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• Would anybody recommend learning J/K/APL?

  - by ozan

  I came across J/K/APL a few months ago while working my way through some project euler problems, and was intrigued, to say the least. For every elegant-looking 20 line python solution I produced, there'd be a gobsmacking 20 character J solution that ran in a tenth of the time. I've been keen to learn some basic J, and have made a few attempts at picking up the vocabulary, but have found the learning curve to be quite steep. To those who are familiar with these languages, would you recommend investing some time to learn one (I'm thinking J in particular)? I would do so more for the purpose of satisfying my curiosity than for career advancement or some such thing. Some personal circumstances to consider, if you care to: I love mathematics, and use it daily in my work (as a mathematician for a startup) but to be honest I don't really feel limited by the tools that I use (like python + NumPy) so I can't use that excuse. I have no particular desire to work in the finance industry, which seems to be the main port of call for K users at least. Plus I should really learn C# as a next language as it's the primary language where I work. So practically speaking, J almost definitely shouldn't be the next language I learn. I'm reasonably familiar with MATLAB so using an array-based programming language wouldn't constitute a tremendous paradigm shift. Any advice from those familiar with these languages would be much appreciated.

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• Py_INCREF/DECREF: When

  - by Izz ad-Din Ruhulessin

  Is one correct in stating the following: If a Python object is created in a C function, but the function doesn't return it, no INCREF is needed, but a DECREF is. [false]If the function does return it, you do need to INCREF, in the function that receives the return value.[/false] When assigning C typed variables as attributes, like double, int etc., to the Python object, no INCREF or DECREF is needed. Assigning Python objects as attributes to your other Python objects goes like this: PyObject *foo; foo = bar // A Python object tmp = self->foo; Py_INCREF(foo); self->foo = foo; Py_XDECREF(tmp); //taken from the manual, but it is unclear if this works in every situation EDIT: -- can I safely use this in every situation? (haven't run into one where it caused me problems) dealloc of a Python object needs to DECREF for every other Python object that it has as an attribute, but not for attributes that are C types. Edit With 'C type as an attribute I mean bar and baz: typedef struct { PyObject_HEAD PyObject *foo; int bar; double baz; } FooBarBaz;

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• Create a Task list, with tasks without executing

  - by Ernesto Araya Eguren

  I have an async method private async Task DoSomething(CancellationToken token) a list of Tasks private List<Task> workers = new List<Task>(); and I have to create N threads that runs that method public void CreateThreads(int n) { tokenSource = new CancellationTokenSource(); token = tokenSource.Token; for (int i = 0; i < n; i++) { workers.Add(DoSomething(token)); } } but the problem is that those have to run at a given time public async Task StartAllWorkers() { if (0 < workers.Count) { try { while (0 < workers.Count) { Task finishedWorker = await Task.WhenAny(workers.ToArray()); workers.Remove(finishedWorker); finishedWorker.Dispose(); } if (workers.Count == 0) { tokenSource = null; } } catch (OperationCanceledException) { throw; } } } but actually they run when i call the CreateThreads Method (before the StartAllWorkers). I searched for keywords and problems like mine but couldn't find anything about stopping the task from running. I've tried a lot of different aproaches but anything that could solve my problem entirely. For example, moving the code from DoSomething into a workers.Add(new Task(async () => { }, token)); would run the StartAllWorkers(), but the threads will never actually start. There is another method for calling the tokenSource.Cancel().

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• Cannot clear the form after Submit using the Validation plugin in jQuery

  - by novellino

  Hello, I an quite new to jQuery and I have a problem while trying to create a form. I am using the Validation plugin for validate the email (one the form's field). When I click the Submit button I want to call my own function because I want to save the data in an XML file. This is my button: (as I understood the plugin uses "submit" for understand the button) <input type="submit" name="submit" class="submit" id="submit_btn" value="Send"/> and here is the script for the validation: <script type="text/javascript"> $(document).ready(function() { //this is my form $("#contactForm").validate(); /*save the valid data in the xml*/ $(".submit").click(function() { var email = $("input#email").val(); var subject = $("input#subject").val(); var message = $("textarea#message").val(); if (email == "" || !$("#contactForm").valid()) { return false; } var dataString = 'email='+ email + '&subject=' + subject + '&message=' + message; //alert("DATA: " +dataString); $.ajax({ type: "POST", url: "SaveData.jsp", data: dataString, success: function(data){} }); return false; }); }); </script> In general it works ok but I have two basic problems. When I click the button in the beginning having all the form empty, I get no message for the field required. Also when the data are valid and I am doing the submit, the form does not become clear after the submit. If I deleted this script code, these actions are working properly but I can not save the data! Does anyone know what is wrong? Thanks a lot!

