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• Should we retire the term "Context"?

  - by MrGumbe

  I'm not sure if there is a more abused term in the world of programming than "Context." A word that has a very clear meaning in the English language has somehow morphed into a hot mess in software development, where the definition where the connotation can be completely different based on what library you happen to be developing in. Tomcat uses the word context to mean the configuration of a web application. Java applets, on the other hand, use an AppletContext to define attributes of the browser and HTML tag that launched it, but the BeanContext is defined as a container. ASP.NET uses the HttpContext object as a grab bag of state - containing information about the current request / response, session, user, server, and application objects. Context Oriented Programming defines the term as "Any information which is computationally accessible may form part of the context upon which behavioral variations depend," which I translate as "anything in the world." The innards of the Windows OS uses the CONTEXT structure to define properties about the hardware environment. The .NET installation classes, however, use the InstallContext property to represent the command line arguments entered to the installation class. The above doesn't even touch how all of us non-framework developers have used the term. I've seen plenty of developers fall into the subconscious trap of "I can't think of anything else to call this class, so I'll name it 'WidgetContext.'" Do you all agree that before naming our class a "Context," we may want to first consider some more descriptive terms? "Environment", "Configuraton", and "ExecutionState" come readily to mind.

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• Entity Framework 1:1 Relationship Identity Colums

  - by Hupperware

  I cannot for the life of me get two separate tables to save with a relationship and two identity columns. I keep getting errors like A dependent property in a ReferentialConstraint is mapped to a store-generated column. Column: 'OlsTerminalId'. I can't imagine that this setup is abnormal. [DataContract] public class OlsData { private static readonly DateTime theUnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc); [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int OlsDataId { get; set; } [DataMember(Name = "id")] public int Id { get; set; } public DateTime Timestamp { get; set; } [DataMember(Name = "created")] [NotMapped] public double Created { get { return (Timestamp - theUnixEpoch).TotalMilliseconds; } set { Timestamp = theUnixEpoch.AddMilliseconds(value); } } [InverseProperty("OlsData")] [DataMember(Name = "terminal")] public virtual OlsTerminal OlsTerminal { get; set; } } [DataContract] public class OlsTerminal { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int OlsTerminalId { get; set; } public int OlsDataId { get; set; } [DataMember(Name = "account")] [NotMapped] public virtual OlsAccount OlsAccount { get; set; } [DataMember(Name = "terminalId")] public string TerminalId { get; set; } [DataMember(Name = "merchantId")] public string MerchantId { get; set; } public virtual OlsData OlsData { get; set; } } public class OlsDataContext : DbContext { protected override void OnModelCreating(DbModelBuilder aModelBuilder) { aModelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } public OlsDataContext(string aConnectionString) : base(aConnectionString) {} public DbSet<OlsData> OlsData { get; set; } public DbSet<OlsTerminal> OlsTerminal { get; set; } public DbSet<OlsAccount> OlsAccount { get; set; } }

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• how should i create my own 'now' / DateTime.Now ?

  - by Michel

  Hi all, i'm starting to build a part of a system which will hold a lot of DateTime validations, and a lot of 'if it was done before now' or 'if it will start in an hour etc'. Usual way to go is to use DateTime.Now to get the actual time. I predict however, that during unit test that will give me a real headache because i will have to setup my testdata for the time when the test will run in stead of use a default set of test data. So i thought: why not use my own 'now' so i can set the current datetime to any moment in time. As i don't want to set the testservers internal clock i was thinking about this solution, and i was wondering what you think of it. Base thought is that i use my own DateTime class. That class gives you the current datetime, but you can also set your own time from outside. public static class MyDateTime { private static TimeSpan _TimeDifference = TimeSpan.Zero; public static DateTime Now { get { return DateTime.Now + _TimeDifference; } } public static void SetNewNow(DateTime newNow) { _TimeDifference = newNow - DateTime.Now; } public static void AddToRealTime(TimeSpan timeSpan ) { _TimeDifference = timeSpan; } public static void SubtractFromRealTime(TimeSpan timeSpan) { _TimeDifference = - timeSpan; } }

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• C++ struct, public data members and inheritance

