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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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  • 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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  • Word wrap in multiline textbox after 35 characters

    - by Kanavi
    <asp:TextBox CssClass="txt" ID="TextBox1" runat="server" onkeyup="CountChars(this);" Rows="20" Columns="35" TextMode="MultiLine" Wrap="true"> </asp:TextBox> I need to implement word-wrapping in a multi-line textbox. I cannot allow users to write more then 35 chars a line. I am using the following code, which breaks at precisely the specified character on every line, cutting words in half. Can we fix this so that if there's not enough space left for a word on the current line, we move the whole word to the next line? function CountChars(ID) { var IntermediateText = ''; var FinalText = ''; var SubText = ''; var text = document.getElementById(ID.id).value; var lines = text.split("\n"); for (var i = 0; i < lines.length; i++) { IntermediateText = lines[i]; if (IntermediateText.length <= 50) { if (lines.length - 1 == i) FinalText += IntermediateText; else FinalText += IntermediateText + "\n"; } else { while (IntermediateText.length > 50) { SubText = IntermediateText.substring(0, 50); FinalText += SubText + "\n"; IntermediateText = IntermediateText.replace(SubText, ''); } if (IntermediateText != '') { if (lines.length - 1 == i) FinalText += IntermediateText; else FinalText += IntermediateText + "\n"; } } } document.getElementById(ID.id).value = FinalText; $('#' + ID.id).scrollTop($('#' + ID.id)[0].scrollHeight); } Edit - 1 I have to show total max 35 characters in line without specific word break and need to keep margin of two characters from the right. Again, the restriction should be for 35 characters but need space for total 37 (Just for the Visibility issue.)

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  • RavenDB - Can I create/query an index, from an application that doesn't share the CLR objects that were persisted?

    - by Jaz Lalli
    This post goes some way to answering this question (I'll include the answer later), but I was hoping for some further details. We have a number of applications that each need to access/manipulate data from Raven in their own way. Data is only written via the main web application. Other apps include batch-style tasks, reporting etc. In an attempt to keep each of these as de-coupled as possible, they are separate solutions. That being the case, how can I, from the reporting application, create indexes over the existing data, using my locally defined types? The answer from the linked question states As long as the structure of the classes you are deserializing into partially matches the structure of the data, it shouldn't make a difference. The RavenDB server doesn't care at all what classes you use in the client. You certainly could share a dll, or even share a portable dll if you are targeting a different platform. But you are correct that it is not necessary. However, you should be aware of the Raven-Clr-Type metadata value. The RavenDB client sets this when storing the original document. It is consumed back by the client to assist with deserialization, but it is not fully enforced It's the first part of that that I wanted clarification on. Do the object graphs for the docs on the server and types in my application have to match exactly? If the Click document on the server is { "Visit": { "Version": "0", "Domain": "www.mydomain.com", "Page": "/index", "QueryString": "", "IPAddress": "127.0.0.1", "Guid": "10cb6886-cb5c-46f8-94ed-4b0d45a5e9ca", "MetaData": { "Version": "1", "CreatedDate": "2012-11-09T15:11:03.5669038Z", "UpdatedDate": "2012-11-09T15:11:03.5669038Z", "DeletedDate": null } }, "ResultId": "Results/1", "ProductCode": "280", "MetaData": { "Version": "1", "CreatedDate": "2012-11-09T15:14:26.1332596Z", "UpdatedDate": "2012-11-09T15:14:26.1332596Z", "DeletedDate": null } } Is it possible (and if so, how?), to create a Map index from my application, which defines the Click class as follows? class Click { public Guid Guid {get;set;} public int ProductCode {get;set;} public DateTime CreatedDate {get;set;} } Or would my class have to be look like this? (where the custom types are defined as a sub-set of the properties on the document above, with matching property names) class Click { public Visit Visit {get;set;} public int ProductCode {get;set;} public MetaData MetaData {get;set;} } UPDATE Following on from the answer below, here's the code I managed to get working. Index public class Clicks_ByVisitGuidAndProductCode : AbstractIndexCreationTask { public override IndexDefinition CreateIndexDefinition() { return new IndexDefinition { Map = "from click in docs.Clicks select new {Guid = click.Visit.Guid, ProductCode = click.ProductCode, CreatedDate = click.MetaData.CreatedDate}", TransformResults = "results.Select(click => new {Guid = click.Visit.Guid, ProductCode = click.ProductCode, CreatedDate = click.MetaData.CreatedDate})" }; } } Query var query = _documentSession.Query<ReportClick, Clicks_ByVisitGuidAndProductCode>() .Customize(x => x.WaitForNonStaleResultsAsOfNow()) .Where(x => x.CreatedDate >= start.Date && x.CreatedDate < end.Date); where Click is public class Click { public Guid Guid { get; set; } public int ProductCode { get; set; } public DateTime CreatedDate { get; set; } } Many thanks @MattJohnson.

