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  • Qt Socket blocking functions required to run in QThread where created. Any way past this?

    - by Alexander Kondratskiy
    The title is very cryptic, so here goes! I am writing a client that behaves in a very synchronous manner. Due to the design of the protocol and the server, everything has to happen sequentially (send request, wait for reply, service reply etc.), so I am using blocking sockets. Here is where Qt comes in. In my application I have a GUI thread, a command processing thread and a scripting engine thread. I create the QTcpSocket in the command processing thread, as part of my Client class. The Client class has various methods that boil down to writing to the socket, reading back a specific number of bytes, and returning a result. The problem comes when I try to directly call Client methods from the scripting engine thread. The Qt sockets randomly time out and when using a debug build of Qt, I get these warnings: QSocketNotifier: socket notifiers cannot be enabled from another thread QSocketNotifier: socket notifiers cannot be disabled from another thread Anytime I call these methods from the command processing thread (where Client was created), I do not get these problems. To simply phrase the situation: Calling blocking functions of QAbstractSocket, like waitForReadyRead(), from a thread other than the one where the socket was created (dynamically allocated), causes random behaviour and debug asserts/warnings. Anyone else experienced this? Ways around it? Thanks in advance.

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  • How to give the menus associated with dojo's dijit.ComboBox different css from those of dijit.Menu

    - by sprugman
    When you use a dijit.ComboBox, the type ahead suggestions get implemented as a dijit.Menu. I've got a design which calls for the matched portion of the suggestion rows to be normal, and the unmatched portion to be bold. The structure that dojo creates is like this: <ul class="dijitReset dijitMenu"> <li role="option" class="dijitReset dijitMenuItem"> <span class="dijitComboBoxHighlightMatch">Ch</span>oice One </li> <li role="option" class="dijitReset dijitMenuItem"> <span class="dijitComboBoxHighlightMatch">Ch</span>oice Two </li> </ul> So I can target the matched part, but not the unmatched part. So my css needs to be something like: .dijitMenuItem { font-weight: bold; } .dijitMenuItem .dijitComboBoxHighlightMatch { font-weight: normal; } The problem is, if I do that, all menus will be bolded, and I don't want that. Just doing something like this: <select dojoType="dijit.form.ComboBox" class="foobar">[options]</select> puts the foobar class in the ComboBox, but the menu is an independent node not under that hierarchy. What's the easiest way to add a css class around the popup menu that the ComboBox generates?

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  • How to perform spatial partitioning in n-dimensions?

    - by kevin42
    I'm trying to design an implementation of Vector Quantization as a c++ template class that can handle different types and dimensions of vectors (e.g. 16 dimension vectors of bytes, or 4d vectors of doubles, etc). I've been reading up on the algorithms, and I understand most of it: here and here I want to implement the Linde-Buzo-Gray (LBG) Algorithm, but I'm having difficulty figuring out the general algorithm for partitioning the clusters. I think I need to define a plane (hyperplane?) that splits the vectors in a cluster so there is an equal number on each side of the plane. [edit to add more info] This is an iterative process, but I think I start by finding the centroid of all the vectors, then use that centroid to define the splitting plane, get the centroid of each of the sides of the plane, continuing until I have the number of clusters needed for the VQ algorithm (iterating to optimize for less distortion along the way). The animation in the first link above shows it nicely. My questions are: What is an algorithm to find the plane once I have the centroid? How can I test a vector to see if it is on either side of that plane?

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  • passive view and display logic

    - by genesys
    Hi! In MVC and MVP and similar patterns there's often the approach of the "passive view" which is as stupid as possible. This should facilitate unit testing and create a clearer separation of view and model. I know that those patterns come in very different flavours and especially the understanding of MVP seems to differ from article to article. Therefore my question is not "how do i implement this pattern correctly". I want to improve view and model separation and go for better testability of the application. Therefore i'd like to go for a passive view. But my question is, where would you put logic that is clearly only view related? like a textviewer should scroll the text when the scrollbar is moved. would you put the logic for this into the Presenter? Let's say the textviewer has some extended functionality. like setting markings on textpassages. The logic for this makes clearly sense to be put into the Presenter. However, if it is mixed with all the 'direct' logic of the view (like scrolling the text) the Presenter could become very big, which is also not really a nice design. So my question is where to put display related logic of a passive view and what functionallity to mix in the Presenter. Thanks!