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• accessing a method from a button within a class?

  - by flo

  #import "GameObject.h" #import "Definitions.h" @implementation GameObject @synthesize owner; @synthesize state; @synthesize mirrored; @synthesize button; @synthesize switcher; - (id) init { if ( self = [super init] ) { [self setOwner: EmptyField]; button = [UIButton buttonWithType:UIButtonTypeCustom]; [self setSwitcher: FALSE]; } return self; } - (UIButton*) display{ button.frame = CGRectMake(0, 0, GO_Width, GO_Height); [button setBackgroundImage:[UIImage imageNamed:BlueStone] forState:UIControlStateNormal]; [button addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside]; return button; } -(void)buttonPressed:(id) sender { //... } } - (void) dealloc { [super dealloc]; } @end Hi! i would like to know if the above is possible somehow within a class (in my case it is called GameObject) or if i HAVE to have the button call a methode in the viewcontroller... the above results with the app crashing. i would call display within a loop on the viewcontroller and id like to change some of the GameObjects instance variables within buttonPressed. Also id like to change some other stuff by calling some other methods from within buttonPressed but i think that will be the lesser of my problems ;) also id like to know how i can pass some variables to the buttonPressed method... cant find it anywhere :( help on this one would be much appreciated ;) thanks flo

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• SSIS Transaction with Sql Transaction

  - by Mike

  I started with a package to make sure Transactions are working correctly. The package level transaction is set to Required. I have two Execute Sql Task, one deletes rows from a table and one does 1/0, to throw the error. Both task are set to supported transaction level and Serializable IsolationLevel. That works. Now when I replace my two sql task to two separate procedure calls, the first one, ChargeInterest, runs successful but the second one, PaymentProcess, fails always saying. [Execute SQL Task] Error: Executing the query "Exec [proc_xx_NotesReceivable_PaymentProcess] ..." failed with the following error: "Uncommittable transaction is detected at the end of the batch. The transaction is rolled back.". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly. PaymentProcess being the second stored procedure. Both procedures have there own BEGIN, COMMIT AND ROLLBACKS inside the SP. I believe that the transactions are being successfully handed in the Charge Interest because I can run the following without issues or the dreaded you started with 0 and now have 1 transaction. EXEC [proc_XX_NotesReceivable_ChargeInterest] 'NR', 'M', 186, 300 EXEC [proc_XX_NotesReceivable_PaymentProcess] 'NR', 186, 300 --OR GO BEGIN TRAN EXEC [proc_XX_NotesReceivable_ChargeInterest] 'NR', 'M', 186, 300 EXEC [proc_XX_NotesReceivable_PaymentProcess] 'NR', 186, 300 ROLLBACK TRAN Now I have noticed that DTC does get kicked off in both instances? Why I am not sure because it is using the same connection. In the live example I can see the transaction get started but disappears if I put a breakpoint on the PreExecute event of the second stored procedure. What is the correct way to mingle SP transactions with SSIS transactions?

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• How to learn how to program?

  - by twinbornJoint

  I would like to know the best methods for learning to program. I've been directed towards the Python language because I was told it is good for beginners. I ultimately want to make games for OS X/iPhone. My problem is that I understand what I read but I can't apply my knowledge to anything. I am a programming noob. Should I stick with Python? (is there a better language I should be learning?) Where can I learn programming theory? I get very hyper when reading my book sometimes, any tips on staying calm and focusing? What are effective ways to learn how to program? Are there standard exercises for programming? (I feel solving problems helps my understanding immensely) Ultimately I feel like I am in a never ending tunnel that leads me no where. It feels like I am just completely unable to pursue anything in the world of programming, yet it is something I want to do very much. Thanks.