  - by Marius

  Is it ok to have public data members in a C++ class/struct in certain particular situations? How would that go along with inheritance? I've read opinions on the matter, some stated already here http://stackoverflow.com/questions/952907/practices-on-when-to-implement-accessors-on-private-member-variables-rather-than http://stackoverflow.com/questions/670958/accessors-vs-public-members or in books/articles (Stroustrup, Meyers) but I'm still a little bit in the shade. I have some configuration blocks that I read from a file (integers, bools, floats) and I need to place them into a structure for later use. I don't want to expose these externally just use them inside another class (I actually do want to pass these config parameters to another class but don't want to expose them through a public API). The fact is that I have many such config parameters (15 or so) and writing getters and setters seems an unnecessary overhead. Also I have more than one configuration block and these are sharing some of the parameters. Making a struct with all the data members public and then subclassing does not feel right. What's the best way to tackle that situation? Does making a big struct to cover all parameters provide an acceptable compromise (I would have to leave some of these set to their default values for blocks that do not use them)?

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• Responsive logo (image replacement) in html5boilerplate

  - by Barbara

  I'm using the responsive version of html5 boilerplate via initializr.com. My site uses a custom logo so i added the .ir class to h1 .ir { background-color: transparent; border: 0; overflow: hidden; *text-indent: -9999px; } like this <h1 class="title ir">h1.title</h1> The documentation says Add the .ir class to any element you are applying image-replacement to. When replacing an element's content with an image, make sure to also set a specific background-image: url(pathtoimage.png);, width, and height so that your replacement image appears. So I added to the code these lines .ir { background-image: url(http://i.imgur.com/yYnyJ.jpg); background-size: 100% auto; width:450px; height:450px } The problem are the specific width and height. I can't get rid of them but the logo is not responsive this way. Ideas? Here's the fiddle. http://jsfiddle.net/qeW3e/

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• `enable_shared_from_this` has a non-virtual destructor

  - by Shtééf

  I have a pet project with which I experiment with new features of the upcoming C++0x standard. While I have experience with C, I'm fairly new to C++. To train myself into best practices, (besides reading a lot), I have enabled some strict compiler parameters (using GCC 4.4.1): -std=c++0x -Werror -Wall -Winline -Weffc++ -pedantic-errors This has worked fine for me. Until now, I have been able to resolve all obstacles. However, I have a need for enable_shared_from_this, and this is causing me problems. I get the following warning (error, in my case) when compiling my code (probably triggered by -Weffc++): base class ‘class std::enable_shared_from_this<Package>’ has a non-virtual destructor So basically, I'm a bit bugged by this implementation of enable_shared_from_this, because: A destructor of a class that is intended for subclassing should always be virtual, IMHO. The destructor is empty, why have it at all? I can't imagine anyone would want to delete their instance by reference to enable_shared_from_this. But I'm looking for ways to deal with this, so my question is really, is there a proper way to deal with this? And: am I correct in thinking that this destructor is bogus, or is there a real purpose to it?

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• java.lang.ClassNotFoundException in Netbeans. 5 hours to fix

  - by user1304281

  Hi I've got to submit an interpreter assignment tonight and all of a sudden it stopped working! It was working yesterday but now when I try to create a class instance at runtime I get classnotfoundexception. My project has no libraries or dependencies, I've written everything myself. I've googled around and it seems to be an issue with classpath but I've had no luck fooling with the project properties on netbeans. Here's some code: package interpreter; import interpreter.bytecode.ByteCode; import java.io.*; import java.lang.reflect.*; class ByteCodeLoader { //.... String codeClass = CodeTable.CodeTable.get(args[0]); ByteCode bytecode = (ByteCode)(Class.forName("interpreter.bytecode."+codeClass).newInstance()); //this throws exception } all of my ByteCodes are contained within a subpackage of interpreter called interpreter.bytecode. I'll be watching this thread so I can answer/clarify any questions immediately. Thanks for your time!

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• print friendly version of floated list

  - by Brad

  I have a list of phone extensions that I want to print a friendly version of it. I have a print css for it to print appropriately onto paper, the extensions are located within an unordered list, which are floated to the left. <ul> <li>Larry Hughes <span class="ext">8291</span></li> <li>Chuck Davis <span class="ext">3141</span></li> <li>Kevin Skillis <span class="ext">5115</span></li> </ul> I float it left, and when it prints the second page, it leaves off the name part of the list (in Firefox, works fine in Google Chrome and IE), see here: http://cl.ly/de965aea63f66c13ba32 I am referring to this: http://www.alistapart.com/articles/goingtoprint/ - they mentioned something about applying a float:none; to the content part of the page. If I do that, how should I go about making the list show up in 4 columns? It is a dynamic list, pulled from a database. Any help is appreciated.