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  • Creating/Maintaining a large project-agnostic code library

    - by bufferz
    In order to reduce repetition and streamline testing/debugging, I'm trying to find the best way to develop a group of libraries that many projects can utilize. I'd like to keep individual executable relatively small, and have shared libraries for math, database, collections, graphics, etc. that were previously scattered among several projects and in many cases duplicated (bad!). This library is to be in an SVN repo and several programmers will be working on it. This library will be in constant development along with the executables that utilize it. For example, I want a code file in ProjectA to look something like the following: using MyCompany.Math.2D; //static 2D math methods using MyCompany.Math.3D; //static #D math methods using MyCompany.Comms.SQL; //static methods for doing simple SQLDB I/O using MyCompany.Graphics.BitmapOperations; //static methods that play with bitmaps So in my ProjectA solution file in VisualStudio, in order to develop/debug the MyCompany library I have to add several projects (Math, Comms, Graphics). Things get pretty cluttered and Solution files get out of date quickly between programmer SVN commits. I'm just looking for a high level approach to maintaining a large, shared code base in an SCN repository. I am fully willing to radically redesign my approach. I'm looking for that warm fuzzy feeling you get when you're design approach is spot on and development is fluid and natural. And ideas? Thanks!!

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  • Algorithm to detect how many words typed, also multi sentence support (Java)

    - by Alex Cheng
    Hello all. Problem: I have to design an algorithm, which does the following for me: Say that I have a line (e.g.) alert tcp 192.168.1.1 (caret is currently here) The algorithm should process this line, and return a value of 4. I coded something for it, I know it's sloppy, but it works, partly. private int counter = 0; public void determineRuleActionRegion(String str, int index) { if (str.length() == 0 || str.indexOf(" ") == -1) { triggerSuggestionList(1); return; } //remove duplicate space, spaces in front and back before searching int num = str.trim().replaceAll(" +", " ").indexOf(" ", index); //Check for occurances of spaces, recursively if (num == -1) { //if there is no space //no need to check if it's 0 times it will assign to 1 triggerSuggestionList(counter + 1); counter = 0; return; //set to rule action } else { //there is a space counter++; determineRuleActionRegion(str, num + 1); } } //end of determineactionRegion() So basically I find for the space and determine the region (number of words typed). However, I want it to change upon the user pressing space bar <space character>. How may I go around with the current code? Or better yet, how would one suggest me to do it the correct way? I'm figuring out on BreakIterator for this case... To add to that, I believe my algorithm won't work for multi sentences. How should I address this problem as well. -- The source of String str is acquired from textPane.getText(0, pos + 1);, the JTextPane. Thanks in advance. Do let me know if my question is still not specific enough.

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  • Drupal: Template Files, Modules and Content Types for Advanced Theme

    - by theandym
    Intro I am in the process of trying to convert my first HTML/CSS design into a theme for Drupal. I have used ModX for quite a few designs and appreciate the ability to create different page templates and custom variables to be assigned to those templates. However I seem to be having some issues making the transition. The site I am working on theming in Drupal is for a real estate agent. Each page/section will have a different set of content associated with it and will need to display only that content. For example, there will be a page for current listings, each of which will be formatted by a custom content type. However, when I call the content on the home page (or on other pages) I do not want to see this listing data. Layout The layout of the site and the regions associated with each page/section is as follows: Home Spotlight Featured 1 Featured 2 About Spotlight Bios - Profiles of each agent (each will be a node with name, contact info, pic, etc) listed on the page; multiple nodes listed Sidebar Listings Spotlight Listings - Profiles of properties (each will be a node with locations, basic info, pic, etc) listed on the page; multiple nodes listed Sidebar Services Spotlight Content - general paragraph text area Sidebar News/Blog News/Blog Items - List of stories with summaries and links to full article Sidebar Each page/section will use the same header and footer. Issue I have done some reading on Drupal, custom content types (and CCK), Views, and Pathauto. However I have not been able to get a clear picture of how to put it all together to accomplish what I am attempting. What I really would like to know is which modules to use, how best to use them, which elements I need to use where, and what template files I should be using to theme the elements I need to use. Any help or reference to useful resources would be much appreciated.

