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• Windows cmd encoding change causes Python crash.

  - by Alex

  First I chage Windows CMD encoding to utf-8 and run Python interpreter: chcp 65001 python Then I try to print a unicode sting inside it and when i do this Python crashes in a peculiar way (I just get a cmd prompt in the same window). >>> import sys >>> print u'ëèæîð'.encode(sys.stdin.encoding) Any ideas why it happens and how to make it work? UPD: sys.stdin.encoding returns 'cp65001' UPD2: It just came to me that the issue might be connected with the fact that utf-8 uses multi-byte character set (kcwu made a good point on that). I tried running the whole example with 'windows-1250' and got 'ëeaî?'. Windows-1250 uses single-character set so it worked for those characters it understands. However I still have no idea how to make 'utf-8' work here. UPD3: Oh, I found out it is a known Python bug. I guess what happens is that Python copies the cmd encoding as 'cp65001 to sys.stdin.encoding and tries to apply it to all the input. Since it fails to understand 'cp65001' it crushes on any input that contains non-ascii characters.

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• Monotouch threads, GC, WCF

  - by cvista

  Hi This is a question about best practices i guess but it applies directly to my current MT project. I'm using WCF services to communicate with the server. To do this i do the following: services.MethodToCall(params); and the asynch: services.OnMethodToCallCompleted += delegate{ //do stuff and ting }; This can lead to issues if you're not careful in that variables defined within the scope of the asynch callback can sometimes be cleaned up by the gc and this can cause crashes. So - I am making it a practice to declare these outside of the scope of the callback unless I am 100% sure they are not needed. Now - when doing stuff and ting implies changing the ui - i wrap it all in an InvokeOnMainThread call. I guess wrapping everything in this would slow the main thread down and rubbish the point of having multi threads. Even though I'm being careful about all this i am still getting crashes and I have no idea why! I am certain it has something to do with threads, scope and all that. Now - the only thing I can think of outside of updating the UI that may need to happen inside of InvokeOnMainThread is that I have a singleton 'Database' class. This is based on the version 5 code from this thread http://www.yoda.arachsys.com/csharp/singleton.html So now if the service method returns data that needs to be added/updated to the Database class -I also wrap this inside an InvokeOnMainThread call. Still getting random crashes. So... My question is this: I am new to thick client dev - I'm coming from a web dev perspective where we don't need to worry about threads so much :) Aside from what I have mentioned -are there any other things I should be aware of? Is the above stuff correct? Or am i miss-understanding something? Cheers w://

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• How to find Tomcat's PID and kill it in python?

  - by 4herpsand7derpsago

  Normally, one shuts down Apache Tomcat by running its shutdown.sh script (or batch file). In some cases, such as when Tomcat's web container is hosting a web app that does some crazy things with multi-threading, running shutdown.sh gracefully shuts down some parts of Tomcat (as I can see more available memory returning to the system), but the Tomcat process keeps running. I'm trying to write a simple Python script that: Calls shutdown.sh Runs ps -aef | grep tomcat to find any process with Tomcat referenced If applicable, kills the process with kill -9 <PID> Here's what I've got so far (as a prototype - I'm brand new to Python BTW): #!/usr/bin/python # Imports import sys import subprocess # Load from imported module. if __init__ == "__main__": main() # Main entry point. def main(): # Shutdown Tomcat shutdownCmd = "sh ${TOMCAT_HOME}/bin/shutdown.sh" subprocess.call([shutdownCmd], shell=true) # Check for PID grepCmd = "ps -aef | grep tomcat" grepResults = subprocess.call([grepCmd], shell=true) if(grepResult.length > 1): # Get PID and kill it. pid = ??? killPidCmd = "kill -9 $pid" subprocess.call([killPidCmd], shell=true) # Exit. sys.exit() I'm struggling with the middle part - with obtaining the grep results, checking to see if their size is greater than 1 (since grep always returns a reference to itself, at least 1 result will always be returned, methinks), and then parsing that returned PID and passing it into the killPidCmd. Thanks in advance!