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• Symfony2 entity field type alternatives to "property" or "__toString()"?

  - by Polmonino

  Using Symfony2 entity field type one should specify property option: $builder->add('customers', 'entity', array( 'multiple' => true, 'class' => 'AcmeHelloBundle:Customer', 'property' => 'first', )); But sometimes this is not sufficient: think about two customers with the same name, so display the email (unique) would be mandatory. Another possibility is to implement __toString() into the model: class Customer { public $first, $last, $email; public function __toString() { return sprintf('%s %s (%s)', $this->first, $this->last, $this->email); } } The disadvances of the latter is that you are forced to display the entity the same way in all your forms. Is there any other way to make this more flexible? I mean something like a callback function: $builder->add('customers', 'entity', array( 'multiple' => true, 'class' => 'AcmeHelloBundle:Customer', 'property' => function($data) { return sprintf('%s %s (%s)', $data->first, $data->last, $data->email); }, ));

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• are there requirements for Struts setters beyond variable name matching?

  - by slk

  I have a model-driven Struts Web action: public class ModelDrivenAction<T extends Object> implements ModelDriven<T>, Preparable { protected Long id; protected T model; @Override public void prepare() {} public void setId(Long id) { this.id = id; } @Override public T getModel() { return model; } public void setModel(T model) { this.model = model; } } I have another action which is not currently model-driven: public class OtherAction implements Preparable { private ModelObj modelObj; private Long modelId; @Override public void prepare() { modelObj = repoService.retrieveModelById(modelId); } public void setModelId(Long modelId) { this.modelId = modelId; } } I wish to make it so, and would like to avoid having to track down all the instances in JavaScript where the action is passed a "modelId" parameter instead of "id" if at all possible. I thought this might work, so either modelId or id could be passed in: public class OtherAction extends ModelDrivenAction<ModelObj> { @Override public void prepare() { model = repoService.retrieveModelById(id); } public void setModelId(Long modelId) { this.id = modelId; } } However, server/path/to/other!method?modelId=123 is failing to set id. I thought so long as a setter matched a parameter name the Struts interceptor would call it on action invocation. Am I missing something here?

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• ASP.MVC 2 Model Data Persistance

  - by toccig

  I'm and MVC1 programmer, new to the MVC2. The data will not persist to the database in an edit scenario. Create works fine. Controller: // // POST: /Attendee/Edit/5 [Authorize(Roles = "Admin")] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(Attendee attendee) { if (ModelState.IsValid) { UpdateModel(attendee, "Attendee"); repository.Save(); return RedirectToAction("Details", attendee); } else { return View(attendee); } } Model: [MetadataType(typeof(Attendee_Validation))] public partial class Attendee { } public class Attendee_Validation { [HiddenInput(DisplayValue = false)] public int attendee_id { get; set; } [HiddenInput(DisplayValue = false)] public int attendee_pin { get; set; } [Required(ErrorMessage = "* required")] [StringLength(50, ErrorMessage = "* Must be under 50 characters")] public string attendee_fname { get; set; } [StringLength(50, ErrorMessage = "* Must be under 50 characters")] public string attendee_mname { get; set; } } I tried to add [Bind(Exclude="attendee_id")] above the Class declaration, but then the value of the attendee_id attribute is set to '0'. View (Strongly-Typed): <% using (Html.BeginForm()) {%> ... <%=Html.Hidden("attendee_id", Model.attendee_id) %> ... <%=Html.SubmitButton("btnSubmit", "Save") %> <% } %> Basically, the repository.Save(); function seems to do nothing. I imagine it has something to do with a primary key constraint violation. But I'm not getting any errors from SQL Server. The application appears to runs fine, but the data is never persisted to the Database.

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• Why does my floating div push around other divs?