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  • GUI for generating XML

    - by Kenston
    Hello. Does anybody know of GUIs for generating XMLs? This means the user will not be presented with an IDE with support for XML for him to type XML codes. This would be helpful for non-technical people using the system. I know this sounds easy, given many libraries that can help in generating XMLs. The issue here is that the schema is really that flexible rather than being straightforward like representing books in a library with their properties. Imagine HTML, where we can create font tags inside a body, a table, a div, or nested even within itself. The solution is a WYSIWYG application that allows user to generate html codes (XML). However, that is good for XML applied in webpages since they involve visual aspect and design. My application of XML would focus on representing some conceptual and computational definitions, much like sql-like syntax, but more than that. I'm actually after the approach or previous works done or tried, although having a library/working framework for that would be better. Btw, I'm using Java for this project. Currently, I'm just thinking of presenting element tags where user will be able to drag and drop them and nest them with each other. And perhaps, assist them through a forms in inputing values for XML attributes. I'm still hoping if there are better ideas from the community. Thank you.

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  • 1 oracle schema support large reques per day , is this safe ?

    - by Hlex
    I 'm java system designer. As we have large project to do tightly, Those projects are java api without webpage. I design to create general flow engine to support all project. This idea use 1 oracle schema , having general transaction table . And others control routing table. They all nearly complete. But DBA Team concern that he is suffered to maintain very large request to 1 schema. 1 reason is if there are problem is some table. He must offline tablespace to fix. This is problem because all project will be affected. I try to convince by split data of each table to partition by project_code & "month number to delete" . Eaxmple partition: PROJ1_05 PROJ1_06 PROJ1_07 PROJ2_05 PROJ2_06 PROJ2_07 and all transaction table will store on its partition. So, If there are problem on any part of tablespace then he should offline some partition and another project with use same table should able to service Transaction per day should around 10Meg Record per day. Is this a good idea? If I must use 1 schema, what is strategy to do? Do you have any comment?

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  • Find & Replace - using a Regex for this?

    - by Jack W-H
    Hey folks. Regexs make me cry, so, I came here for help. I'm looking for some tips on Find & Replace in Panic's Coda. I know the F&R is pretty advance but I'm just looking for the best way to do this. I'm trying to rewrite a 'template engine' (very basic) I have going on with a webapp I'm coding in PHP (CodeIgniter). Currently I'm calling my template like so: $this->load->view('subviews/template/headerview'); $this->load->view('subviews/template/menuview'); $this->load->view('subviews/template/sidebar'); $this->load->view('The-View-I-Want-To-Load'); // This is the important line $this->load->view('subviews/template/footerview'); However it's inefficient using five lines of code every time I want to load up a different page, in every different controller. So I rewrote it like this: $data['view'] = 'The-View-I-Want-To-Load'; $this->load->view('template',$data); That way if I need to make any major changes to the design it can easily be done from the template.php view file (which contains the header, menu, sidebar views etc. etc.). However I use the previous 5-lines all over the place in many different controllers and functions. So, my question is --- How can I find and replace the old template engine (5 lines of code) for the new one - substituting in the name of the view in the important, unique line for the one in $data['view]? Does that make any sense?! If not I'll try and rephrase! I mean, is there a way of doing this via a Regex or something? Or am I on completely the wrong lines here? Thanks for your help Jack

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  • How to properly develop and deploy features for existing asp.net applications on IIS

    - by Tomh
    My question actually consists of multiple questions. I'm frequently reading about companies who deploy a small subset of features for a select amount of customers using the live "database". Ruby on Rails and its ecosystem have deployment tools and database migrations to deploy or rollback such features in a live production or staging environment. My question, how is this done for an asp.net (mvc in particular) application? How do you test your newly released features against live data? Do you have any tools to modify the existing database and roll back changes if necessary? Do you make backups before deployment? Update Maybe I should point out that my question is not really clear, getting more answers here will help me phrase the question better. To make it easier I will describe a situation I'm commonly seeing with some of my clients. My clients have large deployments of popular web applications. They do not have staging/QA/testing servers. (yes this is not optimal). The data their apps consist of are images, xml files, user uploads and data in Sql Server. Having a few records, of their production database and a couple of dummy files is not a substitute of testing against real data in my opinion. How would you design a workflow that can create a acceptable environment to mimic a production environment before going live?

