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  • Events and references pattern

    - by serhio
    In a project I have the following relation between BO and GUI By e.g. G could represent a graphic with time lines, C a TimeLine curve, P - points of that curve and T the time that represents each point. Each GUI object is associated with the BO corresponding object. When T changes GUI P captures the Changed event and changes its location. So, when G should be modified, it modifies internally its objects and as result T changes, P moves and the GuiG visually changes, everything is OK. But there is an inconvenient of this architecture... BO should not be recreated, because this will breack the link between BO and GUIO. In particular, GUI P should always have the same reference of T. If in a business logic I do by e.g. P1.T = new T(this.T + 10) GUI_P1 will not move anymore, because it wait an event from the reference of former P1.T object, that does not belongs to P1 anymore. So the solution was to always modify the existing objects, not to recreate it. But here is an other inconvenient: performance. Say I have a ready newC object that should replace the older one. Instead of doing G1.C = newC I should do foreach T in foreach P in C replace with T from P from newC. Is there an other more optimal way to do it?

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  • Which ORM to use?

    - by Paja
    I'm developing an application which will have these classes: class Shortcut { public string Name { get; } public IList<Trigger> Triggers { get; } public IList<Action> Actions { get; } } class Trigger { public string Name { get; } } class Action { public string Name { get; } } And I will have 20+ more classes, which will derive from Trigger or Action, so in the end, I will have one Shortcut class, 15 Action-derived classes and 5 Trigger-derived classes. My question is, which ORM will best suit this application? EF, NH, SubSonic, or maybe something else (Linq2SQL)? I will be periodically releasing new application versions, adding more triggers and actions (or changing current triggers/actions), so I will have to update database schema as well. I don't know if EF or NH provides any good methods to easily update the schema. Or if they do, is there any tutorial how to do that? I've already found this article about NH schema updating, quoting: Fortunately NHibernate provides us the possibility to update an existing schema, that is NHibernate creates an update script which can the be applied to the database. I've never found how to actually generate the update script, so I can't tell NH to update the schema. Maybe I've misread something, I just didn't found it. Last note: If you suggest EF, will be EF 1.0 suitable as well? I would rather use some older .NET than 4.0.

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  • Best place to check user authenticity in a back end module where all pages are only available to mem

    - by understack
    I've a backend module which could only be accessed by only authorized members. So I need to check authenticity for all actions and for all controllers. Currently I'm doing it inside preDispatch() functions inside controller classes. So it takes care of all the actions inside that controller. But still I've to do it for all controllers. Is there a place I could check it for all the controllers as well. So basically I want one place authenticity check for whole backend module. Can I do it in bootstrap?

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  • Shipping jar with default .properties file configurations

    - by Maxim Veksler
    Hello, I would like to include a default default.properties file in my .jar library. The idea is to allow the user to override my default is he so desires. I'm having trouble getting the classloader to play nicely with this setup, I've tried to look a at popular jars such as log4j, common-* and others and it seems that no one is implementing this idea. Am I going the wrong way? The second best thing is hard coding the values, and using the default if no .properties key has been found, but this sound oh so wrong. Suggestions?

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  • Why Does Private Access Remain Non-Private in .NET Within a Class?

    - by AMissico
    While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Foo Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error because Foo doesn't know Jack _fred = New Fred '_fred._int = 3 'expected compile error because Fred hides from Foo End Sub Private Class Fred Private _int As Integer End Class End Class Class Jack Private _int As Integer End Class

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  • EF 4 Self Tracking Entities does not work as expected.

    - by ashraf
    I am using EF4 Self Tracking Entities (VS2010 Beta 2 CTP 2 plus new T4 generator). But when I try to update entity information it does not update to database as expected. I setup 2 service calls. one for GetResource(int id) which return a resource object. the second call is SaveResource(Resource res); here is the code. public Resource GetResource(int id) { using (var dc = new MyEntities()) { return dc.Resources.Where(d => d.ResourceId == id).SingleOrDefault(); } } public void SaveResource(Resource res) { using (var dc = new MyEntities()) { dc.Resources.ApplyChanges(res); dc.SaveChanges(); // Nothing save to database. } } //Windows Console Client Calls var res = service.GetResource(1); res.Description = "New Change"; // Not updating... service.SaveResource(res); // does not change anything. It seems to me that ChangeTracker.State is always show as "Unchanged". anything wrong in this code?