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• EOFException in ObjectInputStream thrown accessing Servlet. Only for Webstart ?!

  - by Houtman

  Hi, My app. is started from both the commandline and by using an JNLP file. Im running java version 1.6.0_14 First i had the problem that i created the Buffered input and output streams in incorrect order. Found the solution here at StackOverflow . So starting from the commandline works fine now. But when starting the app using Webstart, it ends here java.io.EOFException at java.io.ObjectInputStream$PeekInputStream.readFully(Unknown Source) at java.io.ObjectInputStream$BlockDataInputStream.readShort(Unknown Source) at java.io.ObjectInputStream.readStreamHeader(Unknown Source) at java.io.ObjectInputStream.<init>(Unknown Source) at <..>remoting.thinclient.RemoteSocketChannel.<init>(RemoteSocketChannel.java:76) I found some posts regarding similar problems; at bugs.sun.com - identifies problem as solved in 6u10(b12)? at ibm.com - identifies cookies problem The latter suggests that there is a problem in Webstart with cookies. It doesn't seem to be acknowledged as a proper java bug though.. Still i am a bit lost in the solution provided regarding the cookies. Can anyone expand on the cookie solution? Many thanks.

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• Jquery Blinking issues when using 2 .hover

  - by user1897502

  I want to do 2 .hover : first when the cursor is hover the image icons should appear on the image second when the cursor is hover a specific icon, (for exemple info) a div with the informations should appear I have nearly sucess but I have blinkin problems and when I use the two .hover function the information popup does not show up. here my html {LinkOpenTag}<div class="centrage"><div class="photoDiv"><img src="{PhotoURL-500}" alt="{PhotoAlt}" /> <div class="icons"> {block:Exif} <span class="info"><span> <div class="exif" style="display: none; opacity: 0"> <ol class="CameraMeta"> <li>{block:Camera}Camera: {Camera}{/block:Camera}</li> <li>{block:Aperture}Aperture: {Aperture}{/block:Aperture}</li> <li>{block:Exposure}Exposure: {Exposure}{/block:Exposure}</li> <li>{block:FocalLength}Focal Length: {FocalLength}{/block:FocalLength}</li> </ol> </div> {/block:Exif} </div> </div>{LinkCloseTag} and here my jquery <script type="text/javascript"> $(".photoDiv img").hover( function() { $(this).next().css("visibility", "visible"); }, function() { $(this).next().css("visibility", "hidden"); } ); $("span.info").hover( function() { $(".exif").css("display", "block"); $(".exif").css("opacity", "1"); }, function() { $(".exif").css("display", "none"); $(".exif").css("opacity", "0"); } ); Thanks for your time :)

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• Emailing an excel sheet with SSL in Python

  - by jakecar

  Hi...this is my first post so let me know if there are any common courtesies I should know about. I just started programming 8 months ago, so I am fairly new. I have been doing some projects to get better. A project I'm working on now creates an Excel sheet from inputted data. It's in Python, which I just started learning a couple of weeks ago. I'm attempting to embed part of this Excel sheet into an email, sent from my school address. I have spent hours looking this up, and to no avail. There are two problems I am asking for help with: 1) I have figured out how to send an email from my GMail account, but not from my school address. My school email uses SSL port 465, which I have tried to use, but to no avail. Unfortunately, I have been having a problem setting up outgoing email for this account on my iPhone as well. It may be related? Does anyone know of common issues relating to outgoing email with SSL and Python? 2) Excel has an option of saving a sheet as a HTML. When doing so, I copy and pasted the HTML source and emailed it as an attachment. Unfortunately, the colored text did not transfer over. Does anyone know of a better way of using Python to send an excel sheet embedded in an email? Thanks for your help!

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• Are women worse developers than men? [closed]

  - by Ekaterina

  Hi people, I am a software engineer and a woman. I constantly keep hearing all these jokes around me, about women in programming. They (they - stands for male colleagues) keep pointing out the differences in thinking between men and women. The truth is that when I started working as a developer, my colleagues gave a hard time only because I am a woman. They automatically assumed that I want to do only html and styling, and didn't even me giving me the chance to do something different. I am a .NET programmer and I really disliked (and still dislike) front-end developing. I do agree men and women think differently, but I don't agree that necessarily is a bad thing. Different approach of problems/goals brings more ideas and diversity. I really believe that there are good developer and bad developers despite the male/female factor. I am curious to hear overall opinion though. Would you not hire a woman developer only because is a woman? Cheers!