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• Python C API from C++ app - know when to lock

  - by Alex

  Hi Everyone, I am trying to write a C++ class that calls Python methods of a class that does some I/O operations (file, stdout) at once. The problem I have ran into is that my class is called from different threads: sometimes main thread, sometimes different others. Obviously I tried to apply the approach for Python calls in multi-threaded native applications. Basically everything starts from PyEval_AcquireLock and PyEval_ReleaseLock or just global locks. According to the documentation here when a thread is already locked a deadlock ensues. When my class is called from the main thread or other one that blocks Python execution I have a deadlock. Python Cfunc1() - C++ func that creates threads internally which lead to calls in "my class", It stuck on PyEval_AcquireLock, obviously the Python is already locked, i.e. waiting for C++ Cfunc1 call to complete... It completes fine if I omit those locks. Also it completes fine when Python interpreter is ready for the next user command, i.e. when thread is calling funcs in the background - not inside of a native call I am looking for a workaround. I need to distinguish whether or not the global lock is allowed, i.e. Python is not locked and ready to receive the next command... I tried PyGIL_Ensure, unfortunately I see hang. Any known API or solution for this ? (Python 2.4)

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• fullCalendar: Implementing a custom event fetcher using event as function

  - by Nick-ACNB

  If I specify a json feed, the events are re-fetched everytime and the fetching time shows the item appearing which causes a delay which is undesirable (at least after initial fetch was done). I am using the latest version from gitHub 1.4.6. The lazyFetching property seems to only work when you change views and you previously fetched for example a month and are drilling down to week/day which is unusable since I only use agendaDay. Here is what I am trying to achieve: $("#calendar").fullCalendar({ events: function(start, end, callback) { $.getJSON( "/GetEvents", { start: start.valueOf() }, function(data, textStatus) { $.each(data, function(i, event) { //Goal here is to only add items that aren't already rendered. if ($("#calendar") .fullCalendar('clientEvents', event.id)=="") $("#calendar").fullCalendar('renderEvent', event, true); }); } ); }); The goal is to use the sticky property in the renderEvent method so that on-screen they aren't re-rendered if they we're previously fetched. I omitted a part where I manually delete those that we're deleted and modify those that we're updated since I am in multi-user settings but you get the point. My issue is that they are fetched once and added. But once I change day and come back, they don't render even if I used sticky... has anyone gotten this error or did I code anything wrong? Also, is this a wrong way to go? I will consider any input. :) Thank you very much.

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• Returning large collections from WCF Serivce

  - by Nate Bross

  I'm trying to determine the best approach for building a WCF Service, and the area I'm struggling with most is returning lists of objects. The built-in maxMessageSize of 64k seems pretty high, and I really don't want to bump it up (quick googling finds 100s of places bumping the maxMessageSize up to multi-gigabyte range which seems foolish). But, when I'm returning a collection of objects (~150 items) I am exceeding the default 64k. I'm almost to the point of returning my own class which inherits IEnumerable and has properties for hasNext, hasPrevious and PageSize so that I can implement paging on the client side -- this seems like alot of code. The other option is to jackup the maxMessageSize and hope for the best, but that feels wrong. All other aspects of my service are working great, its just returning large collectiosn where I'm having issues. For background, there are two types of consumers of this service, UI applications which will be primarly web and/or wpf applications, and data processing applications, .NET console apps, and maybe some other non-UI apps. For the UI applications, I would like to keep them responsive and keep the messageSize low, on the console apps it doesn't matter as much as they are just pulling data down to do processing and push it back up to the service.

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• how to make Regular expression into non-greedy ?

  - by Rueta

  Hi everyone! I have made a Work with JQ. My Work is a string width a special character block begin and end of string. I want take the text in that special characters, i used regular expression for find in string, but how to make JQ find multi result when have two special character or more. My html here; <div id="container"> <div id="textcontainer"> Cu?c chi?n pháp lý gi?a [|co th?|nghi?m|] th? tru?ng [|test2|dây là test l?n 2|] ch?ng khoán [|M?|day la nuoc my|] và ngân hàng d?u tu quy?n l?c nh?t Ph? Wall m?i ch? b?t d?u. </div> </div> and my JQ $(document).ready(function() { var takedata = $("#textcontainer").text(); var test = 'abcd adddb'; var filterdata = takedata.match(/(\[.+\])/); alert(filterdata); //end write js }); my result is: [|co th?|nghi?m|] th? tru?ng [|test2|dây là test l?n 2|] ch?ng khoán [|M?|day la nuoc my|] . but this is'nt the result i want :(. How to get [text] for times 1 and [demo] for times 2 ?. pls help me !. thankyou :)