  - by Meke

  I have a div which has a table which has a google map. I want to place a info box within the google map external to the map, just floating on top But I can't seem to get it right, the info div just pushes around the google map despite being on top of the map... CSS .google_map { height: 270px; width: 100%; } #flightMapInfo { position: relative; float: left; z-index: 100; color: #FFFFFF; top: 30px; left: 50px; background:#5a85a5; padding: 5px; -moz-border-radius: 10px; -webkit-border-radius: 10px; } div.tabContent { border: 1px solid #c9c3ba; padding: 0.5em; background-color: #f1f0ee; min-height: 300px; } .tableLeft { width: 75%; float: left; border-right: dotted 2px black; } HTML <div class="mapBlock tabContent"> <div id="flightMapInfo">WHARGL</div> <table class="tableLeft"> <tr><td><div id="flightMap" class="google_map"></div> </table></td></tr></div>

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• why does this knockout method receive a form element instead of the object its nested in?

  - by ladookie

  I have this HTML: <ul class="chat_list" data-bind="foreach: chats"> <li> <div class="chat_response" data-bind="visible: CommentList().length == 0"> <form data-bind="submit: $root.addComment"> <input class="comment_field" placeholder="Comment…" data-bind="value: NewCommentText" /> </form> </div> </li> </ul> and this JavaScript: function ChatListViewModel(chats) { // var self = this; self.chats = ko.observableArray(ko.utils.arrayMap(chats, function (chat) { return { CourseItemDescription: chat.CourseItemDescription, CommentList: ko.observableArray(chat.CommentList), CourseItemID: chat.CourseItemID, UserName: chat.UserName, ChatGroupNumber: chat.ChatGroupNumber, ChatCount: chat.ChatCount, NewCommentText: ko.observable("") }; })); self.newChatText = ko.observable(); self.addComment = function (chat) { var newComment = { CourseItemDescription: chat.NewCommentText(), ParentCourseItemID: chat.CourseItemID, CourseID: $.CourseLogic.dataitem.CourseID, AccountID: $.CourseLogic.dataitem.AccountID, SystemObjectID: $.CourseLogic.dataitem.CommentSystemObjectID, SystemObjectName: "Comments", UserName: chat.UserName }; chat.CommentList.push(newComment); chat.NewCommentText(""); }; } ko.applyBindings(new ChatListViewModel(initialData)); When I go into the debugger it shows that the chat parameter of the addComment() function is a form element instead of a chat object. Why is this happening?

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• Saving tags into a database table in CakePHP

  - by Cameron

  I have the following setup for my CakePHP app: Posts id title content Topics id title Topic_Posts id topic_id post_id So basically I have a table of Topics (tags) that are all unique and have an id. And then they can be attached to post using the Topic_Posts join table. When a user creates a new post they will fill in the topics by typing them in to a textarea separated by a comma which will then save these into the Topics table if they do not already exist and then save the references into the Topic_posts table. I have the models set up like so: Post model: class Post extends AppModel { public $name = 'Post'; public $hasAndBelongsToMany = array( 'Topic' => array('with' => 'TopicPost') ); } Topic model: class Topic extends AppModel { public $hasMany = array( 'TopicPost' ); } TopicPost model: class TopicPost extends AppModel { public $belongsTo = array( 'Topic', 'Post' ); } And for the New post method I have this so far: public function add() { if ($this->request->is('post')) { //$this->Post->create(); if ($this->Post->saveAll($this->request->data)) { // Redirect the user to the newly created post (pass the slug for performance) $this->redirect(array('controller'=>'posts','action'=>'view','id'=>$this->Post->id)); } else { $this->Session->setFlash('Server broke!'); } } } As you can see I have used saveAll but how do I go about dealing with the Topic data?

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• Two entities with @ManyToOne joins the same table

  - by Ivan Yatskevich

  I have the following entities Student @Entity public class Student implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Teacher @Entity public class Teacher implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Task @Entity public class Task implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "student_id") }) private Student author; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "teacher_id") }) private Teacher curator; //getters and setters } Consider that author and curator are already stored in DB and both are in the attached state. I'm trying to persist my Task: Task task = new Task(); task.setAuthor(author); task.setCurator(curator); entityManager.persist(task); Hibernate executes the following SQL: insert into student_task (teacher_id, id) values (?, ?) which, of course, leads to null value in column "student_id" violates not-null constraint Can anyone explain this issue and possible ways to resolve it?