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  • What is there so useful in the Decorator Pattern? My example doesn't work

    - by Green
    The book says: The decorator pattern can be used to extend (decorate) the functionality of a certain object I have a rabbit animal. And I want my rabbit to have, for example, reptile skin. Just want to decorate a common rabbit with reptile skin. I have the code. First I have abstract class Animal with everythig that is common to any animal: abstract class Animal { abstract public function setSleep($hours); abstract public function setEat($food); abstract public function getSkinType(); /* and more methods which for sure will be implemented in any concrete animal */ } I create class for my rabbit: class Rabbit extends Animal { private $rest; private $stomach; private $skinType = "hair"; public function setSleep($hours) { $this->rest = $hours; } public function setFood($food) { $this->stomach = $food; } public function getSkinType() { return $this->$skinType; } } Up to now everything is OK. Then I create abstract AnimalDecorator class which extends Animal: abstract class AnimalDecorator extends Animal { protected $animal; public function __construct(Animal $animal) { $this->animal = $animal; } } And here the problem comes. Pay attention that AnimalDecorator also gets all the abstract methods from the Animal class (in this example just two but in real can have many more). Then I create concrete ReptileSkinDecorator class which extends AnimalDecorator. It also has those the same two abstract methods from Animal: class ReptileSkinDecorator extends AnimalDecorator { public function getSkinColor() { $skin = $this->animal->getSkinType(); $skin = "reptile"; return $skin; } } And finaly I want to decorate my rabbit with reptile skin: $reptileSkinRabbit = ReptileSkinDecorator(new Rabbit()); But I can't do this because I have two abstract methods in ReptileSkinDecorator class. They are: abstract public function setSleep($hours); abstract public function setEat($food); So, instead of just re-decorating only skin I also have to re-decorate setSleep() and setEat(); methods. But I don't need to. In all the book examples there is always ONLY ONE abstract method in Animal class. And of course it works then. But here I just made very simple real life example and tried to use the Decorator pattern and it doesn't work without implementing those abstract methods in ReptileSkinDecorator class. It means that if I want to use my example I have to create a brand new rabbit and implement for it its own setSleep() and setEat() methods. OK, let it be. But then this brand new rabbit has the instance of commont Rabbit I passed to ReptileSkinDecorator: $reptileSkinRabbit = ReptileSkinDecorator(new Rabbit()); I have one common rabbit instance with its own methods in the reptileSkinRabbit instance which in its turn has its own reptileSkinRabbit methods. I have rabbit in rabbit. But I think I don't have to have such possibility. I don't understand the Decarator pattern right way. Kindly ask you to point on any mistakes in my example, in my understanding of this pattern. Thank you.

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  • Need some help understanding this problem

    - by Legend
    I was wondering if someone could help me understand this problem. I prepared a small diagram because it is much easier to explain it visually. Problem I am trying to solve: 1. Constructing the dependency graph Given the connectivity of the graph and a metric that determines how well a node depends on the other, order the dependencies. For instance, I could put in a few rules saying that node 3 depends on node 4 node 2 depends on node 3 node 3 depends on node 5 But because the final rule is not "valuable" (again based on the same metric), I will not add the rule to my system. 2. Execute the request order Once I built a dependency graph, execute the list in an order that maximizes the final connectivity. First and foremost, I am wondering if I constructed the problem correctly and if I should be aware of any corner cases. Secondly, is there a closely related algorithm that I can look at? Currently, I am thinking of something like Feedback Arc Set or the Secretary Problem but I am a little confused at the moment. Any suggestions? PS: I am a little confused about the problem myself so please don't flame on me for that. If any clarifications are needed, I will try to update the question.

