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• Why would ASP.NET MVC use session state?

  - by ray247

  Recommended by the ASP.NET team to use cache instead of session, we stopped using session from working with the WebForm model the last few years. So we normally have the session turned off in the web.config <sessionState mode="Off" /> But, now when I'm testing out a ASP.NET MVC application with this setting it throw an error in class SessionStateTempDataProvider inside the mvc framework, it asked me to turn on session state, I did and it worked. Looking at the source it uses session Dictionary<string, object> tempDataDictionary = httpContext.Session[TempDataSessionStateKey] as Dictionary<string, object>; // line 20 in SessionStateTempDataProvider.cs So, why would they use session here? What am I missing? Thanks, Ray. ======================================================== Edit Sorry didn't mean for this post to debate on session vs. cache, but rather in the context of the ASP.NET MVC, I was just wondering why session is used here. In this Scott Watermasysk blog post he mentioned on turning off session too as a good practice, so I'm just wondering do I have to turn it on to use MVC from here on?

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• using dummy row with NOT NULL to solve DEFAULT NULL

  - by Tony38

  I know having DEFAULT NULLS is not a good practice but I have many optional lookup values which are FK in the system so to solve this issue here is what i am doing: I use NOT NULL for every FK / lookup colunms. I have the first row in every lookup table which is PK id = 1 as a dummy row with just "none" in all the columns. This way I can use NOT NULL in my schema and if needed reference to the none row values PK =1 for FKs which do not have any lookup value. Is this a good design or any other work arounds? EDIT: I have: Neighborhood table Postal table. Every neighborhood has a city, so the FK can be NOT NULL. But not every postal code belongs to a neighborhood. Some do, some don't depending on the country. So if i use NOT NULL for the FK between postal and neighborhood then I will be screwed as there has to be some value entered. So what i am doing in essence is: have a row in every table to be a dummy row just to link the FKs. This way row one in neighborhood table will be: n_id = 1 name =none etc... In postal table I can have: postal_code = 3456A3 FK (city) = Moscow FK (neighborhood_id)=1 as a NOT NULL. If I don't have a dummy row in the neighborhood lookup table then I have to declare FK (neighborhood_id) as a Default null column and store blanks in the table. This is an example but there is a huge number of values which will have blanks then in many tables.

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• Old dll.config problem !

  - by user313421

  Since 2005 as I googled it's a problem for who needs to read the configuration of an assembly from it's config file "*.dll.config" and Microsoft didn't do anything yet. Story: If you try to read a setting from a class library (plug-in) you fail. Instead the main application domain (EXE which is using the plug-in) config is read and because probably there's not such a config your plug-in will use default setting which is hard-coded when you create it's settings for first time. Any change to .dll.config wouldn't see by your plug-in and you wonder why it's there! If you want to replace it and start searching you may find something like this: http://stackoverflow.com/questions/594298/c-dll-config-file But just some ideas and one line code. A good replacement for built-in config shouldn't read from file system each time we need a config value, so we can store them in memory; Then what if user changes config file ? we need a FileSystemWatcher and we need some design like singleton ... and finally we are at the same point configuration of .NET is except our one's working. It seems MS did everything but forgot why they built the ".dll.config". Since no DLL is gonna execute by itself, they are referenced from other apps (even if used in web) and so why there's such a "*.dll.config" file ? I'm not gonna argue if it's good to have multiple config files or not. It's my design (plug-able components). Finally { After these years, is there any good practice such as a custom setting class to add in each assemly and read from it's own config file ? }

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• What is wrong with locking non-static fields? What is the correct way to lock a particular instance?

  - by smartcaveman

  Why is it considered bad practice to lock non-static fields? And, if I am not locking non-static fields, then how do I lock an instance method without locking the method on all other instances of the same or derived class? I wrote an example to make my question more clear. public abstract class BaseClass { private readonly object NonStaticLockObject = new object(); private static readonly object StaticLockObject = new object(); protected void DoThreadSafeAction<T>(Action<T> action) where T: BaseClass { var derived = this as T; if(derived == null) { throw new Exception(); } lock(NonStaticLockObject) { action(derived); } } } public class DerivedClass :BaseClass { private readonly Queue<object> _queue; public void Enqueue(object obj) { DoThreadSafeAction<DerivedClass>(x=>x._queue.Enqueue(obj)); } } If I make the lock on the StaticLockObject, then the DoThreadSafeAction method will be locked for all instances of all classes that derive from BaseClass and that is not what I want. I want to make sure that no other threads can call a method on a particular instance of an object while it is locked.

