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  • Serialize JavaScript's navigator object

    - by kappa
    Hi, I'm creating a page to help diagnose the problem our users are experiencing with our web pages (you know, asking a user "What browser are you using?" usually leads to "Internet"). This page already submits to me all the HTTP headers and now I'm trying to have JavaScript give some more informations, so I thought it would be great to have the user's navigator JavaScript object and I started looking how to serialize it so I can submit it through a form. The problem is I'm not able to serialize the navigator object using any JSON library I know of, everyone returns an empty object (?!), so I decided to write an ad-hoc serializer. You can find the code here: <!DOCTYPE html> <html> <head> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.0/jquery.min.js" type="text/javascript"></script> <script type="text/javascript"> function serialize (object) { var type = typeof object; if (object === null) { return '"nullValue"'; } if (type == 'string' || type === 'number' || type === 'boolean') { return '"' + object + '"'; } else if (type === 'function') { return '"functionValue"'; } else if (type === 'object') { var output = '{'; for (var item in object) { if (item !== 'enabledPlugin') { output += '"' + item + '":' + serialize(object[item]) + ','; } } return output.replace(/\,$/, '') + '}'; } else if (type === 'undefined') { return '"undefinedError"'; } else { return '"unknownTypeError"'; } }; $(document).ready(function () { $('#navigator').text(serialize(navigator)); }); </script> <style type="text/css"> #navigator { font-family: monospaced; } </style> <title>Serialize</title> </head> <body> <h1>Serialize</h1> <p id="navigator"></p> </body> </html> This code seems to work perfectly in Firefox, Opera, Chrome and Safari but (obviously) doesn't work in Internet Explorer (at least version 8.0), it complains that "Property or method not supported by the object" at line for (var item in object) {. Do you have any hint on how to fix the code or how to reach the goal (serialize the navigator object) by other means?

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  • C#: Object having two constructors: how to limit which properties are set together?

    - by Dr. Zim
    Say you have a Price object that accepts either an (int quantity, decimal price) or a string containing "4/$3.99". Is there a way to limit which properties can be set together? Feel free to correct me in my logic below. The Test: A and B are equal to each other, but the C example should not be allowed. Thus the question How to enforce that all three parameters are not invoked as in the C example? AdPrice A = new AdPrice { priceText = "4/$3.99"}; // Valid AdPrice B = new AdPrice { qty = 4, price = 3.99m}; // Valid AdPrice C = new AdPrice { qty = 4, priceText = "2/$1.99", price = 3.99m};// Not The class: public class AdPrice { private int _qty; private decimal _price; private string _priceText; The constructors: public AdPrice () : this( qty: 0, price: 0.0m) {} // Default Constructor public AdPrice (int qty = 0, decimal price = 0.0m) { // Numbers only this.qty = qty; this.price = price; } public AdPrice (string priceText = "0/$0.00") { // String only this.priceText = priceText; } The Methods: private void SetPriceValues() { var matches = Regex.Match(_priceText, @"^\s?((?<qty>\d+)\s?/)?\s?[$]?\s?(?<price>[0-9]?\.?[0-9]?[0-9]?)"); if( matches.Success) { if (!Decimal.TryParse(matches.Groups["price"].Value, out this._price)) this._price = 0.0m; if (!Int32.TryParse(matches.Groups["qty"].Value, out this._qty)) this._qty = (this._price > 0 ? 1 : 0); else if (this._price > 0 && this._qty == 0) this._qty = 1; } } private void SetPriceString() { this._priceText = (this._qty > 1 ? this._qty.ToString() + '/' : "") + String.Format("{0:C}",this.price); } The Accessors: public int qty { get { return this._qty; } set { this._qty = value; this.SetPriceString(); } } public decimal price { get { return this._price; } set { this._price = value; this.SetPriceString(); } } public string priceText { get { return this._priceText; } set { this._priceText = value; this.SetPriceValues(); } } }