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  • Normalizing Item Names & Synonyms

    - by RabidFire
    Consider an e-commerce application with multiple stores. Each store owner can edit the item catalog of his store. My current database schema is as follows: item_names: id | name | description | picture | common(BOOL) items: id | item_name_id | picture | price | description | picture item_synonyms: id | item_name_id | name | error(BOOL) Notes: error indicates a wrong spelling (eg. "Ericson"). description and picture of the item_names table are "globals" that can optionally be overridden by "local" description and picture fields of the items table (in case the store owner wants to supply a different picture for an item). common helps separate unique item names ("Jimmy Joe's Cheese Pizza" from "Cheese Pizza") I think the bright side of this schema is: Optimized searching & Handling Synonyms: I can query the item_names & item_synonyms tables using name LIKE %QUERY% and obtain the list of item_name_ids that need to be joined with the items table. (Examples of synonyms: "Sony Ericsson", "Sony Ericson", "X10", "X 10") Autocompletion: Again, a simple query to the item_names table. I can avoid the usage of DISTINCT and it minimizes number of variations ("Sony Ericsson Xperia™ X10", "Sony Ericsson - Xperia X10", "Xperia X10, Sony Ericsson") The down side would be: Overhead: When inserting an item, I query item_names to see if this name already exists. If not, I create a new entry. When deleting an item, I count the number of entries with the same name. If this is the only item with that name, I delete the entry from the item_names table (just to keep things clean; accounts for possible erroneous submissions). And updating is the combination of both. Weird Item Names: Store owners sometimes use sentences like "Harry Potter 1, 2 Books + CDs + Magic Hat". There's something off about having so much overhead to accommodate cases like this. This would perhaps be the prime reason I'm tempted to go for a schema like this: items: id | name | picture | price | description | picture (... with item_names and item_synonyms as utility tables that I could query) Is there a better schema you would suggested? Should item names be normalized for autocomplete? Is this probably what Facebook does for "School", "City" entries? Is the first schema or the second better/optimal for search? Thanks in advance! References: (1) Is normalizing a person's name going too far?, (2) Avoiding DISTINCT

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  • Passing data between objects in Chain of Responsibility pattern

    - by AbrahamJP
    While implementing the Chain of Responsibility pattern, i came across a dilemma om how to pass data between objects in the chain. The datatypes passed between object in the chain can differ for each object. As a temporary fix I had created a Static class containing a stack where each object in the chain can push the results to the stack while the next object in the chain could pop the results from the stack. Here is a sample code on what I had implemented. public interface IHandler { void Process(); } public static class StackManager { public static Stack DataStack = new Stack(); } //This class doesn't require any input to operate public class OpsA : IHandler { public IHandler Successor {get; set; } public void Process() { //Do some processing, store the result into Stack var ProcessedData = DoSomeOperation(); StackManager.DataStack.Push(ProcessedData); if(Successor != null) Successor(); } } //This class require input data to operate upon public class OpsB : IHandler { public IHandler Successor {get; set; } public void Process() { //Retrieve the results from the previous Operation var InputData = StackManager.DataStack.Pop(); //Do some processing, store the result into Stack var NewProcessedData = DoMoreProcessing(InputData); StackManager.DataStack.Push(NewProcessedData); if(Successor != null) Successor(); } } public class ChainOfResponsibilityPattern { public void Process() { IHandler ProcessA = new OpsA(); IHandler ProcessB = new OpsB(); ProcessA.Successor = ProcessB; ProcessA.Process(); } } Please help me to find a better approach to pass data between handlers objects in the chain.

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  • Immutable classes in C++

    - by ereOn
    Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

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  • Zend_Auth and database session SaveHandler

    - by takeshin
    I have created Zend_Auth adapter implementing Zend_Auth_Adapter_Interface (similar to Pádraic's adapter) and created simple ACL plugin. Everything works fine with default session handler. So far, so good. As a next step I have created custom Session SaveHandler to persist session data in the database. My implementation is very similar to this one from parables-demo. Seems that everything is working fine. Session data are properly saved to the database, session objects are serialized, but authentication does not work when I enable this custom SaveHandler. I have debugged the authentication and all works fine up till the next request, when the authentication data are lost. I suspected, that is has something to do with the fact, that I use $adapter->write($object) instead $adapter->write($string), but the same happens with strings. I'm bootstrapping Zend_Application_Resource_Session in the first Bootstrap method, as early as possible. Does Zend_Auth need any extra configuration to persist data in the database? Why the authentity is being lost?