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• iPhone SDK math - pythagorean theorem problem!

  - by Flafla2

  Just as a practice, I am working on an app that solves the famous middle school pythagorean theorem, a squared + b squared = c squared. Unfortunately, the out-coming answer has, in my eyes, nothing to do with the actual answer. Here is the code used during the "solve" action. - (IBAction)solve { int legoneint; int legtwoint; int hypotenuseint; int lonesq = legoneint * legoneint; int ltwosq = legtwoint * legtwoint; int hyposq = hypotenuseint * hypotenuseint; hyposq = lonesq + ltwosq; if ([legone.text isEqual:@""]) { legtwoint = [legtwo.text intValue]; hypotenuseint = [hypotenuse.text intValue]; answer.text = [NSString stringWithFormat:@"%d", legoneint]; self.view.backgroundColor = [UIColor blackColor]; } if ([legtwo.text isEqual:@""]) { legoneint = [legone.text intValue]; hypotenuseint = [hypotenuse.text intValue]; answer.text = [NSString stringWithFormat:@"%d", legtwoint]; self.view.backgroundColor = [UIColor blackColor]; } if ([hypotenuse.text isEqual:@""]) { legoneint = [legone.text intValue]; legtwoint = [legtwo.text intValue]; answer.text = [NSString stringWithFormat:@"%d", hypotenuseint]; self.view.backgroundColor = [UIColor blackColor]; } } By the way, legone, legtwo, and hypotenuse all represent the UITextField that corresponds to each mathematical part of the right triangle. Answer is the UILabel that tells, you guessed it, the answer. Does anyone see any flaws in the program? Thanks in advance!

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• Does cout need to be terminated with a semicolon ?

  - by Philippe Harewood

  I am reading Bjarne Stroustrup's Programming : Principles and Practice Using C++ In the drill section for Chapter 2 it talks about various ways to look at typing errors when compiling the hello_world program #include "std_lib_facilities.h" int main() //C++ programs start by executing the function main { cout << "Hello, World!\n", // output "Hello, World!" keep_window_open(); // wait for a character to be entered return 0; } In particular this section asks: Think of at least five more errors you might have made typing in your program (e.g. forget keep_window_open(), leave the Caps Lock key on while typing a word, or type a comma instead of a semicolon) and try each to see what happens when you try to compile and run those versions. For the cout line, you can see that there is a comma instead of a semicolon. This compiles and runs (for me). Is it making an assumption ( like in the javascript question: Why use semicolon? ) that the statement has been terminated ? Because when I try for keep_terminal_open(); the compiler informs me of the semicolon exclusion.

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• Which languages and techniques can I use to improve my coding practices?

  - by Danjah

  I've been offered the opportunity upskill through study, while at work which is great. My background I am mostly self-taught, but have worked with many excellent people over the years - both self-taught and fully educated, and on many decent projects. I have mild experience in Actionscript, I'm getting better every day with my Javascript, and my CSS is angled at best practice, but needs a bit of modernising. I'm a traditional interface developer, I'm not stupid and I like a challenge. My goal I need to start seeing ways of applying better logic, optimising code, refactoring, different styles of development (agile, others?), and.. well I need to try and start thinking like.. a more solid programmer. Its hard to describe, I have good solutions and I'm efficient - but I KNOW that there's a bunch I am missing. I am already employed with a solid career, but I feel the need to fill gaps. My question/s Are there a set of guiding principles you can recommend I focus on to improve the points above? Are there particular programming languages which I might focus on to get a broader overview? Do you think I should avoid particular styles of development, or even languages, while solidifying what might end up being part 'the basics' but hopefully 'advanced programming'? -- Sorry if this appears off topic or something but I figure you're probably some of the best people to ask.

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• Which Stroustrup book should I use?