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  • Commenting out portions of code in Scala

    - by akauppi
    I am looking for a C(++) #if 0 -like way of being able to comment out whole pieces of Scala source code, for keeping around experimental or expired code for a while. I tried out a couple of alternatives and would like to hear what you use, and if you have come up with something better? // Simply block-marking N lines by '//' is one way... // <tags> """ anything My editor makes this easy, but it's not really The Thing. It gets easily mixed with actual one-line comments. Then I figured there's native XML support, so: <!-- ... did not work --> Wrapping in XML works, unless you have <tags> within the block: class none { val a= <ignore> ... cannot have //<tags> <here> (not even in end-of-line comments!) </ignore> } The same for multi-line strings seems kind of best, but there's an awful lot of boilerplate (not fashionable in Scala) to please the compiler (less if you're doing this within a class or an object): object none { val ignore= """ This seems like ... <truly> <anything goes> but three "'s of course """ } The 'right' way to do this might be: /*** /* ... works but not properly syntax highlighed in SubEthaEdit (or StackOverflow) */ ***/ ..but that matches the /* and */ only, not i.e. /*** to ***/. This means the comments within the block need to be balanced. And - the current Scala syntax highlighting mode for SubEthaEdit fails miserably on this. As a comparison, Lua has --[==[ matching ]==] and so forth. I think I'm spoilt? So - is there some useful trick I'm overseeing?

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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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  • 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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  • What is an elegant way to set up a leiningen project that requires different dependencies based on the build platform?

    - by Savanni D'Gerinel
    In order to do some multi-platform GUI development, I have just switched from GTK + Clojure (because it looks like the Java bindings for GTK never got ported to Windows) to SWT + Clojure. So far, so good in that I have gotten an uberjar built for Linux. The catch, though, is that I want to build an uberjar for Windows and I am trying to figure out a clean way to manage the project.clj file. At first, I thought I would set the classpath to point to the SWT libraries and then build the uberjar. This would require that I set a classpath to the SWT libraries before running the jar, but I would likely need a launcher script, anyway. However, leiningen seems to ignore the classpath in this instance because it always reports that Currently, project.clj looks like this for me: (defproject alyra.mana-punk/character "1.0.0-SNAPSHOT" :description "FIXME: write" :dependencies [[org.clojure/clojure "1.2.0"] [org.clojure/clojure-contrib "1.2.0"] [org.eclipse/swt-gtk-linux-x86 "3.5.2"]] :main alyra.mana-punk.character.core) The relevant line is the org.eclipse/swt-gtk-linux-x86 line. If I want to make an uberjar for Windows, I have to depend on org.eclipse/swt-win32-win32-x86, and another one for x86-64, and so on and so forth. My current solution is to simply create a separate branch for each build environment with a different project.clj. This seems kinda like using a semi to deliver a single gallon of milk, but I am using bazaar for version control, so branching and repeated integrations are easy. Maybe the better way is to have a project.linux.clj, project.win32.clj, etc, but I do not see any way to tell leiningen which project descriptor to use. What are other (preferably more elegant) ways to set up such an environment?

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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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  • Implementing java FixedTreadPool status listener

    - by InsertNickHere
    Hi there, it's about an application which is supposed to process (VAD, Loudness, Clipping) a lot of soundfiles (e.g. 100k). At this time, I create as many worker threads (callables) as I can put into memory, and then run all with a threadPool.invokeAll(), write results to file system, unload processed files and continue at step 1. Due to the fact it's an app with a GUI, i don't want to user to feel like the app "is not responding" while processing all soundfiles. (which it does at this time cause invokeAll is blocking). Im not sure what is a "good" way to fix this. It shall not be possible for the user to do other things while processing, but I'd like to show a progress bar like "10 of 100000 soundfiles are done". So how do I get there? Do I have to create a "watcher thread", so that every worker hold a callback on it? I'm quite new to multi threading, and don't get the idea of such a mechanisem.. If you need to know: I'm using SWT/JFace. Regards, InsertNickHere

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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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  • What makes deployment successful for some users and unsuccessful for others?