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  • Accessing a Class Member from a First-Class Function

    - by dbyrne
    I have a case class which takes a list of functions: case class A(q:Double, r:Double, s:Double, l:List[(Double)=>Double]) I have over 20 functions defined. Some of these functions have their own parameters, and some of them also use the q, r, and s values from the case class. Two examples are: def f1(w:Double) = (d:Double) => math.sin(d) * w def f2(w:Double, q:Double) = (d:Double) => d * q * w The problem is that I then need to reference q, r, and s twice when instantiating the case class: A(0.5, 1.0, 2.0, List(f1(3.0), f2(4.0, 0.5))) //0.5 is referenced twice I would like to be able to instantiate the class like this: A(0.5, 1.0, 2.0, List(f1(3.0), f2(4.0))) //f2 already knows about q! What is the best technique to accomplish this? Can I define my functions in a trait that the case class extends? EDIT: The real world application has 7 members, not 3. Only a small number of the functions need access to the members. Most of the functions don't care about them.

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  • Sorting data by relevance, from multiple tables

    - by Oden
    Hey, How is it possible to sort data from multiple tables by relevance? My table structure is following: I have 3 tables in my database, one table contains the name of solar systems, the second for e.g. of planets. There is one more table, witch is a connection between solar systems and planets. If I want to get data of a planet, witch is in the Milky Way, i post this data to the server, and it gives me a multi-dimensional array witch contains: The Milky Way, with every planet in it Every planet, witch name contains the string Milky Way (maybe thats a bat example because i don't think that theres but one planet with this name, but the main concept is on file) But, i want to set the most relevant restaurants to the top of the array. (for the relevance i would check the description of the restaurants or something like that) So, how would you do that kind of data sorting?

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  • ASP.net MVC DropLownList db.SaveChanges not saving selection

    - by WMIF
    I have looked through a ton of tutorials and suggestions on how to work with DropDownList in MVC. I was able to get most of it working, but the selected item is not saving into the database. I am using MVC 3 and Razor for the view. My DropDownList is getting created with the correct values and good looking HTML. When I set a breakpoint, I can see the correct selected item ID in the model getting sent to controller. When the view goes back to the index, the DropDownList value is not set. The other values save just fine. Here are the related views. The DropDownList is displaying a list of ColorModel names as text with the ID as the value. public class ItemModel { [Key] public int ItemID { get; set; } public string Name { get; set; } public string Description { get; set; } public virtual ColorModel Color { get; set; } } public class ItemEditViewModel { public int ItemID { get; set; } public string Name { get; set; } public string Description { get; set; } public int ColorID { get; set; } public IEnumerable<SelectListItem> Colors { get; set; } } public class ColorModel { [Key] public int ColorID { get; set; } public string Name { get; set; } public virtual IList<ItemModel> Items { get; set; } } Here are the controller actions. public ActionResult Edit(int id) { ItemModel itemmodel = db.Items.Find(id); ItemEditViewModel itemEditModel; itemEditModel = new ItemEditViewModel(); itemEditModel.ItemID = itemmodel.ItemID; if (itemmodel.Color != null) { itemEditModel.ColorID = itemmodel.Color.ColorID; } itemEditModel.Description = itemmodel.Description; itemEditModel.Name = itemmodel.Name; itemEditModel.Colors = db.Colors .ToList() .Select(x => new SelectListItem { Text = x.Name, Value = x.ColorID.ToString() }); return View(itemEditModel); } [HttpPost] public ActionResult Edit(ItemEditViewModel itemEditModel) { if (ModelState.IsValid) { ItemModel itemmodel; itemmodel = new ItemModel(); itemmodel.ItemID = itemEditModel.ItemID; itemmodel.Color = db.Colors.Find(itemEditModel.ColorID); itemmodel.Description = itemEditModel.Description; itemmodel.Name = itemEditModel.Name; db.Entry(itemmodel).State = EntityState.Modified; db.SaveChanges(); return RedirectToAction("Index"); } return View(itemEditModel); } The view has this for the DropDownList, and the others are just EditorFor(). @Html.DropDownListFor(model => model.ColorID, Model.Colors, "Select a Color") When I set the breakpoint on the db.Color.Find(...) line, I show this in the Locals window for itemmodel.Color: {System.Data.Entity.DynamicProxies.ColorModel_0EB80C07207CA5D88E1A745B3B1293D3142FE2E644A1A5202B90E5D2DAF7C2BB} When I expand that line, I can see the ColorID that I chose from the dropdown box, but it does not save into the database.

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  • How can I edit an entity in MVC4 with EF5 which has a unique constraint?