  - by Chris Simmons

  I'm a C# programmer that is looking to branch out. I'm bored of writing business software and want to start getting into graphics programming and games/simulators. So I figured, although writing that stuff isn't impossible in managed code, the "right" way to do that would be to look to C++, of course focussing on the language first, then getting into OpenGL or DirectX (or whatever). Way way back ('98? '99?) I had tried and failed to really grasp Stroustrup's The C++ Programming Language. I know that this book is often not recommended for the beginner. Anyway, I picked it back up (in a much more recent printing) and I'm actually getting it and enjoying it. I also have a copy of his textbook, Programming: Principles and Practice Using C++, which, as I understand it, is really geared toward teaching programming, not necessarily C++. I'm certainly not arrogant enough to claim I don't have anything more to learn about programming, data structures, algoriths, etc., however I'm not a novice there either. So my question is, with the goal of gaining the broader and more real-world-useful understanding of C++ and given my background, on which should I focus? The denser (as I perceive it) TCPPPL or the gentler Programming? EDIT: I thank everyone for the responses. However, I've got a personal choice here to make between these two books. Granted there are other very good books out there, but I'm already a good length into both of the books I mention and I'd like to finish one. So, can anyone respond on which would be the better and why? Time is not an issue; I'm not looking (at this point) at an "accelerated" read.

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• How to map combinations of things to a relational database?

  - by Space_C0wb0y

  I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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• My chance to shape our development process/policy

  - by Matt Luongo

  Hey guys, I'm sorry if this is a duplicate, but the question search terms are pretty generic. I work at a small(ish) development firm. I say small, but the company is actually a fair size; however, I'm only the second full-time developer, as most past work has been organized around contractors. I'm in a position to define internal project process and policy- obvious stuff like SCM and unit-testing. Methodology is outside the scope of the document I'm putting together, but I'd really like to push us in a leaner (and maybe even Agile?) direction. I feel like I have plenty of good practice recommendations, but not enough solid motivation to make my document the spirit guide I'd like it to be. I've separated the document into "principles" and "recommendations". Recommendations have been easy to come up with. Use SCM, strive for 1-step, regularly scheduled builds, unit test first, document as you go... Listing the principles that are supposed to be informing these recommendations, though, has been rough. I've come up with "tools work for us; we should never work for tools" and a hazy clause aimed at our QA (which has been overly manual) that I'd like to read "tedium is the root of all evil". I don't want to miss an opportunity with this document to give us a good in-house start and maybe even push us toward Agile. What principles am I missing?

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• Advice on whether to use native C++ DLL or not: PINVOKE & Marshaling ?

  - by Bob

  What's the best way to do this....? I have some Native C++ code that uses a lot of Win32 calls together with byte buffers (allocated using HeapAlloc). I'd like to extend the code and make a C# GUI...and maybe later use a basic Win32 GUI (for use where there is no .Net and limited MFC support). (A) I could just re-write the code in C# and use multiple PINVOKEs....but even with the PINVOKES in a separate class, the code looks messy with all the marshaling. I'm also re-writing a lot of code. (B) I could create a native C++ DLL and use PINVOKE to marshal in the native data structures. I'm assuming I can include the native C++ DLL/LIB in a project using C#? (C) Create a mixed mode DLL (Native C++ class plus managed ref class). I'm assuming that this would make it easier to use the managed ref class in C#......but is this the case? Will the managed class handle all the marshaling? Can I use this mixed mode DLL on a platform with no .Net (i.e. still access the native C++ unmanaged component) or do I limit myself to .Net only platforms. One thing that bothers me about each of these options is all the marshalling. Is it better to create a managed data structure (array, string etc.) and pass that to the native C++ class, or, the other way around? Any ideas on what would be considered best practice...?

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• What algorithms compute directions from point A to point B on a map?

