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  • C# ProgressBar design pattern

    - by MadSeb
    Hi, I'm working on a database upgrader application. The upgrader updates the schema of a database ( adds new columns, renames columns , adds new tables, new views to an existing database by executing SQL statements ). When a user wants to upgrade from version 1.0 to 2.0 , "Upgrader" objects are taken from an object factory and the "Execute" method of each "Upgrader" is called. The GUI of the application has a progress bar and each time an upgrader object performs a SQL statement the progress bar gets incremented. while (!version.Equal(CurrentVersion)) { IUpgrader myUpgrader = UpgraderFactory.GetUpgrader(version); myUpgrader.Execute(UpgradedFile,progressbar); version.Increment(); } My question is very simple : how should the upgrader object communicate with the progressbar. In the code above, the upgrader object is given direct access to the progressbar but I'm wondering if some better way of doing this or better design pattern exists. Regards, Seb

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  • Too many argumants for function

    - by Stas Kurilin
    I'm starting learning Lisp with Java background. In SICP's exercise there is many tasks where students should create abstract functions with many parameters, like (define (filtered-accumulate combiner null-value term a next b filter)...) in exercise 3.11. In Java (language with safe, static typing discipline) - method with more than 4 arguments usually smells, but in Lisp/Scheme it doesnt, does it? I'm wandering how many arguments do you use in you functions? If you use it in production, do you make such many layers?

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  • sqlite ERROR no such column

    - by Richard
    Hi, Does anyone here have some experience with this error? Only If I use the WHERE clause, I get this error. I use php PDO to get the results. And this is my simple table $sql = "CREATE TABLE samenvatting ( stem_id INTEGER PRIMARY KEY AUTOINCREMENT, poll_id TEXT, stem_waarde_id TEXT, totaal INTEGER )"; $crud->rawQuery($sql); $poll_id = "somepoll"; $records = $crud->rawSelect('SELECT * FROM samenvatting WHERE poll_id=´.$poll_id); pdo abstract class public function conn() { isset($this->username); isset($this->password); if (!$this->db instanceof PDO) { $this->db = new PDO($this->dsn, $this->username, $this->password); $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } } public function rawSelect($sql) { $this->conn(); return $this->db->query($sql); } Thanks, Richard

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  • ASP.NET MVC 2 form submit route issue

    - by Tomaszewski
    Hi, i'm having this issue, in ASP.NET MVC 2 where I'm adding a drop down list on the master page and filling it with data from an abstract master controller. When an option is selected an submit button clicked, it reroutes you to a new page. so lets say the page lives on http://domain.com/landingPage i'm on: http://domain.com/landingPage i select option and submit takes me to http://domain.com/landingPage/Projects/FramedPage i select again and now the post tries to go to: http://domain.com/landingPage/Projects/landingPage/Projects/FramedPage because of the action="" i have set on the form tag. Any ideas on how to go about this? MasterPage: <form method="get" action="landingPage/Projects/FramedPage"> <%= Html.DropDownList("navigationList")%> <input id="navSubmitBtn" class="btnBlue" type="submit" value="Take Me There" /> </form> Projects Controller public ActionResult FramedPage(string navigationList) { ViewData["navLink"] = navigationList; return View(); } The problem i am having is that if I am ON that page

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  • Java - getConstructor() ?

    - by msr
    Hello, I wrote the question as a comment in the code, I think its easier to understand this way. public class Xpto{ protected AbstractClass x; public void foo(){ // AbstractClass y = new ????? Car or Person ????? /* here I need a new object of this.x's type (which could be Car or Person) I know that with x.getClass() I get the x's Class (which will be Car or Person), however Im wondering how can I get and USE it's contructor */ // ... more operations (which depend on y's type) } } public abstract class AbstractClass { } public class Car extends AbstractClass{ } public class Person extends AbstractClass{ }

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  • Using ninject/autofac for a given scenario

    - by sandesh247
    I have some providers, say - <Providers> <Provider Type="Providers.IM" Name="Im"/> <Provider Type="Providers.Web" Name="Web"/> ... </Provider> Each of these providers can give me a session : <Sessions> <Session Name="GoogleIM" Provider="Im" URL="..." /> <Session Name="YahooIM" Provider="Im" URL="..." /> <Session Name="YahooWeb" Provider="Web" URL="..." /> ... </Session> Currently, I instantiate "named" sessions by looking at the provider, instantiating the type, and injecting the URL (manually). I could use a session factory, which would probably have to understand the url and return a proper session. Is there a way to handle this more elegantly/simply with ninject/autofac?