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• Using a Form With Variables as Part of a Function

  - by John

  Hello, Could the form below be part of a function? I am wondering if it might not be able to be part of a function since it has variables. Thanks in advance, John echo '<form action="http://www...com/sandbox/comments/comments2.php" method="post"> <input type="hidden" value="'.$_SESSION['loginid'].'" name="uid"> <input type="hidden" value="'.$submissionid.'" name="submissionid"> <input type="hidden" value="'.$submission.'" name="submission"> <input type="hidden" value="'.$url.'" name="url"> <input type="hidden" value="'.$submittor.'" name="submittor"> <input type="hidden" value="'.$submissiondate.'" name="submissiondate"> <input type="hidden" value="'.$countcomments.'" name="countcomments"> <input type="hidden" value="'.$dispurl.'" name="dispurl"> <label class="addacomment" for="title">Add a comment:</label> <textarea class="commentsubfield" name="comment" type="comment" id="comment" maxlength="1000"></textarea> <div class="commentsubbutton"><input name="submit" type="submit" value="Submit"></div> </form> ';

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• Flex + PHP + ValueObjects

  - by Tempname

  I have a php/flex value object that I am using to transmit data to/from in my application. Everything works great php-flex, but I am having an issue with flex-php. In my MergeTemplateService.php service I have the following code. This is the method that flex hits directly: function updateTemplate($valueObject){ $object = DAOFactory::getMergeTemplateDAO()->update($valueObject); return $object; } I am passing a value object that from flex looks like this: (com.rottmanj.vo::MergeTemplateVO)#0 communityID = 0 creationDate = (null) enterpriseID = 0 lastModifyDate = (null) templateID = 2 templateName = "My New Test Template" userID = 0 The issue I am having is that my updateTemplate method sees the value object as an array and not an object. In my amfphp globals.php I have set my voPath as: $voPath = "services/class/dto/"; Any help with this is greatly appreciated Here are my two value objects: AS3 VO: package com.rottmanj.vo { [RemoteClass(alias="MergeTemplate")] public class MergeTemplateVO { public var templateID:int; public var templateName:String; public var communityID:int; public var enterpriseID:int; public var userID:int; public var creationDate:String; public var lastModifyDate:String public function MergeTemplateVO(data:Object = null):void { if(data != null) { templateID = data.templateID; templateName = data.templateName; communityID = data.communityID; enterpriseID = data.enterpriseID; userID = data.userID; creationDate = data.creationDate; lastModifyDate = data.lastModifyDate; } } } } PHPVO: <?php class MergeTemplate{ var $templateID; var $templateName; var $communityID; var $enterpriseID; var $userID; var $creationDate; var $lastModifyDate; var $_explictType = 'MergeTemplate'; } ?>

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• assembling an object graph without an ORM -- in the service layer or data layer?

  - by Hans Gruber

  At my current gig, our persistence layer uses IBatis going against SQL Server stored procedures (puke). IMHO, this approach has many disadvantages over the use of a "true" ORM such NHibernate or EF, but the one I'm trying to address here revolves around all the boilerplate code needed to map data from a result set into an object graph. Say I have the following DTO object graph I want to return to my presentation layer: IEnumerable<CustomerDTO> |--> IEnumerable<AddressDTO> |--> LatestOrderDTO The way I've implemented this is to have a discrete method in my DAO class to return each IEnumerable<*DTO>, and then have my service class be responsible for orchestrating the calls to the DAO. It then returns the fully assembled object graph to the client: public class SomeService(){ public SomeService(IDao someDao){ this._someDao = someDao; } public IEnumerable<CustomerDTO> ListCustomersForHistory(int brokerId){ var customers = _someDao.ListCustomersForBroker(brokerId); foreach (customer in customers){ customer.Addresses = someDao.ListCustomersAddresses(brokerId); customer.LatestOrder = someDao.GetCustomerLatestOrder(brokerId); } } return customers; } My question is should this logic belong in the service layer or the should I make my DAO such that it instead returns the assembled object graph. If I was using NHibernate, I assume that this kind of relationship association between objects comes for "free"?