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• DB2 Driver Connection Hanging in Glassfish Connection Pool

  - by Ant

  We have an intermittent issue around the DB2 used from a Glassfish connection pool. What happens is this: Under situations where the database (DB2 on ZOS) is under stress, our application (which is a multi-threaded application using connections to DB2 via a Glassfish connection pool) stops doing anything. The following are observed: 1) Looking at the server using JConsole, we can see a thread waiting indefinitely in the DB2 driver's getConnection() method. We can also see that it has gained a lock on a Vector within the driver. Several other threads are also calling the getConnection() method in the driver, and are hanging waiting for the lock on the Vector to be released. 2) Looking at the database itself, we can see that there are connections from the Glassfish server open and waiting to be used. It seems that there is some sort of mismatch between the connection pool on Glassfish and the connections actually open to DB2. Has anyone come across this issue before? Or something similar? If you need any more information that I haven't provided, then please let me know!

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• How to accommodate for the iPhone 4 screen resolution?

  - by dontWatchMyProfile

  This is a programming question! Read on before you vote to close! According to Apple, the iPhone 4 has a new and better screen resolution: 3.5-inch (diagonal) widescreen Multi-Touch display 960-by-640-pixel resolution at 326 ppi This little detail affects our apps in a heavy way. Most of the demo apps on the net have one thing in common: They position views in the believe that the screen has a fixed size of 320 x 480 pixels. So what most -if not all- developers do is: They designed everything in such a way, that a touchable area is -for example- 50 x 50 pixels big. Just enough to tap it. Things have been positioned relative to the upper left, to reach a specific position on screen - let's say the center, or somewhere at the bottom. Edit: It seems Apple has integrated an switch that allows to tell if an app is highRes or not. Nice. When we develop high-resolution apps, they probably won't work on older devices. And if they do, they would suffer a lot from 4-times the size of any image, having to scale them down in memory.

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• Class initialization and synchronized class method

  - by nybon

  Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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• How to use multifieldquery and filters in Lucene.net

  - by Khotu Nam

  I want to perform a multi field search on a lucene.net index but filter the results based on one of the fields. Here's what I'm currently doing: To index the fields the definitions are: doc.Add(new Field("id", id.ToString(), Field.Store.YES, Field.Index.UN_TOKENIZED)); doc.Add(new Field("title", title, Field.Store.NO, Field.Index.TOKENIZED)); doc.Add(new Field("summary", summary, Field.Store.NO, Field.Index.TOKENIZED, Field.TermVector.YES)); doc.Add(new Field("description", description, Field.Store.NO, Field.Index.TOKENIZED, Field.TermVector.YES)); doc.Add(new Field("distribution", distribution, Field.Store.NO, Field.Index.UN_TOKENIZED)); When I perform the search I do the following: MultiFieldQueryParser parser = new MultiFieldQueryParser(new string[]{"title", "summary", "description"}, analyzer); parser.SetDefaultOperator(QueryParser.Operator.AND); Query query = parser.Parse(text); BooleanQuery bq = new BooleanQuery(); TermQuery tq = new TermQuery(new Term("distribution", distribution)); bq.Add(tq, BooleanClause.Occur.MUST); Filter filter = new QueryFilter(bq); Hits hits = searcher.Search(query, filter); However, the result is always 0 hits. What am I doing wrong?

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• How to store data in mysql, to get the fastest performance?

  - by Oden

  Hey, I'm thinking about it, witch of the following two query types would give me the fastest performance for a user messaging module inside my site: The first one i thought about is a multi table setup, witch has a connection table, and a main table. The connection table holds the connection between accounts, and the messaging table. In this case a query would look like following, to get some data of the author, and the messages he has sent: SELECT m.*, a.username FROM messages AS m LEFT JOIN connection_table ON (message_id = m.id) LEFT JOIN accounts AS a ON (account_id = a.id) WHERE m.id = '32341' Inserting into it is a little bit more "complicated". My other idea, and in my thought the better solution of this problem is that i store the data i would use in a connection table in the same table where is store the data of the mail. Sounds like i would get lots of duplicated entries, but no, because i have a field witch has text type and holds user ids like this: *24*32*249* If I want to query them, i use the mysql LIKE method. Deleting is an other problem, but for this i have one more field where i store who has deleted the post. Sad about that i don't know how to join this. So what would you recommend? Are there other ways?