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  • What is the reason of "Transaction context in use by another session"

    - by Shrike
    Hi, I'm looking for a description of the root of this error: "Transaction context in use by another session". I get it sometimes in one of my unittests so I can't provider repro code. But I wonder what is "by design" reason for the error. I've found this post: http://blogs.msdn.com/asiatech/archive/2009/08/10/system-transaction-may-fail-in-multiple-thread-environment.aspx and also that: http://msdn.microsoft.com/en-us/library/ff649002.aspx But I can't understand what "Multiple threads sharing the same transaction in a transaction scope will cause the following exception: 'Transaction context in use by another session.' " means. All words are understandable but not the point. I actually can share a system transaction between threads. And there is even special mechanism for this - DependentTransaction class and Transaction.DependentClone method. I'm trying to reproduce a usecase from the first post: 1. Main thread creates DTC transaction, receives DependentTransaction (created using Transaction.Current.DependentClone on the main thread 2. Child thread 1 enlists in this DTC transaction by creating a transaction scope based on the dependent transaction (passed via constructor) 3. Child thread 1 opens a connection 4. Child thread 2 enlists in DTC transaction by creating a transaction scope based on the dependent transaction (passed via constructor) 5. Child thread 2 opens a connection with such code: using System; using System.Threading; using System.Transactions; using System.Data; using System.Data.SqlClient; public class Program { private static string ConnectionString = "Initial Catalog=DB;Data Source=.;User ID=user;PWD=pwd;"; public static void Main() { int MAX = 100; for(int i =0; i< MAX;i++) { using(var ctx = new TransactionScope()) { var tx = Transaction.Current; // make the transaction distributed using (SqlConnection con1 = new SqlConnection(ConnectionString)) using (SqlConnection con2 = new SqlConnection(ConnectionString)) { con1.Open(); con2.Open(); } showSysTranStatus(); DependentTransaction dtx = Transaction.Current.DependentClone(DependentCloneOption.BlockCommitUntilComplete); Thread t1 = new Thread(o => workCallback(dtx)); Thread t2 = new Thread(o => workCallback(dtx)); t1.Start(); t2.Start(); t1.Join(); t2.Join(); ctx.Complete(); } trace("root transaction completes"); } } private static void workCallback(DependentTransaction dtx) { using(var txScope1 = new TransactionScope(dtx)) { using (SqlConnection con2 = new SqlConnection(ConnectionString)) { con2.Open(); trace("connection opened"); showDbTranStatus(con2); } txScope1.Complete(); } trace("dependant tran completes"); } private static void trace(string msg) { Console.WriteLine(Thread.CurrentThread.ManagedThreadId + " : " + msg); } private static void showSysTranStatus() { string msg; if (Transaction.Current != null) msg = Transaction.Current.TransactionInformation.DistributedIdentifier.ToString(); else msg = "no sys tran"; trace( msg ); } private static void showDbTranStatus(SqlConnection con) { var cmd = con.CreateCommand(); cmd.CommandText = "SELECT 1"; var c = cmd.ExecuteScalar(); trace("@@TRANCOUNT = " + c); } } It fails on Complete's call of root TransactionScope. But error is different: Unhandled Exception: System.Transactions.TransactionInDoubtException: The transaction is in doubt. --- pired. The timeout period elapsed prior to completion of the operation or the server is not responding. To sum up: I want to understand what "Transaction context in use by another session" means and how to reproduce it.