  - by A. Rex

  How do map providers (such as Google or Yahoo! Maps) suggest directions? I mean, they probably have real-world data in some form, certainly including distances but also perhaps things like driving speeds, presence of sidewalks, train schedules, etc. But suppose the data were in a simpler format, say a very large directed graph with edge weights reflecting distances. I want to be able to quickly compute directions from one arbitrary point to another. Sometimes these points will be close together (within one city) while sometimes they will be far apart (cross-country). Graph algorithms like Dijkstra's algorithm will not work because the graph is enormous. Luckily, heuristic algorithms like A* will probably work. However, our data is very structured, and perhaps some kind of tiered approach might work? (For example, store precomputed directions between certain "key" points far apart, as well as some local directions. Then directions for two far-away points will involve local directions to a key points, global directions to another key point, and then local directions again.) What algorithms are actually used in practice? PS. This question was motivated by finding quirks in online mapping directions. Contrary to the triangle inequality, sometimes Google Maps thinks that X-Z takes longer and is farther than using an intermediate point as in X-Y-Z. But maybe their walking directions optimize for another parameter, too? PPS. Here's another violation of the triangle inequality that suggests (to me) that they use some kind of tiered approach: X-Z versus X-Y-Z. The former seems to use prominent Boulevard de Sebastopol even though it's slightly out of the way. (Edit: this example doesn't work anymore, but did at the time of the original post. The one above still works as of early November 2009.)

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• How to embed a precharged collection of non-entity forms in symfony2

  - by metalvarez

  I want to embed a collection of precharged non-entity forms, here is the code, first is the parent form buildForm method. public function buildForm(FormBuilderInterface $builder, array $options) { $builder->add("example1")->add("example2"); $builder->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) { /*some logic to do before adding the collection of forms*/ $form->add('aclAccess', 'collection', array( 'type' => new ChildFormType(), 'allow_add' => true, 'mapped' => false, 'data' => /* I dont know how to precharge a collection of non-entity forms*/ )); }); } now the child form public function buildForm (FormBuilderInterface $builder, array $options) { $builder->add("test1", "text", array("read_only" => true, "data" => "test")); $builder->->add("test2", "choice", array( 'choices' => array('opt1' => 'Opt1', 'opt2' => 'Opt2'), 'multiple' => true, 'expanded' => true )); } so basicly i want to manage those child options in the test2 field as separated forms, each option group will depend on the value of the test1 field, i know this can be done by coding everythin in twig without form classes but i think having form classes its the best practice to run phpunit test, for maintainability, etc ...

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• Understanding Hibernate saveOrUpdate and the Persistence Life Cycle

  - by Stephano

  The books that I've read regarding hibernate are, at best, reference tomes. They very seldom have good code examples, so I tend to use online resources for those needs. However, I've always had a problem understanding the basic idea of hibernate persistence. I've read the books and understand the concepts, but in practice, I often see results that I don't understand. Perhaps you all can help, as you have in the past. Let's look at a simple example of a dog and a cat that are friends. This isn't a rare occurrence. It also has the benefit of being much more interesting than my business case. We want a function called "saveFriends" that takes a dog name and a cat name. We'll save the Dog and then the Cat. For this example to work, the cat is going to have a reference back to the dog. I understand this isn't an ideal example, but it's cute and works for our purposes. FriendService.java public int saveFriends(String dogName, String catName) { Dog fido = new Dog(); Cat felix = new Cat(); fido.name = dogName; fido = animalDao.saveDog(fido); felix.name = catName; [ex.A]felix.friend = fido; [ex.B]felix.friend = animalDao.getDogByName(dogName); animalDao.saveCat(felix); } AnimalDao.java (extends HibernateDaoSupport) public Dog saveDog(Dog dog) { getHibernateTemplate().saveOrUpdate(dog); return dog } public Cat saveCat(Cat cat) { getHibernateTemplate().saveOrUpdate(cat); return cat; } public Dog getDogByName(String name) { return (Dog) getHibernateTemplate().find("from Dog where name=?", name).get(0); } Now, assume for a minute that I would like to use either example A or example B to save my friend. Is one better than the other to use? I'll understand if neither of those examples work, but please explain why.