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• Designing a class in such a way that it doesn't become a "God object"

  - by devoured elysium

  I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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• Silverlight 4 ComboBox - Binding to Nullable data (tried TargetNullValue but not working as expected)

  - by Laurence

  (Please note - I am a Silverlight beginner and am looking for the simplest solution here, e.g. that doesn't involve writing/installing a replacement for the ComboBox control!) This is an issue with a Silverlight 4 application that uses the View Model (MVVM) approach. I have a simple form for editing a "Product" object. Product has a CategoryID property which is nullable (int?). A ComboBox is used to view and set the CategoryID - this is bound to an ObservableCollection of Categories. Product also has number of non-nullable properties bound to TextBoxes. I want the user to see "N/A" in the ComboBox for a product with no category, and to be use this "N/A" option to set CategoryID to null. So, I manually added a Category object with CategoryID=0 and CategoryName="N/A" to the collection; then I set TargetNullValue=0 in the SelectedValue Binding of the ComboBox. My thinking was - when the ComboBox SelectedValue was bound to a null CategoryID it would substitute zero, and therefore select the "N/A" option. When editing a Product with a non-null CategoryID, everything works. However when a null CategoryID is found, two problems occur: No option is selected in the ComboBox (its blank) The ComboBox binding seems broken from this point onwards - any Product I subsequently edit (incl. ones with a non-null CategoryID) have nothing selected in the ComboBox (its still populated with all categories - just no selected item). I've seen reports of problem #2 (here, here) but I was under the impression that #1 should have worked. What am I missing to get the "N/A" option to be selected? XAML for ComboBox: <ComboBox x:Name="cboCategory" ItemsSource="{Binding colCategories, Mode=OneWay}" SelectedValuePath="CategoryID" DisplayMemberPath="CategoryName" SelectedValue="{Binding CurrentProduct.CategoryID, Mode=TwoWay, TargetNullValue=0}" Height="24" Width="344"></ComboBox>

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• FF extension: saving a value in preferences and retrieving in the js file

  - by encryptor

  I am making an extension which should take a link as the user input only once. Then the entire extension keeps using that link on various functions in the JS file. When the user changes it, the value accessed by the js file also changes accordingly. I am using the following but it does not work for me var pref_manager = Components.classes["@mozilla.org/preferencesservice;1"].getService(Components.interfaces.nsIPrefService) function setInstance(){ if (pref_manager.prefHasUserValue("myvar")) { instance = pref_manager.getString("myvar"); alert(instance); } if(instance == null){ instance = prompt("Please enter webcenter host and port"); // Setting the value pref_manager.setString("myvar", instance); } } instance is the global variable in which i take the user input. The alert (instance) does not show up, which means there is some problem by the way i am saving the pref or extracting it. Can someone please help me with this. I have never worked with preferences before. so even if there are minor problems i might not be able to figure out.

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• Workling processes multiplying uncontrolably

  - by adam

  Hello there. We have a rails app running on passenger and we background process some tasks using a combination of RabbitMQ and Workling. The workling's worker process is started using the script/workling_client command. There is always only one worker process started, and the script/workling_client has a :multiple => false options, thus allowing only one instance. But sometimes, under mysterious circumstances which I haven't been able to track down, more worklings spawn up. If I let the system run for some time, more and more worklings appear. I'm not sure if these rogue worklings cause any problems, but it is still unsettling not to know why is it happening. We are using Monit to monitor the workling process. So if it dies, it will spawn it up again. But this still does not explain how come there are suddenly more than one of them. So my question is: does anyone know what can be cause of this and how to make it stop? Is it possible that workling sometimes dies by itself, without deleting it's pid file? Could there be something wrong with the Daemons gem workling_client is build upon?