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  • facebook open graph meta property og:type of 'website'. The property 'object-name' requires an object of og:type 'object-name'

    - by chinmayahd
    in cake php 1.3 in view ctp i have follow code: $url = 'http://example.com/exmp/explus/books/view/'.$book['Book']['id']; echo $this->Html->meta(array('property' => 'fb:app_id', 'content' => '*******'),'',array('inline'=>false)); echo $this->Html->meta(array('property' => 'og:type', 'content' => 'book'),'',array('inline'=>false)); echo $this->Html->meta(array('property' => 'og:url', 'content' => $url ),'',array('inline'=>false)); echo $this->Html->meta(array('property' => 'og:title', 'content' => $book['Book']['title']),'',array('inline'=>false)); echo $this->Html->meta(array('property' => 'og:description', 'content' => $book['Book']['title']),'',array('inline'=>false)); $imgurl = '../image/'.$book['Book']['id']; echo $this->Html->meta(array('property' => 'og:image', 'content' => $imgurl ),'',array('inline'=>false)); ?> and it gives the following error when i am posting it' { "error": { "message": "(#3502) Object at URL http://example.com/exmp/explus/books/view/234' has og:type of 'website'. The property 'book' requires an object of og:type 'book'. ", "type": "OAuthException", "code": 3502 } } is any one know how to solve it?

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  • Web workflow solution - how should I approach the design?

    - by Tom Pickles
    We've been tasked with creating a web based workflow tool to track change management. It has a single workflow with multiple synchronous tasks for the most part, but branch out at a point to tasks running in parallel which meet up later on. There will be all sorts of people using the application, and all of them will need to see their outstanding tasks for each change, but only theirs, not others. There will also be a high level group of people who oversee all changes, so need to see everything. They will need to see tasks which have not been done in the specified time, who's responsible etc. The data will be persisted to a SQL database. It'll all be put together using .Net. I've been trying to learn and implement OOP into my designs of late, but I'm wondering if this is moot in this instance as it may be better to have the business logic for this in stored procedures in the DB. I could use POCO's, a front end layer and a data access layer for the web application and just use it as a mechanism for CRUD actions on the DB, then use SP's fired in the DB to apply the business rules. On the other hand, I could use an object oriented design within the web app, but as the data in the app is state-less, is this a bad idea? I could try and model out the whole application into a class structure, implementing interfaces, base classes and all that good stuff. So I would create a change class, which contained a list of task classes/types, which defined each task, and implement an ITask interface etc. Put end-user types into the tasks to identify who should be doing what task. Then apply all the business logic in the respective class methods etc. What approach do you guys think I should be using for this solution?

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  • When too much encapsulation was reached

    - by Samuel
    Recently, I read a lot of gook articles about how to do a good encapsulation. And when I say "good encapsulation", I don't talk about hiding private fields with public properties; I talk about preventing users of your Api to do wrong things. Here is two good articles about this subject: http://blog.ploeh.dk/2011/05/24/PokayokeDesignFromSmellToFragrance.aspx http://lostechies.com/derickbailey/2011/03/28/encapsulation-youre-doing-it-wrong/ At my job, the majority a our applications are not destined to other programmers but rather to the customers. About 80% of the application code is at the top of the structure (Not used by other code). For this reason, there is probably no chance ever that this code will be used by other application. An example of encapsulation that prevent user to do wrong thing with your Api is to return an IEnumerable instead of IList when you don't want to give the ability to the user to add or remove items in the list. My question is: When encapsulation could be considered like too much of purism object oriented programming while keeping in mind that each hour of programming is charged to the customer? I want to do good code that is maintainable, easy to read and to use but when this is not a public Api (Used by other programmer), where could we put the line between perfect code and not so perfect code? Thank you.

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  • AsyncTask and Contexts

    - by Michael
    So I'm working out my first multi-threaded application using Android with the AsyncTask class. I'm trying to use it to fire off a Geocoder in a second thread, then update the UI with onPostExecute, but I keep running into an issue with the proper Context. I kind of hobbled my way through using Contexts on the main thread, but I'm not exactly sure what the Context is or how to use it on background threads, and I haven't found any good examples on it. Any help? Here is an excerpt of what I'm trying to do: public class GeoCode extends AsyncTask<GeoThread, Void, GeoThread> { @Override protected GeoThread doInBackground(GeoThread... i) { List<Address> addresses = null; Geocoder geoCode = null; geoCode = new Geocoder(null); //Expects at minimum Geocoder(Context context); addresses = geoCode.getFromLocation(GoldenHour.lat, GoldenHour.lng, 1); } } It keeps failing at the sixth line there, because of the improper Context.