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• Java generics question with wildcards

  - by Sean

  Just came across a place where I'd like to use generics and I'm not sure how to make it work the way I want. I have a method in my data layer that does a query and returns a list of objects. Here's the signature. public List getList(Class cls, Map query) This is what I'd like the calling code to look like. List<Whatever> list = getList(WhateverImpl.class, query); I'd like to make it so that I don't have to cast this to a List coming out, which leads me to this. public <T> List<T> getList(Class<T> cls, Map query) But now I have the problem that what I get out is always the concrete List<WhateverImpl> passed in whereas I'd like it to be the Whatever interface. I tried to use the super keyword but couldn't figure it out. Any generics gurus out there know how this can be done?

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• Is there a better way to write this repetitive event-declaration code in C# when implementing an int

  - by Damien Wildfire

  I have a lot of code like the following, where I explicitly implement some events required by an interface. public class IMicrowaveNotifier { event EventHandler<EventArgs> DoorClosed; event EventHandler<EventArgs> LightbulbOn; // ... } public class Microwave : IMicrowaveNotifier { private EventHandler<EventArgs> _doorClosed; event EventHandler<EventArgs> IMicrowaveNotifier.DoorClosed { add { lock (this) _doorClosed += value; } remove { lock (this) _doorClosed -= value; } } private EventHandler<EventArgs> _lightbulbOn; event EventHandler<EventArgs> IMicrowaveNotifier.LightbulbOn { add { lock (this) _lightbulbOn += value; } remove { lock (this) _lightbulbOn -= value; } } // ... } You can see that much of this is boilerplate. In Ruby I'd be able to do something like this: class Microwave has_events :door_closed, :lightbulb_on, ... end Is there a similar shorter way of removing this boilerplate in C#? Update: I left a very important part out of my example: namely, the events getting implemented are part of an interface, and I want to implement it explicitly. Sorry for not mentioning this earlier!

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• java - question about thread abortion and deadlock - volatile keyword

  - by Tiyoal

  Hello all, I am having some troubles to understand how I have to stop a running thread. I'll try to explain it by example. Assume the following class: public class MyThread extends Thread { protected volatile boolean running = true; public void run() { while (running) { synchronized (someObject) { while (someObject.someCondition() == false && running) { try { someObject.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } // do something useful with someObject } } } public void halt() { running = false; interrupt(); } } Assume the thread is running and the following statement is evaluated to true: while (someObject.someCondition() == false && running) Then, another thread calls MyThread.halt(). Eventhough this function sets 'running' to false (which is a volatile boolean) and interrupts the thread, the following statement is still executed: someObject.wait(); We have a deadlock. The thread will never be halted. Then I came up with this, but I am not sure if it is correct: public class MyThread extends Thread { protected volatile boolean running = true; public void run() { while (running) { synchronized (someObject) { while (someObject.someCondition() == false && running) { try { someObject.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } // do something useful with someObject } } } public void halt() { running = false; synchronized(someObject) { interrupt(); } } } Is this correct? Is this the most common way to do this? This seems like an obvious question, but I fail to come up with a solution. Thanks a lot for your help.

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• c++ figuring out memory layout of members programatically

  - by anon

  Suppose in one program, I'm given: class Foo { int x; double y; char z; }; class Bar { Foo f1; int t; Foo f2; }; int main() { Bar b; bar.f1.z = 'h'; bar.f2.z = 'w'; ... some crap setting value of b; FILE *f = fopen("dump", "wb"); // c-style file fwrite(&b, sizeof(Bar), 1, f); } Suppose in another program, I have: int main() { File *f = fopen("dump", "rb"); std::string Foo = "int x; double y; char z;"; std::string Bar = "Foo f1; int t; Foo f2;"; // now, given this is it possible to read out // the value of bar.f1.z and bar.f2.z set earlier? } WHat I'm asking is: given I have the types of a class, can I figure out how C++ lays it out?

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• Howw to add new value with generic Repository if there are foreign keys (EF-4)?