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• How to best launch C++ application from web page

  - by JB

  I guess there are two parts to this question, one technical and one best practice for security and doing things "right". I'm working on a little game using C++ / directx but I would like to be able to launch it from a web page by someone clicking on a link on that page. Ideally I would like the first time they clicked for it to launch an installer downloads and installs the game on their machine, and then the next time to launch an application which updates the game from a web site if it's old and then launches it. I have no problems with the expected security popups and questions the first time it runs. I want people to be certain what they are installing and understand what they are doing. But it would be nice if once it is installed they could run it with the minimum of fuss. My question then is what technologies I could use to do this? I'm thinking that it would need a browser plugin and an activex control so that first time you'd install that, and subsequently the control/plugin would be able to launch the game. I'm not sure that under newer browser secuity models that a plugin would have the permissions to be able to run an installer though or silently invoke applications on the client machine even if they are already installed. Is there a more sensible way to achive what I want to achieve? And I'm worried about the security aspects too. I want this to be convenient for users but I of course want to do it "right". I know this can be done as I've seen several mmorpg type games that launch in this way from the browser now but it's not entirely clear to me how they've done it.

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• What is the best way using multiple lines of <% %> Tag or <% %> Tag with multiple lines?

  - by Salil

  Sorry if the title is not enough to understand what i am asking about. I am rails developer and i used multiple lines of <% % in my views but now i realized that it's not best practice so i came here and like to you all excellent guys what is the correct way in ROR? For example if i required to something like following <% user =User.all %> <% name= [] %> <% count = 0 %> <% for user in users %> <% name << user.name %> <% count+=1%> <% end %> Can i do it as follows ? <% user =User.all name= [] count = 0 for user in users name << user.name count+=1 end %> I know better way of collecting element from array But above is just example. But my question is, is it possible and if yes which is the correct way?

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• Program structure in long running data processing python script

  - by fmark

  For my current job I am writing some long-running (think hours to days) scripts that do CPU intensive data-processing. The program flow is very simple - it proceeds into the main loop, completes the main loop, saves output and terminates: The basic structure of my programs tends to be like so: <import statements> <constant declarations> <misc function declarations> def main(): for blah in blahs(): <lots of local variables> <lots of tightly coupled computation> for something in somethings(): <lots more local variables> <lots more computation> <etc., etc.> <save results> if __name__ == "__main__": main() This gets unmanageable quickly, so I want to refactor it into something more manageable. I want to make this more maintainable, without sacrificing execution speed. Each chuck of code relies on a large number of variables however, so refactoring parts of the computation out to functions would make parameters list grow out of hand very quickly. Should I put this sort of code into a python class, and change the local variables into class variables? It doesn't make a great deal of sense tp me conceptually to turn the program into a class, as the class would never be reused, and only one instance would ever be created per instance. What is the best practice structure for this kind of program? I am using python but the question is relatively language-agnostic, assuming a modern object-oriented language features.

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• Object Oriented Programming Problem

  - by Danny Love

  I'm designing a little CMS using PHP whilst putting OOP into practice. I've hit a problem though. I have a page class, whos constructor accepts a UID and a slug. This is then used to set the properties (unless the page don't exist in which case it would fail). Anyway, I wanted to implement a function to create a page, and I thought ... what's the best way to do this without overloading the constructor. What would the correct way, or more conventional method, of doing this be? My code is below: <?php class Page { private $dbc; private $title; private $description; private $image; private $tags; private $owner; private $timestamp; private $views; public function __construct($uid, $slug) { } public function getTitle() { return $this->title; } public function getDescription() { if($this->description != NULL) { return $this->description; } else { return false; } } public function getImage() { if($this->image != NULL) { return $this->image; } else { return false; } } public function getTags() { if($this->tags != NULL) { return $this->tags; } else { return false; } } public function getOwner() { return $this->owner; } public function getTimestamp() { return $this->timestamp; } public function getViews() { return $this->views; } public function createPage() { // Stuck? } }

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• Including partial views when applying the Mode-View-ViewModel design pattern