    - by Julien
    I am trying to deploy a Visual C++ application (developed with Microsoft Visual Studio 2008) using a Setup and Deployment Project. After installation, users on some target computers get the following error message after launching the application executable: “This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix the problem.” Another user after installation could run the application properly. I cannot find the root cause of this problem, despite spending several hours on the Visual Studio help files and online forums (most postings date back to 2006). Does anyone at Stack Overflow have a suggestion? Thanks in advance. Additional details appear below. The application uses FLTK 1.1.9 for a GUI library, as well as some Boost 1.39 libraries (regex, lexical_cast, date_time, math). I made sure I am trying to deploy the release version (not the debug version) of the application. The Runtime library in the Code Generation settings is Multi-threaded DLL (/MD). The dependency walker of myapp.exe lists the following DLLs: wsock32.dll, comctl32.dll, kernel32.dll, user32.dll, gdi32.dll, shell32.dll, ole32.dll, mvcp90.dll, msvcr90.dll. In the Setup and Deployment Project, I add the following DLLs to the File System on Target Machine: fltkdlld.dll, and a folder named Microsoft.VC90.CRT with msvcm90.dll, msvcp90.dll, mcvcr90.dll and Microsoft.VC90.CRT.manifest. The installation process on the target computers getting the error message requires having the .Net Framework 3.5 installed first. Any suggestion? Thanks in advance!

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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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  • 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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  • PHP Socket Server vs node.js: Web Chat

    - by Eliasdx
    I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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  • swfupload session problem destroy session

    - by saquib
    Hello Friends, I have a problem with swfupload. I am passing session_id() like this /upload-file.php?s=189477fcfa1ec7f630e70a09e1e84cae but its not maintaining session and destroying my current session (logging me out) here is code in file upload. <?php if(isset($_GET['s'])) { session_id($_GET['s']); session_start(); require_once 'admin/class/user.php'; $u = new User(); //Check for user logged in if($u->islogged() == FALSE) { header("location: index.php"); exit(); code continue ..... } because am not logged in server redirect me to the index.php this is swfupload debugger window output SWF DEBUG: ----- END SWF DEBUG OUTPUT ---- SWF DEBUG: SWF DEBUG: Event: fileDialogStart : Browsing files. Multi Select. Allowed file types: *.jpg SWF DEBUG: Select Handler: Received the files selected from the dialog. Processing the file list... SWF DEBUG: Event: fileQueued : File ID: SWFUpload_0_0 SWF DEBUG: Event: fileDialogComplete : Finished processing selected files. Files selected: 1. Files Queued: 1 SWF DEBUG: StartUpload: First file in queue SWF DEBUG: Event: uploadStart : File ID: SWFUpload_0_0 SWF DEBUG: ReturnUploadStart(): File accepted by startUpload event and readied for upload. Starting upload to /upload-file.php?s='189477fcfa1ec7f630e70a09e1e84cae' for File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress (OPEN): File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress: File ID: SWFUpload_0_0. Bytes: 317793. Total: 317793 SWF DEBUG: Event: uploadError: HTTP ERROR : File ID: SWFUpload_0_0. HTTP Status: 302. SWF DEBUG: Event: uploadComplete : Upload cycle complete. SWF DEBUG: StartUpload: First file in queue SWF DEBUG: StartUpload(): No files found in the queue.

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  • Why is debugging better in an IDE?

    - by Bill Karwin
    I've been a software developer for over twenty years, programming in C, Perl, SQL, Java, PHP, JavaScript, and recently Python. I've never had a problem I could not debug using some careful thought, and well-placed debugging print statements. I respect that many people say that my techniques are primitive, and using a real debugger in an IDE is much better. Yet from my observation, IDE users don't appear to debug faster or more successfully than I can, using my stone knives and bear skins. I'm sincerely open to learning the right tools, I've just never been shown a compelling advantage to using visual debuggers. Moreover, I have never read a tutorial or book that showed how to debug effectively using an IDE, beyond the basics of how to set breakpoints and display the contents of variables. What am I missing? What makes IDE debugging tools so much more effective than thoughtful use of diagnostic print statements? Can you suggest resources (tutorials, books, screencasts) that show the finer techniques of IDE debugging? Sweet answers! Thanks much to everyone for taking the time. Very illuminating. I voted up many, and voted none down. Some notable points: Debuggers can help me do ad hoc inspection or alteration of variables, code, or any other aspect of the runtime environment, whereas manual debugging requires me to stop, edit, and re-execute the application (possibly requiring recompilation). Debuggers can attach to a running process or use a crash dump, whereas with manual debugging, "steps to reproduce" a defect are necessary. Debuggers can display complex data structures, multi-threaded environments, or full runtime stacks easily and in a more readable manner. Debuggers offer many ways to reduce the time and repetitive work to do almost any debugging tasks. Visual debuggers and console debuggers are both useful, and have many features in common. A visual debugger integrated into an IDE also gives you convenient access to smart editing and all the other features of the IDE, in a single integrated development environment (hence the name).