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  • Configure Hibernate validation for bean

    - by sergionni
    Hi. I need to perform validation based on SQL query result. Query is defined as annotation - as @NamedQuery in my entity bean. According to Hibernate documentation(doc), there is possibility to validate bean on following operations: pre-update pre-insert pre-delete looks like: <hibernate-configuration> <session-factory> ... <event type="pre-update"> <listener class="org.hibernate.cfg.beanvalidation.BeanValidationEventListener"/> </event> <event type="pre-insert"> <listener class="org.hibernate.cfg.beanvalidation.BeanValidationEventListener"/> </event> <event type="pre-delete"> <listener class="org.hibernate.cfg.beanvalidation.BeanValidationEventListener"/> </event> </hibernate-configuration> The question is how to connect my bean with the validation configuration, described above.

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  • Advantage of using a static member function instead of an equivalent non-static member function?

    - by jonathanasdf
    I was wondering whether there's any advantages to using a static member function when there is a non-static equivalent. Will it result in faster execution (because of not having to care about all of the member variables), or maybe less use of memory (because of not being included in all instances)? Basically, the function I'm looking at is an utility function to rotate an integer array representing pixel colours an arbitrary number of degrees around an arbitrary centre point. It is placed in my abstract Bullet base class, since only the bullets will be using it and I didn't want the overhead of calling it in some utility class. It's a bit too long and used in every single derived bullet class, making it probably not a good idea to inline. How would you suggest I define this function? As a static member function of Bullet, of a non-static member function of Bullet, or maybe not as a member of Bullet but defined outside of the class in Bullet.h? What are the advantages and disadvantages of each?

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  • How do people prove the correctness of Computer Vision methods?

    - by solvingPuzzles
    I'd like to pose a few abstract questions about computer vision research. I haven't quite been able to answer these questions by searching the web and reading papers. How does someone know whether a computer vision algorithm is correct? How do we define "correct" in the context of computer vision? Do formal proofs play a role in understanding the correctness of computer vision algorithms? A bit of background: I'm about to start my PhD in Computer Science. I enjoy designing fast parallel algorithms and proving the correctness of these algorithms. I've also used OpenCV from some class projects, though I don't have much formal training in computer vision. I've been approached by a potential thesis advisor who works on designing faster and more scalable algorithms for computer vision (e.g. fast image segmentation). I'm trying to understand the common practices in solving computer vision problems.

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  • Data-related security Implementation

    - by devdude
    Using Shiro we have a great security framework embedded in our enterprise application running on GF. You define users, roles, permissions and we can control at any fine-grain level if a user can access the application, a certain page or even click a specific button. Is there a recipe or pattern, that allows on top of that, to restrict a user from seeing certain data ? Sample: You have a customer table for 3 factories (part of one company). An admin user can see all customer records, but the user at the local factory must not see any customer data of other factories (for whatever reason). Te security feature should be part of the role definition. Thanks for any input and ideas

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  • KO 2.3.4 - Accessing validation array from callbacks in models

    - by kenny99
    Hi, Apologies if this is an oversight or sheer stupidity on my part but I can't quite figure out how to access the validation array from a callback in a model (using ORM and KO 2.3.4). I want to be able to add specific error messages to the validation array if a callback returns false. e.g This register method: public function register(array & $array, $save = FALSE) { // Initialise the validation library and setup some rules $array = Validation::factory($array) ->pre_filter('trim') ->add_rules('email', 'required', 'valid::email', array($this, 'email_available')) ->add_rules('confirm_email', 'matches[email]') ->add_rules('password', 'required', 'length[5,42]') ->add_rules('confirm_password', 'matches[password]'); return ORM::validate($array, $save); } Callback: public function email_available($value) { return ! (bool) $this->db ->where('email', $value) ->count_records($this->table_name); } I can obviously access the current model from the callback, but I was wondering what the best way to add custom error from the callback would be?

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  • What's wrong with this javascript?

    - by Arlen Beiler
    What's wrong with this code? var divarray = document.getElementById("yui-main").getElementsByTagName("div"); var articleHTML = array(); var absHTML; var keyHTML; var bodyHTML = array(); var i = 0; for ( var j in divarray) { if(divarray[i].className == "articleBody"){ alert("found"); articleHTML = divarray[i]; break; } bodyHTML[i] = ''; if(articleHTML[i].className == "issueMiniFeature"){continue;} if(articleHTML[i].className == "abstract"){absHTML = articleHTML[i]; continue;} if(articleHTML[i].className == "journalKeywords"){keyHTML = articleHTML[i]; continue;} bodyHTML[i] = articleHTML[i]; i++; } This is the error I am getting: ReferenceError: array is not defined I am using Google Chrome if it helps any.