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  • Can a class inherit from LambdaExpression in .NET? Or is this not recommended?

    - by d.
    Consider the following code (C# 4.0): public class Foo : LambdaExpression { } This throws the following design-time error: Foo does not implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) There's absolutely no problem with public class Foo : Expression { } but, out of curiosity and for the sake of learning, I've searched in Google System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) and guess what: zero results returned (when was the last time you saw that?). Needless to say, I haven't found any documentation on this method anywhere else. As I said, one can easily inherit from Expression; on the other hand LambdaExpression, while not marked as sealed (Expression<TDelegate> inherits from it), seems to be designed to prevent inheriting from it. Is this actually the case? Does anyone out there know what this method is about? EDIT (1): More info based on the first answers - If you try to implement Accept, the editor (C# 2010 Express) automatically gives you the following stub: protected override Expression Accept(System.Linq.Expressions.ExpressionVisitor visitor) { return base.Accept(visitor); } But you still get the same error. If you try to use a parameter of type StackSpiller directly, the compiler throws a different error: System.Linq.Expressions.Compiler.StackSpiller is inaccessible due to its protection level. EDIT (2): Based on other answers, inheriting from LambdaExpression is not possible so the question as to whether or not it is recommended becomes irrelevant. I wonder if, in cases like this, the error message should be Foo cannot implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) because [reasons go here]; the current error message (as some answers prove) seems to tell me that all I need to do is implement Accept (which I can't do).

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  • Link click does nothing after ajax switching?

    - by Neil
    An odd case I'm trying to figure out here. I'm trying to design a mailbox system, and making some of the options ajax-y. Here's the scenario: We have a page with 2 tabs, inbox and compose. Inbox is a essentially a list of links of the form mailbox.php?msg=xxx. Clicking on the inbox or compose tabs does an ajax switch. So, let's say we're on an message page: mailbox.php?msg=123 I click on "compose" - it ajax switches to a compose form. I change my mind, click on "inbox" - it goes back to a list of messages. Note, the url has not changed at this point (all has been done through ajax). I click on the same message as before. It should go back into that message. However, nothing happens! The url it should go to (mailbox.php?msg=123) IS the url showing in the address bar, but, due to the earlier ajax activity, it's showing the inbox. Thoughts on how to resolve this? And, out of curiosity, an explanation? Normally, clicking on a link that takes you to a page you're already on will reload the page. Thanks!

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  • I have two choices of Master's classes this fall. Which is the most useful?

    - by ahplummer
    (For background purposes and context): I am a Software Engineer, and manage other Software Engineers currently. I kind of wear two hats right now: one of a programmer, and one as a 'team lead'. In this regard, I've started going back to school to get my Master's degree with an emphasis in Computer Science. I already have a Bachelor's in Computer Science, and have been working in the field for about 13 years. Our primary development environment is a Windows environment, writing in .NET, Delphi, and SQL Server. Choice #1: CST 798 DATA VISUALIZATION Course Description: Basically, this is a course on the "Processing" language: http://processing.org/ Choice #2: CST 711 INFORMATICS Course Description: (From catalog): Informatics is the science of the use and processing of data, information, and knowledge. This course covers a variety of applied issues from information technology, information management at a variety of levels, ranging from simple data entry, to the creation, design and implementation of new information systems, to the development of models. Topics include basic information representation, processing, searching, and organization, evaluation and analysis of information, Internet-based information access tools, ethics and economics of information sharing.

