledge of the UI. Is there a generally accepted pattern for this? I was thinking to have a message queue of some sort to which the business layer posts status messages, and have the view model of the UI subscribe to that queue and intercept messages from the queue and route them to the UI. Is that a good approach? Is there somewhere else I should start? Thank you.

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  • How can I do something when a runloop event is done processing?

    - by quixoto
    I have some processing in my Cocoa app that sometimes ends up calling through a hierarchy of data to do a bunch of work as the result of an event. Each small piece creates and destroys some resources. I don't want those resources around most of the time, but I would like to find a smart way of creating them before all the work and killing them at the end. Short of making those buffers etc available globally from the "parent" or elsewhere, is there a way to know locally in some code when an event loop run has ended? Then I could create them if they're not there, and keep them until the run loop ends, reusing them for any subsequent calls before that time. EDIT: I'm not looking for suggestions on how to restructure my code, which I may do anyways. This issue just brought up the question for me of how to know when the runloop is done. If I were writing in, I dunno, Javascript, I'd use a setTimeout with zero to accomplish end-event cleanup. I suppose an NSTimer with an interval of zero might accomplish this too, but wondering if there's something cleaner. Thanks.

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