  - by Filip Ekberg

  Consider that I have an application that just handles Messages and Users I want my Window to have a common Menu and an area where the current View is displayed. I can only work with either Messages or Users so I cannot work simultaniously with both Views. Therefore I have the following Controls MessageView.xaml UserView.xaml Just to make it a bit easier, both the Message Model and the User Model looks like this: Name Description Now, I have the following three ViewModels: MainWindowViewModel UsersViewModel MessagesViewModel The UsersViewModel and the MessagesViewModel both just fetch an ObserverableCollection<T> of its regarding Model which is bound in the corresponding View like this: <DataGrid ItemSource="{Binding ModelCollection}" /> The MainWindowViewModel hooks up two different Commands that have implemented ICommand that looks something like the following: public class ShowMessagesCommand : ICommand { private ViewModelBase ViewModel { get; set; } public ShowMessagesCommand (ViewModelBase viewModel) { ViewModel = viewModel; } public void Execute(object parameter) { var viewModel = new ProductsViewModel(); ViewModel.PartialViewModel = new MessageView { DataContext = viewModel }; } public bool CanExecute(object parameter) { return true; } public event EventHandler CanExecuteChanged; } And there is another one a like it that will show Users. Now this introduced ViewModelBase which only holds the following: public UIElement PartialViewModel { get { return (UIElement)GetValue(PartialViewModelProperty); } set { SetValue(PartialViewModelProperty, value); } } public static readonly DependencyProperty PartialViewModelProperty = DependencyProperty.Register("PartialViewModel", typeof(UIElement), typeof(ViewModelBase), new UIPropertyMetadata(null)); This dependency property is used in the MainWindow.xaml to display the User Control dynamicly like this: <UserControl Content="{Binding PartialViewModel}" /> There are also two buttons on this Window that fires the Commands: ShowMessagesCommand ShowUsersCommand And when these are fired, the UserControl changes because PartialViewModel is a dependency property. I want to know if this is bad practice? Should I not inject the User Control like this? Is there another "better" alternative that corresponds better with the design pattern? Or is this a nice way of including partial views?

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• Entity Framework autoincrement key

  - by Tommy Ong

  I'm facing an issue of duplicated incremental field on a concurrency scenario. I'm using EF as the ORM tool, attempting to insert an entity with a field that acts as a incremental INT field. Basically this field is called "SequenceNumber", where each new record before insert, will read the database using MAX to get the last SequenceNumber, append +1 to it, and saves the changes. Between the getting of last SequenceNumber and Saving, that's where the concurrency is happening. I'm not using ID for SequenceNumber as it is not a unique constraint, and may reset on certain conditions such as monthly, yearly, etc. InvoiceNumber | SequenceNumber | DateCreated INV00001_08_14 | 1 | 25/08/2014 INV00001_08_14 | 1 | 25/08/2014 <= (concurrency is creating two SeqNo 1) INV00002_08_14 | 2 | 25/08/2014 INV00003_08_14 | 3 | 26/08/2014 INV00004_08_14 | 4 | 27/08/2014 INV00005_08_14 | 5 | 29/08/2014 INV00001_09_14 | 1 | 01/09/2014 <= (sequence number reset) Invoice number is formatted based on the SequenceNumber. After some research I've ended up with these possible solutions, but wanna know the best practice 1) Optimistic Concurrency, locking the table from any reads until the current transaction is completed (not fancy of this idea as I guess performance will be of a great impact?) 2) Create a Stored Procedure solely for this purpose, does select and insert on a single statement as such concurrency is at minimum (would prefer a EF based approach if possible)

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• How do I keep my DataService up to date with ObservableCollection?

  - by joebeazelman

  I have a class called CustomerService which simply reads a collection of customers from a file or creates one and passes it back to the Main Model View where it is turned into an ObservableCollection. What the best practice for making sure the items in the CustomerService and ObservableCollection are in sync. I'm guessing I could hookup the CustomerService object to respond to RaisePropertyChanged, but isn't this only for use with WPF controls? Is there a better way? using System; public class MainModelView { public MainModelView() { _customers = new ObservableCollection<CustomerViewModel>(new CustomerService().GetCustomers()); } public const string CustomersPropertyName = "Customers" private ObservableCollection<CustomerViewModel> _customers; public ObservableCollection<CustomerViewModel> Customers { get { return _customers; } set { if (_customers == value) { return; } var oldValue = _customers; _customers = value; // Update bindings and broadcast change using GalaSoft.MvvmLight.Messenging RaisePropertyChanged(CustomersPropertyName, oldValue, value, true); } } } public class CustomerService { /// <summary> /// Load all persons from file on disk. /// </summary> _customers = new List<CustomerViewModel> { new CustomerViewModel(new Customer("Bob", "" )), new CustomerViewModel(new Customer("Bob 2", "" )), new CustomerViewModel(new Customer("Bob 3", "" )), }; public IEnumerable<LinkViewModel> GetCustomers() { return _customers; } }