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  • Linq Grouping by 2 keys as a one

    - by Evgeny
    Hello! I write a simple OLAP viewer for my web-site. Here are the classes (abstract example): Employee { ID; Name; Roles[]; //What Employee can do } Order { Price; Employee Manager; Employee Executive; //Maybe wrong english. The person which perform order } Employee can be Manager and Executive in the order at the same time. This means that Employee role is not fixed. I have to group orders by employees and finally get IGrouping with Employee key. So .GroupBy(el=new {el.Manager,el.Executive}) is not allowed. I considered some tricks with IEqualityComparable, but found no solution. If somrbody will help I'll be vary glad, thank you.

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  • How to show that the double-checked-lock pattern with Dictionary's TryGetValue is not threadsafe in

    - by Amir
    Recently I've seen some C# projects that use a double-checked-lock pattern on a Dictionary. Something like this: private static readonly object _lock = new object(); private static volatile IDictionary<string, object> _cache = new Dictionary<string, object>(); public static object Create(string key) { object val; if (!_cache.TryGetValue(key, out val)) { lock (_lock) { if (!_cache.TryGetValue(key, out val)) { val = new object(); // factory construction based on key here. _cache.Add(key, val); } } } return val; } This code is incorrect, since the Dictionary can be "growing" the collection in _cache.Add() while _cache.TryGetValue (outside the lock) is iterating over the collection. It might be extremely unlikely in many situations, but is still wrong. Is there a simple program to demonstrate that this code fails? Does it make sense to incorporate this into a unit test? And if so, how?

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  • ASP.NET MVC IoC usability

    - by Andrew Florko
    Hello everybody, How often do you use IoC for controllers/DAL in real projects? IoC allows to abstract application from concrete implementation with additional layer of interfaces that should be implemented. But how often concrete implementation changes? Should we really have to do job twice adding method to interface then the implementation if implementation hardly will ever be changed? I took part in about 10 asp.net projects and DAL (ORM-like and not) was never rewritten completely. Watching lots of videos I clearly understand that IoC "is cool" and the really nice way to program, but does it really needed?

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  • NHibernate mapping one table on two classes with where selection

    - by Rene Schulte
    We would like to map a single table on two classes with NHibernate. The mapping has to be dynamically depending on the value of a column. Here's a simple example to make it a bit clearer: We have a table called Person with the columns id, Name and Sex. The data from this table should be mapped either on the class Male or on the class Female depending on the value of the column Sex. In Pseudocode: create instance of Male with data from table Person where Person.Sex = 'm'; create instance of Female with data from table Person where Person.Sex = 'f'; The benefit is we have strongly typed domain models and can later avoid switch statements. Is this possible with NHibernate or do we have to map the Person table into a flat Person class first? Then afterwards we would have to use a custom factory method that takes a flat Person instance and returns a Female or Male instance. Would be good if NHibernate (or another library) can handle this.

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  • groovy call private method in Java super class

    - by Jeff Storey
    I have an abstract Java class MyAbstractClass with a private method. There is a concrete implementation MyConcreteClass. public class MyAbstractClass { private void somePrivateMethod(); } public class MyConcreteClass extends MyAbstractClass { // implementation details } In my groovy test class I have class MyAbstractClassTest { void myTestMethod() { MyAbstractClass mac = new MyConcreteClass() mac.somePrivateMethod() } } I get an error that there is no such method signature for somePrivateMethod. I know groovy can call private methods but I'm guessing the problem is that the private method is in the super class, not MyConcreteClass. Is there a way to invoke a private method in the super class like this (other than using something like PrivateAccessor)? thanks Jeff

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  • How do I implement a custom Brush in WPF?