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  • How to detect that the internet connection has got disconnected through a java desktop application?

    - by Yatendra Goel
    I am developing a Java Desktop Application that access internet. It is a multi-threaded application, each thread do the same work (means each thread is an instance of same Thread class). Now, as all the threads need internet connection to be active, there should be some mechanism that detects whether an internet connection is active or not. Q1. How to detect whether the internet connection is active or not? Q2. Where to implement this internet-status-check-mechanism code? Should I start a separate thread for checking internet status regularly and notifies all the threads when the status changes from one state to another? Or should I let each thread check for the internet-status itself? Q3. This issue should be a very common issue as every application accessing an internet should deal with this problem. So how other developers usually deal with this problem? Q4. If you could give me a reference to a good demo application that addresses this issue then it would greatly help me.

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  • Non standard interaction among two tables to avoid very large merge

    - by riko
    Suppose I have two tables A and B. Table A has a multi-level index (a, b) and one column (ts). b determines univocally ts. A = pd.DataFrame( [('a', 'x', 4), ('a', 'y', 6), ('a', 'z', 5), ('b', 'x', 4), ('b', 'z', 5), ('c', 'y', 6)], columns=['a', 'b', 'ts']).set_index(['a', 'b']) AA = A.reset_index() Table B is another one-column (ts) table with non-unique index (a). The ts's are sorted "inside" each group, i.e., B.ix[x] is sorted for each x. Moreover, there is always a value in B.ix[x] that is greater than or equal to the values in A. B = pd.DataFrame( dict(a=list('aaaaabbcccccc'), ts=[1, 2, 4, 5, 7, 7, 8, 1, 2, 4, 5, 8, 9])).set_index('a') The semantics in this is that B contains observations of occurrences of an event of type indicated by the index. I would like to find from B the timestamp of the first occurrence of each event type after the timestamp specified in A for each value of b. In other words, I would like to get a table with the same shape of A, that instead of ts contains the "minimum value occurring after ts" as specified by table B. So, my goal would be: C: ('a', 'x') 4 ('a', 'y') 7 ('a', 'z') 5 ('b', 'x') 7 ('b', 'z') 7 ('c', 'y') 8 I have some working code, but is terribly slow. C = AA.apply(lambda row: ( row[0], row[1], B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))), axis=1).set_index(['a', 'b']) Profiling shows the culprit is obviously B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))). However, standard solutions using merge/join would take too much RAM in the long run. Consider that now I have 1000 a's, assume constant the average number of b's per a (probably 100-200), and consider that the number of observations per a is probably in the order of 300. In production I will have 1000 more a's. 1,000,000 x 200 x 300 = 60,000,000,000 rows may be a bit too much to keep in RAM, especially considering that the data I need is perfectly described by a C like the one I discussed above. How would I improve the performance?

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  • Mamimum page fetch with maximum bandwith