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  • Entity Framework with ASP.NET MVC. Updating entity problem

    - by Kitaly
    Hi people. I'm trying to update an entity and its related entities as well. For instance, I have a class Car with a property Category and I want to change its Category. So, I have the following methods in the Controller: public ActionResult Edit(int id) { var categories = context.Categories.ToList(); ViewData["categories"] = new SelectList(categories, "Id", "Name"); var car = context.Cars.Where(c => c.Id == id).First(); return PartialView("Form", car); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(Car car) { var category = context.Categories.Where(c => c.Id == car.Category.Id).First(); car.Category = category; context.UpdateCar(car); context.SaveChanges(); return RedirectToAction("Index"); } The UpdateCar method, in ObjectContext class, follows: public void UpdateCar(Car car) { var attachedCar = Cars.Where(c => c.Id == car.Id).First(); ApplyItemUpdates(attachedCar, car); } private void ApplyItemUpdates(EntityObject originalItem, EntityObject updatedItem) { try { ApplyPropertyChanges(originalItem.EntityKey.EntitySetName, updatedItem); ApplyReferencePropertyChanges(updatedItem, originalItem); } catch (InvalidOperationException ex) { Console.WriteLine(ex.ToString()); } } public void ApplyReferencePropertyChanges(IEntityWithRelationships newEntity, IEntityWithRelationships oldEntity) { foreach (var relatedEnd in oldEntity.RelationshipManager.GetAllRelatedEnds()) { var oldRef = relatedEnd as EntityReference; if (oldRef != null) { var newRef = newEntity.RelationshipManager.GetRelatedEnd(oldRef.RelationshipName, oldRef.TargetRoleName) as EntityReference; oldRef.EntityKey = newRef.EntityKey; } } } The problem is that when I set the Category property after the POST in my controller, the entity state changes to Added instead of remaining as Detached. How can I update one-to-one relationship with Entity Framework and ASP.NET MVC without setting all the properties, one by one like this post?

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  • HttpModule to Write Out JavaScript Script References to the Response

    - by Chris
    On my page in the Page_Load event I add a collection of strings to the Context object. I have an HttpModule that will fire EndRequest and retrieve the collection of strings. What I then do is write out a script reference tag (based on the collection of strings) to the response. The problem is that the page reads the script reference but doesn't retrieve the contents of the file (I imagine because this is occurring in the EndRequest event). I can't fire the BeginRequest event because I won't have access to the Context Items collection. I tried to also registering an HttpHandler which Processes the request of the script reference but I can't access the collection of strings in the Context.Items from there. Any suggestions? Page_Load: protected void Page_Load(object sender, EventArgs e) { Context.Items.Add("ScriptFile", "/UserControls.js"); } HttpModule: public void OnEndRequest(Object s, EventArgs e) { HttpApplication app = s as HttpApplication; object script = app.Context.Items["ScriptFile"]; app.Response.Write("<script type='text/javascript' src='" + script + "'></script>"); }

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  • Manager/Container class vs static class methods

    - by Ben
    Suppose I a have a Widget class that is part of a framework used independently by many applications. I create Widget instances in many situations and their lifetimes vary. In addition to Widget's instance specified methods, I would like to be able to perform the follow class wide operations: Find a single Widget instance based on a unique id Iterate over the list of all Widgets Remove a widget from the set of all widgets In order support these operations, I have been considering two approaches: Container class - Create some container or manager class, WidgetContainer, which holds a list of all Widget instances, support iteration and provides methods for Widget addition, removal and lookup. For example in C#: public class WidgetContainer : IEnumerable<Widget { public void AddWidget(Widget); public Widget GetWidget(WidgetId id); public void RemoveWidget(WidgetId id); } Static class methods - Add static class methods to Widget. For example: public class Widget { public Widget(WidgetId id); public static Widget GetWidget(WidgetId id); public static void RemoveWidget(WidgetId id); public static IEnumerable<Widget AllWidgets(); } Using a container class has the added problem of how to access the container class. Make it a singleton?..yuck! Create some World object that provides access to all such container classes? I have seen many frameworks that use the container class approach, so what is the general consensus?