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  • PocketPC c++ windows message processing recursion problem

    - by user197350
    Hello, I am having a problem in a large scale application that seems related to windows messaging on the Pocket PC. What I have is a PocketPC application written in c++. It has only one standard message loop. while (GetMessage (&msg, NULL, 0, 0)) { { TranslateMessage (&msg); DispatchMessage (&msg); } } We also have standard dlgProc's. In the switch of the dlgProc, we will call a proprietary 3rd party API. This API uses a socket connection to communicate with another process. The problem I am seeing is this: whenever two of the same messages come in quickly (from the user clicking the screen twice too fast and shouldn't be) it seems as though recursion is created. Windows begins processing the first message, gets the api into a thread safe state, and then jumps to process the next (identical ui) message. Well since the second message also makes the API call, the call fails because it is locked. Because of the design of this legacy system, the API will be locked until the recursion comes back out (which also is triggered by the user; so it could be locked the entire working day). I am struggling to figure out exactly why this is happening and what I can do about it. Is this because windows recognizes the socket communication will take time and preempts it? Is there a way I can force this API call to complete before preemption? Is there a way I can slow down the message processing or re-queue the message to ensure the first will execute (capturing it and doing a PostMessage back to itself didnt work). We don't want to lock the ui down while the first call completes. Any insight is greatly appreciated! Thanks!!

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  • Rhino ServiceBus: Sagas with multiple messages

    - by illdev
    I have a saga that can handle multiple messages like so: public class OrderSaga : ISaga<Order> , InitiatedBy<StartOrderSaga> , Orchestrates<CancelOrder> , Orchestrates<PaymentForOrderReceived> , Orchestrates<CheckOrderWasPaid> , Orchestrates<OrderAbandoned> , Orchestrates<CheckOrderHasBeenShipped> , Orchestrates<OrderShipped> , Orchestrates<CheckOrderHasDelayDuringShipment> , Orchestrates<OrderArrivedAtDestination> , Orchestrates<OrderCompleted> {...} but only Orchestrates<CancelOrder seems to be picked up. So I suppose (I did not find the line, but am under a strong impression this is so), that only the first Orchestrates is registered. Probably this is by design. From what I imagined a saga to be, it seems only logical that it receives many different messages, but I might be wrong. I might be wrong with my whole assumption, too :) How am I supposed to handle this? Are Sagas supposed to only handle one (in my case) a ChangeStateMessage<State or should I wire the other ConsumerOfs/Orchestrates by hand?

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  • Best practices for managing updating a database with a complex set of changes

    - by Sarge
    I am writing an application where I have some publicly available information in a database which I want the users to be able to edit. The information is not textual like a wiki but is similar in concept because the edits bring the public information increasingly closer to the truth. The changes will affect multiple tables and the update needs to be automatically checked before affecting the public tables. I'm working on the design and I'm wondering if there are any best practices that might help with some particular issues. I want to provide undo capability. I want to show the user the combined result of all their changes. When the user says they're done, I need to check the underlying public data to make sure it hasn't been changed by somebody else. My current plan is to have the user work in a set of tables setup to be a private working area. Once they're ready they can kick off a process to check everything and update the public tables. Undo can be recorded using Command pattern saving to a table. Are there any techniques I might have missed or useful papers or patterns? Thanks in advance!

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  • Force an ASP.NET 3.5 WebSite to use version 1.0.61025.0 of System.Web.Extensions

    - by Greg
    I just upgraded my Web Site project from 2.0 to 3.5 to take advantage of the TimeZoneInfo class. When I did this, I started getting an ambiguous assembly error (*see below). The problem is, I'm not using ScriptManager, an old version of SyncFusion is. I can't upgrade SyncFusion right now, so I need to tell ASP.NET to use version 1.0.61025.0 of the assembly. I ripped out all of the 3.5 script stuff from the web.config and adding bindingRedirects to it, but it didn't work. <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <dependentAssembly> <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="3.5.0.0" newVersion="1.0.61025.0" /> </dependentAssembly> <dependentAssembly> <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="3.5.0.0" newVersion="1.0.61025.0" /> </dependentAssembly> </assemblyBinding> </runtime> The type 'System.Web.UI.ScriptManager' is ambiguous: it could come from assembly 'C:\inetpub\wwwroot\xxx\bin\System.Web.Extensions.DLL' or from assembly 'C:\WINDOWS\assembly\GAC_MSIL\System.Web.Extensions\3.5.0.0__31bf3856ad364e35\System.Web.Extensions.dll'. Please specify the assembly explicitly in the type name.