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• MouseMotion Sensor Method Call

  - by user321894

  I have a soon-to-be due assignment due in computer science. I have encountered a problem, for which no matter how long I study the API's of the class and superclasses, I can not figure out. Suppose I wish to design a sort of "Breakout game" where the mouse motion controls the motion of a block that is used to bounce a ball, which then destroys multi colored bricks. How do you specifically make the block "listen" to the mouse? The below code is what I have attempted to achieve the desired results. /** Breakout Program*/ public class Breakout extends GraphicsProgram implements MouseMotionListener { ... /** The Paddle Itself */ private GRect paddle = new GRect(0, HEIGHT-PADDLEBOTTOM_OFFSET, PADDLEWIDTH, PADDLEHEIGHT); ... /** Run the Breakout program. */ public void run() { paddle.setFillColor(Color.BLACK); paddle.setFilled(true); add(paddle); paddle.addMouseListener(this); ... } /** Move the horizontal middle of the paddle to the x-coordinate of the mouse position - * -but keep the paddle completely on the board. */ public void mouseMoved(MouseEvent e) { GPoint p= new GPoint(e.getPoint()); double x = p.getX(); paddle.setLocation(x, HEIGHT-PADDLEBOTTOM_OFFSET); } } Any clarification on why/what I am doing incorrectly would be helpful, thanks.

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• Help me reduce code repetition in a simple jQuery function

  - by user339876

  I have built a carousel using the jQuery cycle plugin. I have 4 links that jump to relevent slides. Right now I have a chunk of code for each link. I am trying to create a single multi-purpose function. $('#features-slide0').click(function() { $('#features-slides').cycle(0); return false; }); $('#features-slide1').click(function() { $('#features-slides').cycle(1); return false; }); $('#features-slide2').click(function() { $('#features-slides').cycle(2); return false; }); $('#features-slide3').click(function() { $('#features-slides').cycle(3); return false; }); I have a rel value on each link that carries the number of the slide. How can I use that to create a single block of code that takes care of the link jump?

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• Problem when get pageContent of URL in java ?

  - by tiendv

  Hi all ! i have a code for get pagecontent from a URL here is code ! import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URL; import java.net.URLConnection; public class GetPageFromURLAction extends Thread { public String stringPageContent; public String targerURL; public String getPageContent(String targetURL) throws IOException { String returnString=""; URL urlString = new URL(targetURL); URLConnection openConnection = urlString.openConnection(); String temp; BufferedReader in = new BufferedReader(new InputStreamReader(openConnection.getInputStream())); while ((temp = in.readLine()) != null) { returnString += temp + "\n"; } in.close(); // String nohtml = sb.toString().replaceAll("\\<.*?>",""); return returnString; } public String getStringPageContent() { return stringPageContent; } public void setStringPageContent(String stringPageContent) { this.stringPageContent = stringPageContent; } public String getTargerURL() { return targerURL; } public void setTargerURL(String targerURL) { this.targerURL = targerURL; } @Override public void run() { try { this.stringPageContent=this.getPageContent(targerURL); } catch (IOException e) { e.printStackTrace(); } } } The problem is : 1 Some time i receive a error lik 405 ,or 403 HTTP error ... and result string is null . To repair i check permission to connect URL but it usualy return null URLConnection openConnection = urlString.openConnection(); openConnection.getPermission( ) is mean that i don't have permission to acess link ? To get resultString without HTML Tag ? i do like that String nohtml = sb.toString().replaceAll("\<.*?",""); Para sb is Stringbulder , but it can't remove all HTML Tab in string return ? I use thread here because i must get page alot of url , so how can i cread a multi thread to impro speed of program ! Thanks

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• Java try finally variations