    - by MojoFilter
    Where can I find out enough info about how Brushes work to implement my own System.Windows.Media.Brush? I can handle all of the freezable baggage, but it's not really obvious what I need to override to get it to work. Yeah, so I didn't mean that I want to use a predefined brush. I want to extend System.Windows.Media.Brush, which is an abstract class. This is all purely for my own edification. I'm not even sure what kind of brush I could make. I was just trying to learn how brushes work. As in: public AwesomeBrush : Brush { protected override Freezable CreateInstanceCore() { return new AwesomeBrush(); } ... // concrete brush stuff }

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  • jquery tabs with form help

    - by sico87
    Hello, I am implementing jQuery tabs on mysite, one of the tabs holds a form and this is my problem, the form is loaded in via ajax as it is used multiple time throughout the site. My issue is that when the form is submitted the page leaves the tabbed area, whereas I need to stay within the tabbed system. Below is the code I am using TABS HTML <div id="tabs"> <ul> <li><a href="#tabs-1">Active Categories</a></li> <li><a href="#tabs-2">De-activated Categories</a></li> <li><a href="<?=base_url();?>admin/addCategory">Add A New Category</a></li> </ul> FORM MARKUP <div id="contact_form"> <?php // open the form echo form_open(base_url().'admin/addCategory'); // categoryTitle echo form_label('Category Name', 'categoryTitle'); echo form_error('categoryTitle'); $data = array( 'name' => 'categoryTitle', 'id' => 'categoryTitle', 'value' => $categoryTitle, ); echo form_input($data); // categoryAbstract $data = array( 'name' => 'categoryAbstract', 'id' => 'categoryAbstract wysiwyg', 'value' => $categoryAbstract, ); echo form_label('Category Abstract', 'categoryAbstract'); echo form_error('categoryAbstract'); echo form_textarea($data); // categorySlug $data = array( 'name' => 'categorySlug', 'id' => 'categorySlug', 'value' => $categorySlug, ); echo form_label('Category Slug', 'categorySlug'); echo form_error('categorySlug'); echo form_input($data); // categoryIsSpecial /*$data = array( 'name' => 'categoryIsSpecial', 'id' => 'categoryIsSpecial', 'value' => '1', 'checked' => $checkedSpecial, ); echo form_label('Is Category Special?', 'categoryIsSpecial'); echo form_error('categoryIsSpecial'); echo form_checkbox($data);*/ // categoryOnline $data = array( 'name' => 'categoryOnline', 'id' => 'categoryOnline', 'value' => '1', 'checked' => $checkedOnline, ); echo form_label('Online?', 'categoryOnline'); echo form_checkbox($data); echo form_error('categoryOnline'); //hidden field check if we are adding or editing echo form_hidden('edit', $edit); echo form_hidden('categoryId', $categoryId); // categorySubmit $data = array('class' => 'submit', 'id' => 'submit', 'value'=>'Submit', 'name' => 'categorySubmit'); echo form_submit($data); echo form_close(); ?> </div> FORM PROCESS function saveCategory() { $data = array(); // we need to set the what element the form errors get displayed in $this->form_validation->set_error_delimiters('<div class="formError">', '</div>'); // we need to estabilsh some rules so the form can be submitted without error, // or if there is error then the form needs show errors. $config = array( array( 'field' => 'categoryTitle', 'label' => 'Category title', 'rules' => 'required|trim|max_length[25]|xss_clean' ), array( 'field' => 'categoryAbstract', 'label' => 'Category abstract', 'rules' => 'required|trim|max_length[150]|xss_clean' ), array( 'field' => 'categorySlug', 'label' => 'Category slug', 'rules' => 'required|trim|alpha|max_length[25]|xss_clean' ), /*array( 'field' => 'categoryIsSpecial', 'label' => 'Special category', 'rules' => 'trim|xss_clean' ),*/ array( 'field' => 'categoryOnline', 'label' => 'Category online', 'rules' => 'trim|xss_clean' ) ); $this->form_validation->set_rules($config); // with the validation rules set we can no run the validation rules over the form // if any the validation returns false then the error messages will be returned to the view // in the delimiters that we set further up the page. if($this->form_validation->run() == FALSE) { // we should reload the form $this->load->view('admin/add_category'); } }

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  • Referring to the type of an inner class in Scala

    - by saucisson
    The following code tries to mimic Polymorphic Embedding of DSLs: rather than giving the behavior in Inner, it is encoded in the useInner method of its enclosing class. I added the enclosing method so that user has only to keep a reference to Inner instances, but can always get their enclosing instance. By doing this, all Inner instances from a specific Outer instance are bound to only one behavior (but it is wanted here). abstract class Outer { sealed class Inner { def enclosing = Outer.this } def useInner(x:Inner) : Boolean } def toBoolean(x:Outer#Inner) : Boolean = x.enclosing.useInner(x) It does not compile and scala 2.8 complains about: type mismatch; found: sandbox.Outer#Inner required: _81.Inner where val _81:sandbox.Outer From Programming Scala: Nested classes and A Tour of Scala: Inner Classes, it seems to me that the problem is that useInnerexpects as argument an Inner instance from a specific Outer instance. What is the true explanation and how to solve this problem ?