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• Effective Method to Manage and Search Through 100,000+ Objects Instantly? (C#)

  - by Kirk

  I'm writing a media player for enthusiasts with large collections (over 100,000 tracks) and one of my main goals is speed in search. I would like to allow the user to perform a Google-esque search of their entire music collection based on these factors: Song Path and File Name Items in ID3 Tag (Title, Artist, Album, etc.) Lyrics What is the best way for me to store this data and search through it? Currently I am storing each track in an object and iterating over an array of these objects checking each of their variables for string matches based on given search text. I've run into problems though where my search is not effective because it is always a phrase search and I'm not sure how to make it more fuzzy. Would an internal DB like SQLlite be faster than this? Any ideas on how I should structure this system? I also need playlist persistence, so that when they close the app and open the app their same playlist loads immediately. How should I store the playlist information so it can load quickly when the application starts? Currently I am JSON encoding the entire playlist, storing it in a text file, and reading it into the ListView at runtime, but it is getting sluggish over 20,000 tracks. Thanks!

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• Indexing community images for google image search

  - by Vittorio Vittori

  Hi, I'm trying to understand how can I do to let my site be reachable from google image search spiders. I like how last.fm solution, and I thought to use a technique like his staff do to let google find artists images on their pages. When I'm looking for an artist and I search it on google image search, as often as not I find an image from last.fm artists page, I make an example: If I search the band Pure Reason Revolution It brings me here, the artist's image page http://www.last.fm/music/Pure+Reason+Revolution/+images/4284073 Now if I take a look to the image file, i can see it's named: http://userserve-ak.last.fm/serve/500/4284073/Pure+Reason+Revolution+4.jpg so if I try to undertand how the service works I can try to say: http://userserve-ak.last.fm/serve/ the server who serve the images 500/ the selected size for the image 4284073/ the image id for database Pure+Reason+Revolution+4.jpg the image name I thought it's difficult to think the real filename for the image is Pure+Reason+Revolution+4.jpg for image overwrite problems when an user upload it, in fact if I digit: http://userserve-ak.last.fm/serve/500/4284073.jpg I probably find the real image location and filename With this tecnique the image is highly reachable from search engines and easily archived. My question is, does exist some guide or tutorial to approach on this kind of tecniques, or something similar?

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• Using ZLib unit to compress files vs using ZipForge

  - by user193655

  There are many questions on zipping in Delphi, anyway this is not a duplicate. I am using ZipForge for zip/unzip capability in my application. Currently I use 2 features of ZipForge: 1) zip and unzip (!) 2) password protect the archives Now I am removing the password from all the archives so I need only to zip and unzip files. I zip them just for minimizing bandwith when uploading/downloading files from the server. So my idea is to process all files once for unzipping them (with password) and rezipping them without password. I have nothing against ZipForge, anyway it is an extra component, every time I upgrade to a newest Delphi version I have to wait for the new IDE support and moreover the more components the more problems during the installation. So since what I do is very simple I'd like to replace ZipForge with 2 simple functinos using the ZLib unit. I found (and tested) the functions here on Torry's. What do you think of using Zlib unit? Do you see any potential problem that I would not have with ZipForge? Can you comment on speed?

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• ArrayList<String> NullPointerException

  - by Carlucho

  Am trying to solve a labyrinth by DFS, using adj List to represent the vertices and edges of the graph. In total there are 12 nodes (3 rows[A,B,C] * 4 cols[0,..,3]). My program starts by saving all the vertex labels (A0,..C3), so far so good, then checks the adjacent nodes, also no problems, if movement is possible, it proceeds to create the edge, here its where al goes wrong. adjList[i].add(vList[j].label); I used the debugger and found that vList[j].label is not null it contains a correct string (ie. "B1"). The only variables which show null are in adjList[i], which leads me to believe i have implemented it wrongly. this is how i did it. public class GraphList { private ArrayList<String>[] adjList; ... public GraphList(int vertexcount) { adjList = (ArrayList<String>[]) new ArrayList[vertexCount]; ... } ... public void addEdge(int i, int j) { adjList[i].add(vList[j].label); //NULLPOINTEREXCEPTION HERE } ... } I will really appreaciate if anyone can point me on the right track regrading to what its going wrong... Thanks!