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  • Is comparing an OO compiler to a SQL compiler/optimizer valid?

    - by Brad
    I'm now doing a lot of SQL development at my new job where as before I was doing Object Oriented desktop app stuff. I keep running across very large scripts (thousands of lines) and wanting to refactor in some way. I am seeing that SQL is a different sort of beast and it's probably fine to have these big scripts for the most part but while explaining this to me people are also insisting that the whole idea of refactoring is bad. That stuff like the .NET compiler are actually burdened by refactored code and that a big wall of code is more efficient and better design than code designed for reuse, readability and scalability. The other argument is that OO compilers are almost dangerously inefficient and don't have efficient memory management or runs too many CPU instructions compared to older "simpler" compilers and compared to SQL. Are these valid complaints? Even if some compiler like a C compiler is modestly more "efficient" (whatever that means on this high of a level without seeing code) would you want to write applications in C over C# or Java? Is comparing an OO compiler to a SQL compiler/optimizer even valid?

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  • Getting rid of Massive View Controller in iOS?

    - by Earl Grey
    I had a discussion with my colleague about the following problem. We have an application where we need filtering functionality. On any main screen within the upper navigation bar, there is a button in the upper right corner. Once you touch that button, an custom written Alert View like view will pop up modally, behind it a semitransparent black overlay view. In that modal view, there is a table view of options, and you can choose one exclusively. Based on your selection, once this modal view is closed, the list of items in the main view is filtered. It is simply a modally presented filter to filter the main table view.This UI design is dictated by the design department, I cannot do anything about it so let accept this as a premise. Also the main filter button in the navbar will change colours to indicate that the filter is active. The question I have is about implementation. I suggested to my colleague that we create a separate XYZFilter class that will be an instance created by the main view controller acquire the filtering options handle saving and restoration of its state - i.e. last filter selected provide its two views - the overlay view and the modal view be the datasource for the table in its modal view. For some unknown reason, my colleague was not impressed by that approach at all. He simply wants to do these functionalities in the main view controller, maybe out of being used to do this in the past like that :-/ Is there any fundamental problem with my approach? I want to keep the view controller small, not to have spaghetti code create a reusable component (for use outside the project) have more object oriented, decoupled approach. prevent duplication of code as we need the filtering in two different places but it looks the same in both.. Any advice?

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  • Architectural Composition Languages

    - by C. Lawrence Wenham
    Recently stumbled upon this paper (PDF) talking about ACLs, or Architectural Composition Languages. They're a fusion of two earlier lines of research: Architectural Definition Languages (such as UML) and Object Composition Languages (such as XAML, WWF, or scripting languages). The goal of an ACL is to have a high-level description of a program's architecture which can also be compiled into a runnable program. The high-level description assists automated analysis, while the 'executability' means changes can be tested immediately. You would still author the components of the program in a conventional programming language (C, Java, Python, etc), but they would be composed into a complete program by the ACL. One of the expected benefits is that a program can be ported to a different platform by swapping in "similar but different" components. I've been hankering for something like this for a long time (see this answer I gave on a StackOverflow question a few years ago). The paper mentions that the researchers were working on a language called ACL/1 that initially targeted Java, but would be ported to support .Net as well. However, I can't find any more mention of ACL/1 anywhere. Has there been any more work done on this? Are there any other implementations of the ACL concept that are available for use or experimentation?

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  • What is the ideal length of a method?