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  • Is testability alone justification for dependency injection?

    - by fearofawhackplanet
    The advantages of DI, as far as I am aware, are: Reduced Dependencies More Reusable Code More Testable Code More Readable Code Say I have a repository, OrderRepository, which acts as a repository for an Order object generated through a Linq to Sql dbml. I can't make my orders repository generic as it performs mapping between the Linq Order entity and my own Order POCO domain class. Since the OrderRepository by necessity is dependent on a specific Linq to Sql DataContext, parameter passing of the DataContext can't really be said to make the code reuseable or reduce dependencies in any meaningful way. It also makes the code harder to read, as to instantiate the repository I now need to write new OrdersRepository(new MyLinqDataContext()) which additionally is contrary to the main purpose of the repository, that being to abstract/hide the existence of the DataContext from consuming code. So in general I think this would be a pretty horrible design, but it would give the benefit of facilitating unit testing. Is this enough justification? Or is there a third way? I'd be very interested in hearing opinions.

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  • Storing member function pointers of derived classes in map

    - by Kiran Mohan
    Hello, I am trying to implement a factory for two classes Circle, Square both of which inherits from Shape. class Shape { public: virtual static Shape * getInstance() = 0; }; class Circle : public Shape { public: static const std::string type; Shape * getInstance() { return new Circle; } }; const std::string Circle::type = "Circle"; class Square : public Shape { public: static const std::string type; Shape * getInstance() { return new Square; } }; const std::string Square::type = "Square"; I want to now create a map with key as shape type (string) and value as a function pointer to getInstance() of the corresponding derived class. Is it possible? Thanks, Kiran

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  • WCF Service Library Reference in a Web Form (asp.net)

    - by Abu Hamzah
    i am not sure if this is the correct way of doing but i read that you not suppose to have a WCF Service Library reference in your web form project rather you add endpoints to your web.config, is that true? here is what i have done: 1) create a WCF service library project 2) create a simple service called "MyService.svc" WebForm: 1) Create a web project 2) create a WCF Service and in it i have this code <%@ ServiceHost Language="C#" Service="WCFJQuery.ContactBLL.Implementation.ContactUs" Factory="System.ServiceModel.Activation.WebScriptServiceHostFactory" %> 3) right click on the web proejct and "Add Reference" and add teh MyService.dll reference from WCF service library project. is this something how you suppose to do?

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  • NHibernate with or without Repository

    - by Groo
    There are several similar questions on this matter, by I still haven't found enough reasons to decide which way to go. The real question is, is it reasonable to abstract the NHibernate using a Repository pattern, or not? It seems that the only reason behind abstracting it is to leave yourself an option to replace NHibernate with a different ORM if needed. But creating repositories and abstracting queries seems like adding yet another layer, and doing much of the plumbing by hand. One option is to use expose IQueryable<T> to the business layer and use LINQ, but from my experience LINQ support is still not fully implemented in NHibernate (queries simply don't always work as expected, and I hate spending time on debugging a framework). Although referencing NHibernate in my business layer hurts my eyes, it is supposed to be an abstraction of data access by itself, right? What are you opinions on this?

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  • JPA : Inheritance - Discriminator value not taken into account in generated SQL

    - by Julien
    I try to use this mapping : @Entity @Table(name="ecc.\"RATE\"") @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name="DISCRIMINATOR", discriminatorType= DiscriminatorType.STRING) public abstract class Rate extends GenericBusinessObject { ... } @Entity @DiscriminatorValue("E") public class EntranceRate extends Rate { @ManyToOne @JoinColumn(name = "\"RATES_GRID_ID\"") protected RatesGrid ratesGrid; ... } @Entity @Table(name="ecc.\"RATES_GRID\"") public class RatesGrid extends GenericBusinessObject { /** */ @OneToMany(mappedBy = "ratesGrid", targetEntity = EntranceRate.class, fetch=FetchType.LAZY) private List<EntranceRate> entranceRates; } When I try to access my entranceRates list from a ratesGrid object, I get this error : Object with id: 151 was not of the specified subclass: com.ecc.bo.rate.EntranceRate (loaded object was of wrong class class com.ecc.bo.rate.AnnualRate) Looking at the sql generated, I found no trace of "discriminator=" in the where clause. What am I doing wrong ? I use a PostGreSQL database and a Hibernate as JPA provider.

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