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• How can i get HWND of external application's listview? In Windows Api using c++

  - by Marko29

  So i am trying to make app to get content of my explorer listviews and get item text etc.. from it but here are the problems... If i inspect windows explorer folder(using spy++) with listview, just for testing purposes i will use random folder. It shows me that caption of the window is "FolderView" with class "SysListView32" and the top level window where this listview is nested is called "reference", this is also the title of windows explorer folder where all the files are. So what i do is.. HWND hWndLV = FindWindow(NULL, TEXT("reference")); // first i get hwnd of the main window, this is where listview window is also nested according to spy++, thats why i do this first. HWND child = FindWindowEx(hWndLV, NULL,NULL,TEXT("FolderView")); // trying to get hwnd of the listview here but it fails, same happens if i also put the class name along as HWND child = FindWindowEx(hWndLV, NULL,TEXT("SysListView32"),TEXT("FolderView")); I am using bool test = IsWindow(child); to test for fail, also VS debugger shows 0x0000000000 each time so i am sure i am reading results well. So i am stuck on this probably simple thing for most of people:( p.s. i am on vista64(if that matters anyhow) edit: It appears that this function works only if i search the first nested level of a parent window i am searching. So i assume what i need is a way to get handle with some sort of deep nested level search. I also tried to go step by step by defining hwnd of every parent then i use findwindowex on it but oh boy then i get to the point where there are 5 nested windows all with the same name and only one of them contains my listview, so nice uh?

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• JTA or LOCAL transactions in JPA2+Hibernate 3.6.0?

  - by Pangea

  We are in the process of re-thinking our tech stack and below are our choices (We can't live without Spring and Hibernate due to the complexity etc of the app). We are also moving from J2EE 1.4 to JEE 5. Tech stack JEE 5 JPA 2.0 (I know JEE 5 only supports JPA 1.0 but we want to use Hibernate as the JPA provider) Hibernate 3.6.0 (We already have lots of hbm files with custom types etc. so we doesn't want to migrate them at this time to JPA. This means we want both jpa/hbm mappings work together and hence the Hibernate as the JPA provider instead of using the default that comes with App Server) Now the problems is that I want to stick with local transactions but other team members want to use JTA. I have been working with J2EE for last 9 years and I've heard time and again people suggesting to stick with local transactions if I doesn't need two phase commits. This is not only for performance reasons but debugging/troubleshooting a local transaction is lot easier than a distributed transaction. My suggestion is to use spring declarative transaction management + local transactions (HibernateTransactionManager) I want to make sure if I am being paranoid or I have a valid point. I'd like to hear what the rest of the JEE world thinks. Thank you.

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• Remove pointer object whose reference is mantained in three different lists

  - by brainydexter

  I am not sure how to approach this problem: 'Player' class mantains a list of Bullet* objects: class Player { protected: std::list< Bullet* > m_pBullet_list; } When the player fires a Bullet, it is added to this list. Also, inside the constructor of bullet, a reference of the same object is updated in CollisionMgr, where CollisionMgr also mantains a list of Bullet*. Bullet::Bullet(GameGL*a_pGameGL, Player*a_pPlayer) : GameObject( a_pGameGL ) { m_pPlayer = a_pPlayer; m_pGameGL->GetCollisionMgr()->AddBullet(this); } class CollisionMgr { void AddBullet(Bullet* a_pBullet); protected: std::list< Bullet*> m_BulletPList; } In CollisionMgr.Update(); based on some conditions, I populate class Cell which again contain a list of Bullet*. Finally, certain conditions qualify a Bullet to be deleted. Now, these conditions are tested upon while iterating through a Cell's list. So, if I have to delete the Bullet object, from all these places, how should I do it so that there are no more dangling references to it? std::list< Bullet*>::iterator bullet_it; for( bullet_it = (a_pCell->m_BulletPList).begin(); bullet_it != (a_pCell->m_BulletPList).end(); bullet_it++) { bool l_Bullet_trash = false; Bullet* bullet1 = *bullet_it; // conditions would set this to true if ( l_Bullet_Trash ) // TrashBullet( bullet1 ); continue; } Also, I was reading about list::remove, and it mentions that it calls the destructor of the object we are trying to delete. Given this info, if I delete from one list, the object does not exist, but the list would still contain a reference to it..How do I handle all these problems ? Can someone please help me here ? Thanks PS: If you want me to post more code or provide explanation, please do let me know.