  - by Petr Gladkikh

  This question nags me for a while but I did not found complete answer to it yet (e.g. this one is for C# http://stackoverflow.com/questions/463029/initializing-disposable-resources-outside-or-inside-try-finally). Consider two following Java code fragments: Closeable in = new FileInputStream("data.txt"); try { doSomething(in); } finally { in.close(); } and second variation Closeable in = null; try { in = new FileInputStream("data.txt"); doSomething(in); } finally { if (null != in) in.close(); } The part that worries me is that the thread might be somewhat interrupted between the moment resource is acquired (e.g. file is opened) but resulting value is not assigned to respective local variable. Is there any other scenarios the thread might be interrupted in the point above other than: InterruptedException (e.g. via Thread#interrupt()) or OutOfMemoryError exception is thrown JVM exits (e.g. via kill, System.exit()) Hardware fail (or bug in JVM for complete list :) I have read that second approach is somewhat more "idiomatic" but IMO in the scenario above there's no difference and in all other scenarios they are equal. So the question: What are the differences between the two? Which should I prefer if I do concerned about freeing resources (especially in heavily multi-threading applications)? Why? I would appreciate if anyone points me to parts of Java/JVM specs that support the answers.

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• SWT Drag and Drop support for Text widget

  - by bryantsai

  I've written an application recently using SWT. In one of its dialog box, I have a few widgets, one of which is Text, which is designed to support DND with other widgets. I've first added DND support for the 2 Tree widgets on the same dialog box (both drag source and drop target). Before I added DND support for that Text widget, I noticed that on Linux platform (gtk), SWT Text widget automatically get drag and drop support. That is, I can already drag from the other Tree widgets and drop on this Text (at any position to inserted there), as well as selecting and dragging any text from this Text to other Tree or Text widget. However, this is only working on Linux platform but not on Windows. The same program, if running on Windows, will not have any DND support for that Text widget (Tree widgets of course have DND support since I specifically write for them). So here's what I want to achieve on Windows as well: drop text at any position in Text widget. before dropping and while hovering, able to see the caret position clearly where the intended position to drop. caret position should move along with the mouse cursor. support multi-line in Text widget SOLUTION: DropTarget target = new DropTarget(sytledText, DND.DROP_MOVE | DND.DROP_COPY); target.setTransfer(new Transfer[] { TextTransfer.getInstance() }); target.addDropListener(new StyleTextDropTargetEffect(sytledText)); Use StyledText instead of Text widget Use StyledTextDropTargetEffect (or extend it) and add it as dr op listener

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• Winsock WSAAsyncSelect sending without an infinite buffer

  - by Xexr

  Hi, This is more of a design question than a specific code question, I'm sure I am missing the obvious, I just need another set of eyes. I am writing a multi-client server based on WSAAsyncSelect, each connection is made into an object of a connection class I have written which contains associated settings and buffers etc. My question concerns FD_WRITE, I understand how it operates: One FD_WRITE is sent immediately after a connection is established. Thereafter, you should send until WSAEWOULDBLOCK is received at which point you store what is left to send in a buffer, and wait to be told that it is ok to send again. This is where I have a problem, how large do I make this holding buffer within each connections object? The amount of time until a new FD_WRITE is received is unknown, I could be attempting to send a lot of stuff during this period, all the time adding to my outgoing buffer. If I make the buffer dynamic, memory usage could spiral out of control if for whatever reason, I am unable to send() and reduce the buffer. So my question is how do you generally handle this situation? Note I am not talking about the network buffer itself which winsock uses, but one of my own creation used to "queue" up sends. Hope I explained that well enough, thanks all!

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• ASP MVC - Routing Required?

  - by evo_9

  I've been reading up on MVC2 which came in VS2010 and it sounds pretty interesting. I'm actually in the middle of a large multi-tenant application project, and have just started coding the UI. I'm considering changing to MVC as I'm not that far along at this point. I have some questions about the Routing capabilities, namely are they required to use MVC or can I more or less ignore Routing? Or do I have to setup a default routing record that will make things work like standard ASPX (as far as routing alone is concerned)? The reason why I don't want to use Routing is because I've already defined a custom URL 'rewrite' mechanism of my own (which fires on session_start). In addition, I'm using jquery and opens-standards for the entire UI, and MVC's aspx overhead-free approach seems like a better fit based on how I've already started to build the application (I am not using viewstate at all, for example). I guess my big concern is whether the routing can be ignored, of if I will have to re-implement my custom URL rewriting to work with MVC, and if that's the case, how would I do that? As a new Routing routine, or stick with the session_start (if that's even possible?). Lastly, I don't want to use anything even remotely 'intelligent/readable' for the url - for a site like StackOverflow, the readability of the URL is a positive, but the opposite is true if it's not a public website like this one. In fact, it would seem to me that the more friendly MVC routing URL (which indirectly show method names) could pose a security risk on a private, non-public website app like I'm developing. For all these reasons I would love to use the lightweight aspects of MVC but skip the Routing entirely - is this possible?