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• Is unnecessary error handling recommended in business logic? eg. Null check/Percentage limit check etc

  - by novice_at_work

  We usually put unnecessary checks in our business logic to avoid failures. Eg. 1. public ObjectABC funcABC(){ ObjectABC obj = new ObjectABC; .......... .......... //its never set to null here. .......... return obj; } ObjectABC o = funABC(); if(o!=null){ //do something } Why do we need this null check if we are sure that it will never be null? Is it a good practice or not? 2. int pplReached = funA(..,..,..); int totalPpl = funB(..,..,..); funA() just puts a few more restriction over result of funB(). Double percentage = (totalPpl==0||totalPpl<pplReached) ? 0.0 : pplReached/totalPpl; Do we again need this check? The questions is: Aren't we swallowing some fundamental issue by putting such checks? Issues which should be shown ideally, are avoided by putting these checks. What is the recommended way?

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• ASP Dot Net : How to repeat HTML parts with minor differences on a page?

  - by tinky05

  It's a really simple problem. I've got HTML code like this : <div> <img src="image1.jpg" alt="test1" /> </div> <div> <img src="image2.jpg" alt="test2" /> </div> <div> <img src="image3.jpg" alt="test3" /> </div> etc... The data is comming from a DB (image name, alt text). In JAVA, I would do something like : save the info in array in the back end. For the presentation I would loop through it with JSTL : <c:foeach items="${data}" var="${item}> <div> <img src="${item.image}" alt="${item.alt}" /> </div> </c:foreach> What's the best practice in ASP.net I just don't want to create a string with HTML code in it in the "code behind", it's ugly IMO.

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• How do I switch out Views in a Cocoa application?

  - by David Garcia

  So I'm beginning to learn how to use Cocoa. I think I've pretty much got it but I'm hung up on creating and switching views. I'm rewriting a game I made a little bit ago for practice. All I want is one window (preferably not resizable) and I want to be able to switch out views for different screens in the game. First, I have the main menu (Start Game, High Scores, Exit). Then I need a window for each screen (Gameplay screen, Highscore screen). What I'm getting confused with is how to design this. I looked up NSViewController thinking it manages views but it doesn't. It only manages one view by loading it really. I don't understand why I'd need to use NSViewController then. Couldn't I just have a window class that contains multiple subclasses of NSView and load them like that? I'm not sure I understand the purpose of the ViewController. Does my Window Class really need to subclass NSWindowController? I was trying to follow the example of Apple's ViewController example and it has a window controller class that's a subclass of NSWindowController. I don't see what the purpose was of subclassing that. All NSWindowController seems to add is - initWithPath:(NSString *)newPath but I fail to see the use in that either when I can just edit the plist file to open the window on start up. Apple's example also has an NSView variable and an NSViewController variable. Don't you only need one variable to store the current view? Thanks in advance guys, I'm really confused as to how this works.

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• JavaScript window object element properties

  - by Timothy

  A coworker showed me the following code and asked me why it worked. <span id="myspan">Do you like my hat?</span> <script type="text/javascript"> var spanElement = document.getElementById("myspan"); alert("Here I am! " + spanElement.innerHTML + "\n" + myspan.innerHTML); </script> I explained that a property is attached to the window object with the name of the element's id when the browser parses the document which then contains a reference to the appropriate dom node. It's sort of as if window.myspan = document.getElementById("myspan") is called behind the scenes as the page is being rendered. The ensuing discussion we had raised a few of questions: The window object and most of the DOM are not part of the official JavaScript/ECMA standards, but is the above behavior documented in any other official literature, perhaps browser-related? The above works in a browser (at least the main contenders) because there is a window object, but fails in something like rhino. Is writing code that relys on this considered bad practice because it makes too many assumptions about the execution environment? Are there any browsers in which the above would fail, or is this considered standard behavior across the board? Does anyone here know the answers to those questions and would be willing to enlighten me? I tried a quick internet search, but I admit I'm not sure how to even properly phrase the query. Pointers to references and documentation are welcome.

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