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  • Appropriate wx.Sizer(s) for the job?

    - by MetaHyperBolic
    I have a space in which I would like certain elements (represented here by A, B, D, and G) to each be in its own "corner" of the design. The corners ought to line up as if each of the four elements was repelling the other; a rectangle. This is to be contained within an unresizable panel. I will have several similar panels and want to keep the location of the elements as identical as possible. (I needed something a little more complex than a wx.Wizard, but with the same general idea.) AAAAAAAAAA BB CCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCC CCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCC DDD EEE FFF GGG A represents a text in a large font. B represents a numeric progress meter (e.g. "1 of 7") in a small font. C represents a large block of text. D, E, F, and G are buttons. The G button is separated from others for functionality. I have attempted nested wx.BoxSizers (horizontal boxes inside of one vertical box) without luck. My first problem with wx.BoxSizer is that the .SetMinSize on my last row has not been honored. The second problem is that I have no idea how to make the G button "take up space" without growing comically large, or how I can jam it up against the right edge and bottom edge. I have tried to use a wx.GridBagSizer, but ran into entirely different issues. After plowing through the various online tutorials and wxPython in Action, I'm a little frustrated. The relevant forums appear to see activity once every two weeks. "Playing around with it" has gotten me nowhere; I feel as if I am trying to smooth out a hump in ill-laid carpet.

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  • Why put a DAO layer over a persistence layer (like JDO or Hibernate)

    - by Todd Owen
    Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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  • How large a role does subjectiveness play in programming?

    - by Bob
    I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP. Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing. What role does subjectiveness play within the programming realm? Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting. The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance. But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought. It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work. Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?

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  • Child sProc cannot reference a Local temp table created in parent sProc

    - by John Galt
    On our production SQL2000 instance, we have a database with hundreds of stored procedures, many of which use a technique of creating a #TEMP table "early" on in the code and then various inner stored procedures get EXECUTEd by this parent sProc. In SQL2000, the inner or "child" sProc have no problem INSERTing into #TEMP or SELECTing data from #TEMP. In short, I assume they can all refer to this #TEMP because they use the same connection. In testing with SQL2008, I find 2 manifestations of different behavior. First, at design time, the new "intellisense" feature is complaining in Management Studio EDIT of the child sProc that #TEMP is an "invalid object name". But worse is that at execution time, the invoked parent sProc fails inside the nested child sProc. Someone suggested that the solution is to change to ##TEMP which is apparently a global temporary table which can be referenced from different connections. That seems too drastic a proposal both from the amount of work to chase down all the problem spots as well as possible/probable nasty effects when these sProcs are invoked from web applications (i.e. multiuser issues). Is this indeed a change in behavior in SQL2005 or SQL2008 regarding #TEMP (local temp tables)? We skipped 2005 but I'd like to learn more precisely why this is occuring before I go off and try to hack out the needed fixes. Thanks.

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  • How is a relative JMP (x86) implemented in an Assembler?