    - by Ehsan
    Hi I want to create an application like a spider I've implement fetching page as the following code in multi-thread application but there is two problem 1) I want to use my maximum bandwidth to send/receive request, how should I config my request to do so (Like Download Accelerator application and the like) cause I heard the normal application will use 66% of the available bandwidth. 2) I don't know what exactly HttpWebRequest.KeepAlive do, but as its name implies I think i can create a connection to a website and without closing the connection sending another request to that web site using existing connection. does it boost performance or Im wrong public PageFetchResult Fetch() { PageFetchResult fetchResult = new PageFetchResult(); try { HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(URLAddress); HttpWebResponse resp = (HttpWebResponse)req.GetResponse(); Uri requestedURI = new Uri(URLAddress); Uri responseURI = resp.ResponseUri; if (Uri.Equals(requestedURI, responseURI)) { string resultHTML = ""; byte[] reqHTML = ResponseAsBytes(resp); if (!string.IsNullOrEmpty(FetchingEncoding)) resultHTML = Encoding.GetEncoding(FetchingEncoding).GetString(reqHTML); else if (!string.IsNullOrEmpty(resp.CharacterSet)) resultHTML = Encoding.GetEncoding(resp.CharacterSet).GetString(reqHTML); req.Abort(); resp.Close(); fetchResult.IsOK = true; fetchResult.ResultHTML = resultHTML; } else { URLAddress = responseURI.AbsoluteUri; relayPageCount++; if (relayPageCount > 5) { fetchResult.IsOK = false; fetchResult.ErrorMessage = "Maximum page redirection occured."; relayPageCount = 0; return fetchResult; } req.Abort(); resp.Close(); return Fetch(); } } catch (Exception ex) { fetchResult.IsOK = false; fetchResult.ErrorMessage = ex.Message; } return fetchResult; }

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  • Getting unhandled exception when DataTemplate is created dynamically using Silverlight 3.0

    - by Bhaskar
    Requirement is to create a reusable multi-select combobox custom control. To accomplish this, I am creating the DataTemplate dynamically through code and set the combobox ItemTemplate. I am able to load the datatemplate dynamically and set the ItemTemplate, but getting unhandled exception (code: 7054) when combobox is selected. Here is the code Class MultiSelCombBox: ComboBox { public override void OnApplyTemplate() { base.OnApplyTemplate(); CreateTemplate(); } void CreateTemplate() { DataTemplate dt = null; if (CreateItemTemplate) { if (string.IsNullOrEmpty(CheckBoxBind)) { dt = XamlReader.Load(@"<DataTemplate xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' x:Name=""DropDownTemplate""><Grid xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' x:Name=""CheckboxGrid""><TextBox xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' x:Name=""test"" xml:space=""preserve"" Text='{Binding " + TextContent + "}'/></Grid></DataTemplate>") as DataTemplate; this.ItemTemplate = dt; } } } //Other code goes here }} what am i doing wrong? suggestion?

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  • Ways to update a dependent table in the same MySQL transaction?

    - by codie
    I need to update two tables inside a single transaction. The individual queries look something like this: 1. INSERT INTO t1 (col1, col2) VALUES (val1, val2) ON DUPLICATE KEY UPDATE col2 = val2; If the above query causes an insert then I need to run the following statement on the second table: 2. INSERT INTO t2 (col1, col2) VALUES (val1, val2) ON DUPLICATE KEY UPDATE col2 = col2 + val2; otherwise, 3. UPDATE t2 SET col2 = col2 - old_val2 + val2 WHERE col1 = val1; -- old_val2 is the value of t1.col2 before it was updated Right now I run a SELECT on t1 first, to determine whether statement 1 will cause an insert or update on t1. Then I run statement 1 and either of 2 and 3 inside a transaction. What are the ways in which I can do all of these inside one transaction itself? The approach I was thinking of is the following: UPDATE t2, t1 set t2.col2 = t2.col2 - t1.col2 WHERE t1.col1 = t2.col2 and t1.col1 = val1; INSERT INTO t1 (col1, col2) VALUES (val1, val2) ON DUPLICATE KEY UPDATE col2 = val2; INSERT INTO t2, t1 (t2.col1, t2.col2) VALUES (t1.col1, t1.col2) ON DUPLICATE KEY UPDATE t2.col2 = t2.col2 + t1.col2 WHERE t1.col1 = t2.col2 and t1.col1 = val1; Unfortunately, there's no multi-table INSERT... ON DUPLICATE KEY UPDATE in MySQL 5.0. What else could I do?

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  • Database for managing large volumes of (system) metrics

    - by symcbean
    Hi, I'm looking at building a system for managing and reporting stats on web page performance. I'll be collecting a lot more stats than are available in the standard log formats (approx 20 metrics) but compared to most types of database applications, the base data structure will be very simple. My problem is that I'll be accumulating a lot of data - in the region of 100,000 records (i.e. sets of metrics) per hour. Of course, resources are very limited! So that its possible to sensibly interact with the data, I'd need to consolidate each metric into one minute bins, broken down by URL, then for anything more than 1 day old, consolidated into 10 minute bins, then at 1 week, hourly bins. At the front end, I want to provide a view (prefereably as plots) of the last hour of data, with the facility for users to drill up/down through defined hierarchies of URLs (which do not always map directly to the hierarchy expressed in the path of the URL) and to view different time frames. Rather than coding all this myself and using a relational database, I was wondering if there were tools available which would facilitate both the management of the data and the reporting. I had a look at Mondrian however I can't see from the documentation I've looked at whether it's possible to drop the more granular information while maintaining the consolidated views of the data. RRDTool looks promising in terms of managing the data consolidation, but seems to be rather limited in terms of querying the dataset as a multi-dimensional/relational database. What else whould I be looking at?