    - by iPhoneDeveloper
    In object-oriented programming, there is no exact rule on the maximum length of a method , but I still found these two qutes somewhat contradicting each other, so I would like to hear what you think. In Clean Code: A Handbook of Agile Software Craftsmanship, Robert Martin says: The first rule of functions is that they should be small. The second rule of functions is that they should be smaller than that. Functions should not be 100 lines long. Functions should hardly ever be 20 lines long. and he gives an example from Java code he sees from Kent Beck: Every function in his program was just two, or three, or four lines long. Each was transparently obvious. Each told a story. And each led you to the next in a compelling order. That’s how short your functions should be! This sounds great, but on the other hand, in Code Complete, Steve McConnell says something very different: The routine should be allowed to grow organically up to 100-200 lines, decades of evidence say that routines of such length no more error prone then shorter routines. And he gives a reference to a study that says routines 65 lines or long are cheaper to develop. So while there are diverging opinions about the matter, is there a functional best-practice towards determining the ideal length of a method for you?

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  • How to drastically improve code coverage?

    - by Peter Kofler
    I'm tasked with getting a legacy application under unit test. First some background about the application: It's a 600k LOC Java RCP code base with these major problems massive code duplication no encapsulation, most private data is accessible from outside, some of the business data also made singletons so it's not just changeable from outside but also from everywhere. no business model, business data is stored in Object[] and double[][], so no OO. There is a good regression test suite and an efficient QA team is testing and finding bugs. I know the techniques how to get it under test from classic books, e.g. Michael Feathers, but that's too slow. As there is a working regression test system I'm not afraid to aggressively refactor the system to allow unit tests to be written. How should I start to attack the problem to get some coverage quickly, so I'm able to show progress to management (and in fact to start earning from safety net of JUnit tests)? I do not want to employ tools to generate regression test suites, e.g. AgitarOne, because these tests do not test if something is correct.

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  • How would I set up this enum to return the image I want?

    - by Justen
    I'm trying to set up this enum so that it has the ability to return the correct image, though I'm struggling with a way to incorporate the context since it is in a separate class. public enum CubeType { GREEN { public Drawable getImage() { return Context.getResources().getDrawable( R.drawable.cube_green ); } }; abstract public Drawable getImage(); } The error I'm getting is: Cannot make a static reference to the non-static method getResources() from the type Context

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  • Teaching OO to VBA developers [closed]

    - by Eugene
    I work with several developers that come from less object oriented background like (VB6, VBA) and are mostly self-taught. As part of moving away from those technologies we recently we started having weekly workshops to go over the features of C#.NET and OO practices and design principles. After a couple of weeks of basic introduction I noticed that they had a lot of problems implementing even basic code. For instance it took probably 15 minutes to implement a Stack.push() and a full hour to implement a simple Stack fully. These developers were trying to do things like passing top index as a parameter to the method, not creating an private array, using variables out of scope. But most of all not going through the "design (dia/mono)log" (I need something to do X, so maybe I'll make an array, or put it here). I am a little confused because they are smart people and are able to produce functional code in their traditional environments. I'm curious if anybody else has encountered a similar thing and if there are any particular resources, exercises, books, ideas that would be helpful in this circumstance.

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  • Is creating a separate pool for each individual image created from a png appropriate?

    - by Panzercrisis
    I'm still possibly a little green about object-pooling, and I want to make sure something like this is a sound design pattern before really embarking upon it. Take the following code (which uses the Starling framework in ActionScript 3): [Embed(source = "/../assets/images/game/misc/red_door.png")] private const RED_DOOR:Class; private const RED_DOOR_TEXTURE:Texture = Texture.fromBitmap(new RED_DOOR()); private const m_vRedDoorPool:Vector.<Image> = new Vector.<Image>(50, true); . . . public function produceRedDoor():Image { // get a Red Door image } public function retireRedDoor(pImage:Image):void { // retire a Red Door Image } Except that there are four colors: red, green, blue, and yellow. So now we have a separate pool for each color, a separate produce function for each color, and a separate retire function for each color. Additionally there are several items in the game that follow this 4-color pattern, so for each of them, we have four pools, four produce functions, and four retire functions. There are more colors involved in the images themselves than just their predominant one, so trying to throw all the doors, for instance, in a single pool, and then changing their color properties around isn't going to work. Also the nonexistence of the static keyword is due to its slowness in AS3. Is this the right way to do things?