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• How do I get jQuery's Uploadify plugin to work with ASP.NET MVC?

  - by KingNestor

  I'm in the process of trying to get the jQuery plugin, Uploadify, to work with ASP.NET MVC. I've got the plugin showing up fine: With the following javascript snippet: <script type="text/javascript"> $(document).ready(function() { $('#fileUpload').fileUpload({ 'uploader': '/Content/Flash/uploader.swf', 'script': '/Placement/Upload', 'folder': '/uploads', 'multi': 'true', 'buttonText': 'Browse', 'displayData': 'speed', 'simUploadLimit': 2, 'cancelImg': '/Content/Images/cancel.png' }); }); </script> Which seems like all is well in good. If you notice, the "script" attribute is set to my /Placement/Upload, which is my Placement Controller and my Upload Action. The main problem is, I'm having difficulty getting this action to fire to receive the file. I've set a breakpoint on that action and when I select a file to upload, it isn't getting executed. I've tried changing the method signature based off this article: public string Upload(HttpPostedFileBase FileData) { /* * * Do something with the FileData * */ return "Upload OK!"; } But this still doesn't fire. Can anyone help me write and get the Upload controller action's signature correctly so it will actually fire? I can then handle dealing with the file data myself. I just need some help getting the method action to fire.

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• Thread-safe data structure design

  - by Inso Reiges

  Hello, I have to design a data structure that is to be used in a multi-threaded environment. The basic API is simple: insert element, remove element, retrieve element, check that element exists. The structure's implementation uses implicit locking to guarantee the atomicity of a single API call. After i implemented this it became apparent, that what i really need is atomicity across several API calls. For example if a caller needs to check the existence of an element before trying to insert it he can't do that atomically even if each single API call is atomic: if(!data_structure.exists(element)) { data_structure.insert(element); } The example is somewhat awkward, but the basic point is that we can't trust the result of "exists" call anymore after we return from atomic context (the generated assembly clearly shows a minor chance of context switch between the two calls). What i currently have in mind to solve this is exposing the lock through the data structure's public API. This way clients will have to explicitly lock things, but at least they won't have to create their own locks. Is there a better commonly-known solution to these kinds of problems? And as long as we're at it, can you advise some good literature on thread-safe design? EDIT: I have a better example. Suppose that element retrieval returns either a reference or a pointer to the stored element and not it's copy. How can a caller be protected to safely use this pointer\reference after the call returns? If you think that not returning copies is a problem, then think about deep copies, i.e. objects that should also copy another objects they point to internally. Thank you.

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• Enumerating pixel formats for adaptors and modes with OpenGL

  - by Robinson

  I'm trying to code an OpenGL path for my 3D engine. The D3D path enumerates all device adaptors, all modes (by mode I mean bit depth, dimensions, available windowed, and refresh rate) for each adaptor and then all pixel formats available for the given mode and adaptor, along side certain useful caps (shader version, filter types, etc.). So, I have broadly got the following protected functions in the class: // Enumerate all back/front buffer combinations. virtual void EnumerateBackFrontBufferCombinations(CComPtr<IDirect3D9>& d3d9); // Enumerate all depth/stencil formats. virtual void EnumerateDepthStencilFormats(CComPtr<IDirect3D9>& d3d9); // Enumerate all multi-sample formats. virtual void EnumerateMultiSampleTypes(CComPtr<IDirect3D9>& d3d9); // Enumerate all device formats, i.e. dynamic, static, render target, etc. virtual void EnumerateMapFormats(CComPtr<IDirect3D9>& d3d9); // Enumerate all capabilities. virtual void EnumerateCapabilities(CComPtr<IDirect3D9>& d3d9); The adaptors are enumerated with EnumDisplayDevices, the modes (resolutions and refresh rates) are enumerated with EnumDisplaySettings, so this can be done for either GL or D3D. The other functions I'm not so sure about with OpenGL. What are the equivalents to the IDirect3D9's CheckDeviceType, CheckDeviceFormat, CheckDeviceMultiSampleType, CheckDepthStencilMatch? I know I can use DescribePixelFormat, given a DC, but you kind-of need to have created the window before you can use a DC with it, but you can't create the window correctly until you know what formats you're going to use. Any tips you can give me? Thanks.