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  • Rails: Multiple "types" of one model through related models?

    - by neezer
    I have a User model in my app, which I would like to store basic user information, such as email address, first and last name, phone number, etc. I also have many different types of users in my system, including sales agents, clients, guests, etc. I would like to be able to use the same User model as a base for all the others, so that I don't have to include all the fields for all the related roles in one model, and can delegate as necessary (cutting down on duplicate database fields as well as providing easy mobility from changing one user of one type to another). So, what I'd like is this: User -- first name -- last name -- email --> is a "client", so ---- client field 1 ---- client field 2 ---- client field 3 User -- first name -- last name -- email --> is a "sales agent", so ---- sales agent field 1 ---- sales agent field 2 ---- sales agent field 3 and so on... In addition, when a new user signs up, I want that new user to automatically be assigned the role of "client" (I'm talking about database fields here, not authorization, though I hope to eventually include this logic in my user authorization as well). I have a multi-step signup wizard I'm trying to build with wizardly. The first step is easy, since I'm simply calling the fields included in the base User model (such as first_name and email), but the second step is trickier since it should be calling in fields from the associated model (like--per my example above--the model client with fields client_field_1 or client_field_2, as if those fields were part of User). Does that make sense? Let me know if that wasn't clear at all, and I'll try to explain it in a different way. Can anyone help me with this? How would I do this?

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  • How to handle recurring dates (dates only) in .NET?

    - by Wayne M
    I am trying to figure out a good way to handle recurring events in .NET, specifically for an ASP.NET MVC application. The idea is that a user can create an event and specify that the event can occur repeatedly after a specific interval (e.g. "every two weeks", "once a month" and so on). What would be the best way to tackle this? My brainstorming right now is to have two tables: Job and RecurringJob. Job is the "master" record and has the description of the job as well a key to what customer it's for, while RecurringJob links back to Job and has additional info on what the occurrence frequency is (e.g. 1 for "once a month") as well as the timespan (e.g. "Weekly", "Monthly"). The issue is how to determine and set the next occurrence of the job since this will have to be something that's done regularly. I've seen two trains of thought with this: This logic should either be stored in a database column and periodically updated, or calculated on the fly in the code. Any thoughts or suggestions on tackling this? Edit: this is for a subscription based web app I'm creating to let service businesses schedule their common recurring jobs easily and track their customers. So a typical use might be to create a "Cut lawn" job for Mr Smith that occurs every month The exact date isn't important - it's the ability for the customer to see that Mr Smith gets his lawn cut every month and followup with him about it. Let me rephrase the above to better convey my idea. A sample use case for the application might be as follows: User pulls up the customer record for John Smith and clicks the Add Job link. The user fills out the form to create a job with a name of "Cut lawn", a start date of 11/15/2009, and selects a checkbox indicating that this job continually occurs. The user is presented with a secondary screen asking for the job frequency. The user indicates (haven't decided how at this point - let's assume select lists) that the job occurs once a month. User clicks save. Now, when the user views the record for John Smith, they can see that he has a job, "Cut lawn", that occurs every month starting from 11/15/2009. On the main dashboard when it's one week prior to the assumed start date, the user sees the job displayed with an indicator such as "12/15/2009 - Cut lawn (John Smith)". A week before the due date someone from the company calls him up to schedule and he says he's going to be out of town until 1/1/2010, so he wants his appointment rescheduled for that date. Our user can change the date for the job to be 1/1/2010, and now the recurrence will start one month from that date (e.g. next time will be 2/1/2010). The idea behind this is that the app is targeting businesses like lawn care, plumbers, carpet cleaners and the like where the exact date isn't as important (because it can and will change as people are busy), the key thing is to give the business an indicator that Mr. Smith's monthly service is coming up, and someone should give him a call to determine when exactly it can be scheduled for. In effect give these businesses a way to track repeat business and know when it's time to followup with a customer.

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