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  • Is creating a separate pool for each individual png image in the same class appropriate?

    - by Panzercrisis
    I'm still possibly a little green about object-pooling, and I want to make sure something like this is a sound design pattern before really embarking upon it. Take the following code (which uses the Starling framework in ActionScript 3): [Embed(source = "/../assets/images/game/misc/red_door.png")] private const RED_DOOR:Class; private const RED_DOOR_TEXTURE:Texture = Texture.fromBitmap(new RED_DOOR()); private const m_vRedDoorPool:Vector.<Image> = new Vector.<Image>(50, true); . . . public function produceRedDoor():Image { // get a Red Door image } public function retireRedDoor(pImage:Image):void { // retire a Red Door Image } Except that there are four colors: red, green, blue, and yellow. So now we have a separate pool for each color, a separate produce function for each color, and a separate retire function for each color. Additionally there are several items in the game that follow this 4-color pattern, so for each of them, we have four pools, four produce functions, and four retire functions. There are more colors involved in the images themselves than just their predominant one, so trying to throw all the doors, for instance, in a single pool, and then changing their color properties around isn't going to work. Also the nonexistence of the static keyword is due to its slowness in AS3. Is this the right way to do things?

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  • Do you leverage the benefits of the open-closed principle?

    - by Kaleb Pederson
    The open-closed principle (OCP) states that an object should be open for extension but closed for modification. I believe I understand it and use it in conjunction with SRP to create classes that do only one thing. And, I try to create many small methods that make it possible to extract out all the behavior controls into methods that may be extended or overridden in some subclass. Thus, I end up with classes that have many extension points, be it through: dependency injection and composition, events, delegation, etc. Consider the following a simple, extendable class: class PaycheckCalculator { // ... protected decimal GetOvertimeFactor() { return 2.0M; } } Now say, for example, that the OvertimeFactor changes to 1.5. Since the above class was designed to be extended, I can easily subclass and return a different OvertimeFactor. But... despite the class being designed for extension and adhering to OCP, I'll modify the single method in question, rather than subclassing and overridding the method in question and then re-wiring my objects in my IoC container. As a result I've violated part of what OCP attempts to accomplish. It feels like I'm just being lazy because the above is a bit easier. Am I misunderstanding OCP? Should I really be doing something different? Do you leverage the benefits of OCP differently? Update: based on the answers it looks like this contrived example is a poor one for a number of different reasons. The main intent of the example was to demonstrate that the class was designed to be extended by providing methods that when overridden would alter the behavior of public methods without the need for changing internal or private code. Still, I definitely misunderstood OCP.

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  • What type of pattern would be used in this case

    - by Admiral Kunkka
    I want to know how to tackle this type of scenario. We are building a person's background, from scratch, and I want to know, conceptually, how to proceed with a secure object pattern in both design and execution... I've been reading on Factory patterns, Model-View-Controller types, Dependency injection, Singleton approaches... and I can't seem to grasp or 'fit' these types of designs decisions into what I'm trying to do.. First and foremost, I started with having a big jack-of-all-trades class, then I read some more, and some tips were to make sure your classes only have a single purpose.. which makes sense and I started breaking down certain things into other classes. Okay, cool. Now I'm looking at dependency injection and kind of didn't really know what's going on. Example/insight of what kind of heirarchy I need to accomplish... class Person needs to access and build from a multitude of different classes. class Culture needs to access a sub-class for culture benefits class Social needs to access class Culture, and other sub-classes class Birth needs to access Social, Culture, and other sub-classes class Childhood/Adolescence/Adulthood need to access everything. Also, depending on different rolls, this class heirarchy needs to create multiple people as well, such as Family, and their backgrounds using some, if not all, of these same classes. Think of it as a people generator, all random, with backgrounds and things that happen to them. Ageing, death of loved ones, military careers, e.t.c. Most of the generation is done randomly, making calls to a mt_rand function to pick from most of the selections inside the classes, guaranteeing the data to be absolutely random. I have most of the bulk-data down, and was looking for some insight from fellow programmers, what do you think?