    - by Yoeri
    [HttpPost] public ActionResult Edit(Car car) { if (ModelState.IsValid) { db.Entry(car).State = EntityState.Modified; db.SaveChanges(); return RedirectToAction("Index"); } return View(car); } This is a controller method scaffolded by MCV 4 My "car" entity has a unique field: LicensePlate. I have custom validation on my Entity: Validation: public partial class Car { partial void ValidateObject(ref List<ValidationResult> validationResults) { using (var db = new GarageIncEntities()) { if (db.Cars.Any(c => c.LicensePlate.Equals(this.LicensePlate))) { validationResults.Add( new ValidationResult("This licenseplate already exists.", new string[]{"LicensePlate"})); } } } } should it be usefull, my car entity: public partial class Car:IValidatableObject { public int Id { get; set; } public string Color { get; set; } public int Weight { get; set; } public decimal Price { get; set; } public string LicensePlate { get; set; } public System.DateTime DateOfSale { get; set; } public int Type_Id { get; set; } public int Fuel_Id { get; set; } public virtual CarType Type { get; set; } public virtual Fuel Fuel { get; set; } public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) { var result = new List<ValidationResult>(); ValidateObject(ref result); return result; } partial void ValidateObject(ref List<ValidationResult> validationResults); } QUESTION: Everytime I edit a car, it raises an error: Validation failed for one or more entities. See 'EntityValidationErrors' property for more details. The error is the one raised by my validation, saying it can't edit because there is already a car with that license plate. If anyone could point me in the right direction to fix this, that would be great! I searched but couldn't find anything, so even related posts are welcome!

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  • Database storage for high sample rate data in web app

    - by Jim
    I've got multiple sensors feeding data to my web app. Each channel is 5 samples per second and the data gets uploaded bundled together in 1 minute json messages (containing 300 samples). The data will be graphed using flot at multiple zoom levels from 1 day to 1 minute. I'm using Amazon SimpleDB and I'm currently storing the data in the 1 minute chunks that I receive it in. This works well for high zoom levels, but for full days there will be simply be too many rows to retrieve. The idea I've currently got is that every hour I can crawl through the data and collect together 300 samples for the last hour and store them in an hour Domain (table if you like). Does this sound like a reasonable solution? How have others implemented the same sort of systems?

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  • Why do some languages not use semicolons and braces?

    - by Incognito
    It is interesting that some languages do not use semicolons and braces, even though their predecessors had them. Personally, it makes me nervous to write code in Python because of this. Semicolons are also missing from Google's GO language, although the lexer uses a rule to insert semicolons automatically as it scans. Why do some languages not use semicolons and braces?

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  • Adobe File Type Icons (.png)

    - by kilrizzy
    Does anybody know where i can find a list of Adobe icons? Not for the programs themselves but the recognized file types. ie: http://blogs.adobe.com/typblography/cs5icons/CS5_file_swf.png Or does anyone know where the .ico might be stored on a windows 7 machine?

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  • What are the responsibilities of the data layer?

    - by alimac83
    I'm working on a project where I had to add a data layer to my application. I've always thought that the data layer is purely responsible for CRUD functions ie. shouldn't really contain any logic but should simply retrieve data for the business layer to manipulate. However I'm a little confused with my project because I'm not sure whether I've structured my app correctly for this scenario. Basically I'm trying to retrieve a list of products from the database that fall within a certain pricing threshold. At the moment I have a function in my data layer that basically returns all products where price min threshold and price < max threshold. But it got me thinking that maybe this is incorrect. Should the data layer simply return a list of ALL products and then the business logic do the filtering? I'm pretty confused over whether the data layer should simply provide methods that allow the business layer to get raw data or whether it should be responsible for getting filtered data too? If anyone has an article or something explaining this in detail it'd be very helpful. Thanks

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  • how to pass the value in php file using Ajax.Request() function.The way i do use it's not working Wh

    - by user309381
    <html><head> function reload(form) { var val = $('seltab').getValue(); new Ajax.Request('Website.php?$cat = val', { method:'post', onSuccess: function(transport) { ..... </head> Code in PHP: echo "<select id = seltab onchange = 'reload(this.form)'>"; $querysel = "SELECT title_id,author FROM authors NATURAL JOIN books"; $result1 = mysql_query($querysel) ; while($rowID = mysql_fetch_assoc($result1)) { .... }

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