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• Comet (long polling) and XmlHttpRequest status

  - by chris_l

  I'm playing around a little bit with raw XmlHttpRequestObjects + Comet Long Polling. (Usually, I'd let GWT or another framework handle of this for me, but I want to learn more about it.) I wrote the following code: function longPoll() { var xhr = createXHR(); // Creates an XmlHttpRequestObject xhr.open('GET', 'LongPollServlet', true); xhr.onreadystatechange = function () { if (xhr.readyState == 4) { if (xhr.status == 200) { ... } if (xhr.status > 0) { longPoll(); } } } xhr.send(null); } ... <body onload="javascript:longPoll()">... I wrapped the longPoll() call in an if statement that checks for status > 0, because I encountered, that when I leave the page (by browsing somewhere else, or by reloading it), one last unnecessary comet call is sent. [And on Firefox, it even causes severe problems when doing a page reload, for some reason I don't fully understand yet.] Question: Is that status check the correct way to handle this problem, or is there a better solution?

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• Why do I get empty request from the Jakarta Commons HttpClient?

  - by polyurethan

  I have a problem with the Jakarta Commons HttpClient. Before my self-written HttpServer gets the real request there is one request which is completely empty. That's the first problem. The second problem is, sometimes the request data ends after the third or fourth line of the http request: POST / HTTP/1.1 User-Agent: Jakarta Commons-HttpClient/3.1 Host: 127.0.0.1:4232 For debugging I am using the Axis TCPMonitor. There every things is fine but the empty request. How I process the stream: StringBuffer requestBuffer = new StringBuffer(); InputStreamReader is = new InputStreamReader(socket.getInputStream(), "UTF-8"); int byteIn = -1; do { byteIn = is.read(); if (byteIn > 0) { requestBuffer.append((char) byteIn); } } while (byteIn != -1 && is.ready()); String requestData = requestBuffer.toString(); How I send the request: client.getParams().setSoTimeout(30000); method = new PostMethod(url.getPath()); method.getParams().setContentCharset("utf-8"); method.setRequestHeader("Content-Type", "application/xml; charset=utf-8"); method.addRequestHeader("Connection", "close"); method.setFollowRedirects(false); byte[] requestXml = getRequestXml(); method.setRequestEntity(new InputStreamRequestEntity(new ByteArrayInputStream(requestXml))); client.executeMethod(method); int statusCode = method.getStatusCode(); Have anyone of you an idea how to solve these problems? Alex

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• Using Hibernate with MS ACCESS 2007 Database (Free JDBC Driver)

  - by Quentin T.

  1. I want to do a reverse engineering action with the Hibernate plugin of Eclipse on a MS Access 2007 Database. I'm forced to use a existing MS Access 2007 db. A easy solution is to buy the HXTT. But I want to use a free driver to do my work. So I tried to apply this post : http://www.programmingforfuture.com/2011/06/how-to-use-ms-access-with-hibernate.html (That uses the SQL Server dialect and the driver sun.jdbc.odbc.JdbcOdbcDriver) Unfortunately I have an error that nobody seems to have been on the internet: Exception while generating code Reason : org.hibernate.exception.GenericJDBCException: Error while reading primary key meta data for `c:/myaccessdb.mdb`.TableTest1 I have try to change the primary key on my MS Access DB (deleting all primary key) or to try the reverse engineering on a MS ACCESS with only one table without primary key, but I got all times the problems. 2. The purpose of my job is to transfer daily (weekly) an Oracle 11g database with data from an existing database MS ACCESS 2007. And I thought to use a procedure (Hibernate EJB) Java to be launched automatically every week to do the data transfer. Is this is the best solution ? Configuration : sun.jdbc.odbc.JdbcOdbcDriver v??? Hibernate v3.4 Eclipse ps: If you are a HXTT developer or seller please be indulgent with my post ;). Making money by making people believe that you help, it's bad ! A solution is to use Derby Client driver, as the solution in the post: Does anyone know if Hibernate and java will work effectively with Access? But a clarification of the answer of Rich Seller is required. Could you explain your answer and explain your configuration (hibernate.cfg.xml, persistence.xml and what URL you use in the property name="hibernate.connection.url") without using paying HXTT driver but with the free Derby driver.

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