    - by Pindatjuh
    While building my assembler for the x86 platform I encountered some problems with encoding the JMP instruction: enc inst size in bytes EB cb JMP rel8 2 E9 cw JMP rel16 4 (because of 0x66 16-bit prefix) E9 cd JMP rel32 5 ... (from my favourite x86 instruction website, http://siyobik.info/index.php?module=x86&id=147) All are relative jumps, where the size of each encoding (operation + operand) is in the third column. Now my original (and thus fault because of this) design reserved the maximum (5 bytes) space for each instruction. The operand is not yet known, because it's a jump to a yet unknown location. So I've implemented a "rewrite" mechanism, that rewrites the operands in the correct location in memory, if the location of the jump is known, and fills the rest with NOPs. This is a somewhat serious concern in tight-loops. Now my problem is with the following situation: b: XXX c: JMP a e: XXX ... XXX d: JMP b a: XXX (where XXX is any instruction, depending on the to-be assembled program) The problem is that I want the smallest possible encoding for a JMP instruction (and no NOP filling). I have to know the size of the instruction at c before I can calculate the relative distance between a and b for the operand at d. The same applies for the JMP at c: it needs to know the size of d before it can calculate the relative distance between e and a. How do existing assemblers implement this, or how would you implement this? This is what I am thinking which solves the problem: First encode all the instructions to opcodes between the JMP and it's target, and if this region contains a variable-sized opcode, use the maximum size, i.e. 5 for JMP. Then in some conditions, the JMP is oversized (because it may fit in a smaller encoding): so another pass will search for oversized JMPs, shrink them, and move all instructions ahead), and set absolute branching instructions (i.e. external CALLs) after this pass is completed. I wonder, perhaps this is an over-engineered solution, that's why I ask this question.

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  • Which articles I've should read before starting to make my custom drawn winforms app?

    - by Dmitriy Matveev
    Hello! I'm currently developing a windows forms application with a lot of user controls. Some of them are just custom drawn buttons or panels and some of them are a compositions of these buttons and panels inside of FlowLayoutPanels and TableLayoutPanels. And the window itself is also custom drawn. I don't have much experience in winforms development, but I've made a proper decomposition of proposed design into user controls and implementation is already almost finished. I've already solved many arisen problems during development by the help of the google, msdn, SO and several dirty hacks (when nothing were helping) and still experiencing some of them. There are a lot of gaps in my knowledge base, since I don't know answers to many questions like: When I should use things like double buffer, suspended layout, suspended redraw ? What should I do with the controls which shouldn't be visible at some moment ? Common performance pitfalls (I think I've fallen in in several ones) ? So I think there should be some great articles which can give some knowledge enough to avoid most common problems and improve performance and maintainability of my application. Maybe some of you can recommend a few?

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  • How to make an entity out of a join table without primary key

    - by tputkonen
    I'm trying to generate JPA entities out of an existing database having an "interesting" design. Database has a table called UserSet, which can have links to several other UserSets. There is a one to many relation between UserSets and LinkedUserSets. LinkedUserSets also has one to one relation to UserSets. I tried to generate a JPA Entity out of the database structure using Dali JPA Tools. The resulting entity Linkeduserset misses @Id or @EmbeddedId annotation and thus failes to compile. As the resulting entity contains only two @JoinColumns (which cannot be marked as @Id), I have not so far found a way around this issue. Database structure can not be modified in any way. Is there a way to overcome this somehow? Relevant pars of create table statements: CREATE TABLE `LinkedUserSets` ( `UsrSetID` INT(11) NOT NULL DEFAULT '0' , `ChildID` INT(11) NOT NULL DEFAULT '0' , CONSTRAINT `fk_LinkedUserSets_UserSet1` FOREIGN KEY (`UsrSetID` ) REFERENCES `UserSet` (`UsrSetID` )); CREATE TABLE `UserSet` ( `UsrSetID` INT(11) NOT NULL AUTO_INCREMENT , PRIMARY KEY (`UsrSetID`), CONSTRAINT `fk_UserSet_LinkedUserSets1` FOREIGN KEY (`UsrSetID` ) REFERENCES `LinkedUserSets` (`ChildID` )); Generated entities: @Entity @Table(name="linkedusersets") public class Linkeduserset { //bi-directional many-to-one association to Userset @ManyToOne @JoinColumn(name="UsrSetID") private Userset userset1; //bi-directional one-to-one association to Userset @OneToOne @JoinColumn(name="ChildID") private Userset userset2; } @Entity @Table(name="userset") public class Userset { private static final long serialVersionUID = 1L; @Id @Column(name="UsrSetID") private int jngSetID; //bi-directional many-to-one association to Linkeduserset @OneToMany(mappedBy="userset1") private Set<Linkeduserset> linkedusersets; //bi-directional one-to-one association to Linkeduserset @OneToOne(mappedBy="userset2") private Linkeduserset linkeduserset; } Error message: Entity "Linkeduserset" has no Id or EmbeddedId

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