  - by Phsika

  i try to write a kind of generic repository to add method. Everything is ok to add but I have table which is related with two tables with FOREIGN KEY.But Not working because of foreign key public class DomainRepository<TModel> : IDomainRepository<TModel> where TModel : class { #region IDomainRepository<T> Members private ObjectContext _context; private IObjectSet<TModel> _objectSet; public DomainRepository() { } public DomainRepository(ObjectContext context) { _context = context; _objectSet = _context.CreateObjectSet<TModel>(); } //do something..... public TModel Add<TModel>(TModel entity) where TModel : IEntityWithKey { EntityKey key; object originalItem; key = _context.CreateEntityKey(entity.GetType().Name, entity); _context.AddObject(key.EntitySetName, entity); _context.SaveChanges(); return entity; } //do something..... } Calling REPOSITORY: //insert-update-delete public partial class AddtoTables { public table3 Add(int TaskId, int RefAircraftsId) { using (DomainRepository<table3> repTask = new DomainRepository<table3>(new TaskEntities())) { return repTask.Add<table3>(new table3() { TaskId = TaskId, TaskRefAircraftsID = RefAircraftsId }); } } } How to add a new value if this table includes foreign key relation

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• What's the correct way to pass parameters from VBScript to COM interface implemented in C#?

  - by nopopem

  I'm trying to expose a fairly simple C# class to COM which should be usable from VBScript (among others). Some objects need to be created via COM calls and will be used in furter calls later on. The definition of the exposed classes and interfaces looks like this: namespace Test { [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)] public interface IComInterface { IFoo CreateFoo(); void UseFoo(int x, IFoo f); } [ClassInterface(ClassInterfaceType.None)] public sealed class CComInterface : IComInterface { public CComInterface() {} public IFoo CreateFoo() { return new Foo(); } public void UseFoo(int x, IFoo f) { f.Bar(); } } [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)] public interface IFoo { void Bar(); } [ClassInterface(ClassInterfaceType.None)] public class Foo : IFoo { internal Foo() {} public void Bar() {} } } The simplest thinkable COM client in VBScript does this: Dim ci Set ci = WScript.CreateObject("Test.CComInterface") Dim foo Set foo = ci.CreateFoo foo.Bar ci.UseFoo 0, foo While the call to Bar succeeds, calling UseFoo fails with "Error 5: invalid procedure call or invalid argument" The generated IDL seems ok to me: dispinterface IComInterface { properties: methods: [id(0x60020003)] IFoo* CreateFoo(); [id(0x60020004)] void UseFoo( [in] long x, [in] IFoo* f); }; The vbs call succeeds when I wrap the second parameter in parentheses like this: ci.UseFoo 0, (foo) As far as I understand (I'm no VBScript expert however) this forces the reference to foo to be passed by value, i.e. a copy of the reference is being made. How can I change the interface so that it can be called with the foo reference directly? Since this will be a public interface used by customers I don't like the idea of having to explain why all the objects created need to be passed back in an extra pair of parentheses...

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• C++ Constructor With Parameters Won't Initialize, Errors C2059 and C2228

  - by Some Girl

  I'm a C# programmer trying to muddle through C++ to create a Windows Forms Application. I have a Windows Form that makes use of a user-created class. Basically I'm trying to use a constructor that takes parameters, but my form won't let me initialize the object with parameter. Here's the code, hopefully somebody can explain the problem to me because I'm completely baffled... Here's my header file: BankAcct.h public ref class BankAcct { private: int money; public: BankAcct(); BankAcct(int); void Deposit(int); void GetBalance(int&); }; And my definition file: BankAcct.cpp #include "StdAfx.h" #include "BankAcct.h" BankAcct::BankAcct() { money = 0; } BankAcct::BankAcct(int startAmt) { money = startAmt; } void BankAcct::Deposit(int depAmt) { money += depAmt; } void BankAcct::GetBalance(int& balance) { balance = money; } And finally my main form. Won't copy the whole thing, of course, but I'm trying to declare the new bank account object, and start it with a balance of say $50. private: BankAcct myAccount(50); //does not work! WHY?? //private: //BankAcct myAccount; //works then in the form constructor my code is this: public: frmBank(void) { InitializeComponent(); int bal; myAccount.GetBalance(bal); lblBankBalance->Text += Convert::ToString(bal); } I've included the BankAcct.h file at the top of my frmBank.h, what else am I doing wrong here? It works great if I use the default constructor (the one that starts the bank balance at zero). I get the following error messages: error C2059: syntax error: 'constant' and error C2228: left of '.GetBalance' must have class/struct/union Thank you for any and all help on this one!!

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