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• Django: DatabaseError column does not exist

  - by Rosarch

  I'm having a problem with Django 1.2.4. Here is a model: class Foo(models.Model): # ... ftw = models.CharField(blank=True) bar = models.ForeignKey(Bar) Right after flushing the database, I use the shell: Python 2.6.6 (r266:84292, Sep 15 2010, 15:52:39) [GCC 4.4.5] on linux2 Type "help", "copyright", "credits" or "license" for more information. (InteractiveConsole) >>> from apps.foo.models import Foo >>> Foo.objects.all() Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 67, in __repr__ data = list(self[:REPR_OUTPUT_SIZE + 1]) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 82, in __len__ self._result_cache.extend(list(self._iter)) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 271, in iterator for row in compiler.results_iter(): File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 677, in results_iter for rows in self.execute_sql(MULTI): File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/compiler.py", line 732, in execute_sql cursor.execute(sql, params) File "/usr/local/lib/python2.6/dist-packages/django/db/backends/util.py", line 15, in execute return self.cursor.execute(sql, params) File "/usr/local/lib/python2.6/dist-packages/django/db/backends/postgresql_psycopg2/base.py", line 44, in execute return self.cursor.execute(query, args) DatabaseError: column foo_foo.bar_id does not exist LINE 1: ...t_omg", "foo_foo"."ftw", "foo_foo... What am I doing wrong here?

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• java singleton instantiation

  - by jurchiks

  I've found three ways of instantiating a Singleton, but I have doubts as to whether any of them is the best there is. I'm using them in a multi-threaded environment and prefer lazy instantiation. Sample 1: private static final ClassName INSTANCE = new ClassName(); public static ClassName getInstance() { return INSTANCE; } Sample 2: private static class SingletonHolder { public static final ClassName INSTANCE = new ClassName(); } public static ClassName getInstance() { return SingletonHolder.INSTANCE; } Sample 3: private static ClassName INSTANCE; public static synchronized ClassName getInstance() { if (INSTANCE == null) INSTANCE = new ClassName(); return INSTANCE; } The project I'm using ATM uses Sample 2 everywhere, but I kind of like Sample 3 more. There is also the Enum version, but I just don't get it. The question here is - in which cases I should/shouldn't use any of these variations? I'm not looking for lengthy explanations though (there's plenty of other topics about that, but they all eventually turn into arguing IMO), I'd like it to be understandable with few words.

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• Interface vs Abstract Class (general OO)

  - by Kave

  Hi, I have had recently two telephone interviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I dont know what it is. From my experience I think the following is true, if i am missing a major point please let me know: Interface: Every single Method declared in an Interface will have to be implemented in the subclass. Only Events, Delegates, Properties (C#) and Methods can exist in a Interface. A class can implement multiple Interfaces. Abstract Class Only Abstract methods have to be implemented by the subclass. An Abstract class can have normal methods with implementations. Abstract class can also have class variables beside Events, Delegates, Properties and Methods. A class can only implement one abstract class only due non-existence of Multi-inheritance in C#. 1) After all that the interviewer came up with the question What if you had an Abstract class with only abstract methods, how would that be different from an interface? I didnt know the answer but I think its the inheritance as mentioned above right? 2) An another interviewer asked me what if you had a Public variable inside the interface, how would that be different than in Abstract Class? I insisted you can't have a public variable inside an interface. I didn't know what he wanted to hear but he wasn't satisfied either. Many Thanks for clarification, Kave See Also: When to use an interface instead of an abstract class and vice versa Interfaces vs. Abstract Classes How do you decide between using an Abstract Class and an Interface?

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