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  • Do objects maintain identity under all non-cloning conditions in PHP?

    - by Buttle Butkus
    PHP 5.5 I'm doing a bunch of passing around of objects with the assumption that they will all maintain their identities - that any changes made to their states from inside other objects' methods will continue to hold true afterwards. Am I assuming correctly? I will give my basic structure here. class builder { protected $foo_ids = array(); // set in construct protected $foo_collection; protected $bar_ids = array(); // set in construct protected $bar_collection; protected function initFoos() { $this->foo_collection = new FooCollection(); foreach($this->food_ids as $id) { $this->foo_collection->addFoo(new foo($id)); } } protected function initBars() { // same idea as initFoos } protected function wireFoosAndBars(fooCollection $foos, barCollection $bars) { // arguments are passed in using $this->foo_collection and $this->bar_collection foreach($foos as $foo_obj) { // (foo_collection implements IteratorAggregate) $bar_ids = $foo_obj->getAssociatedBarIds(); if(!empty($bar_ids) ) { $bar_collection = new barCollection(); // sub-collection to be a component of each foo foreach($bar_ids as $bar_id) { $bar_collection->addBar(new bar($bar_id)); } $foo_obj->addBarCollection($bar_collection); // now each foo_obj has a collection of bar objects, each of which is also in the main collection. Are they the same objects? } } } } What has me worried is that foreach supposedly works on a copy of its arrays. I want all the $foo and $bar objects to maintain their identities no matter which $collection object they become of a part of. Does that make sense?

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  • Are there design patterns or generalised approaches for particle simulations?

    - by romeovs
    I'm working on a project (for college) in C++. The goal is to write a program that can more or less simulate a beam of particles flying trough the LHC synchrotron. Not wanting to rush into things, me and my team are thinking about how to implement this and I was wondering if there are general design patterns that are used to solve this kind of problem. The general approach we came up with so far is the following: there is a World that holds all objects you can add objects to this world such as Particle, Dipole and Quadrupole time is cut up into discrete steps, and at each point in time, for each Particle the magnetic and electric forces that each object in the World generates are calculated and summed up (luckily electro-magnetism is linear). each Particle moves accordingly (using a simple estimation approach to solve the differential movement equations) save the Particle positions repeat This seems a good approach but, for instance, it is hard to take into account symmetries that might be present (such as the magnetic field of each Quadrupole) and is this thus suboptimal. To take into account such symmetries as that of the Quadrupole field, it would be much easier to (also) make space discrete and somehow store form of the Quadrupole field somewhere. (Since 2532 or so Quadrupoles are stored this should lead to a massive gain of performance, not having to recalculate each Quadrupole field) So, are there any design patterns? Is the World-approach feasible or is it old-fashioned, bad programming? What about symmetry, how is that generally taken into acount?

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  • How to store a list of Objects that might change in future?

    - by Amogh Talpallikar
    I have set of Objects of the same class which have different values of their attributes. and I need to find the best match from a function under given scenarios out of these objects. In future these objects might increase as well. Quite similar to the way we have Color class in awt. we have some static color objects in the class with diff rgb values. But in my case say, I need to chose the suitable color out of these static ones based on certain criteria. So should I keep them in an arrayList or enum or keep them as static vars as in case of Colors. because I will need to parse through all of them and decide upon the best match. so I need them in some sort of collection. But in future if I need to add another type I will have to modify the class and add another list.add(object) call for this one and then it will violate the open-close principle. How should I go about it ?

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