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  • Do I still have to implement a singleton class by hand in .net, even when using .Net4.0?

    - by Hamish Grubijan
    Once the singleton pattern is understood, writing subsequent singleton classes in C# is a brainless exercise. I would hope that the framework would help you by providing an interface or a base class to do that. Here is how I envision it: public sealed class Schablone : ISingleton<Schablone> { // Stuff forced by the interface goes here // Extra logic goes here } Does what I am looking for exist? Is there some syntactic sugar for constructing a singleton class - whether with an interface, a class attribute, etc.? Can one write a useful and bullet-proof ISingleton themselves? Care to try? Thanks!

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  • javascript singleton question

    - by Shawn
    I just read a few threads on the discussion of singleton design in javascript. I'm 100% new to the Design Pattern stuff but as I see since a Singleton by definition won't have the need to be instantiated, conceptually if it's not to be instantiated, in my opinion it doesn't have to be treated like conventional objects which are created from a blueprint(classes). So my wonder is why not just think of a singleton just as something statically available that is wrapped in some sort of scope and that should be all. From the threads I saw, most of them make a singleton though traditional javascript new function(){} followed by making a pseudo constructor. Well I just think an object literal is enough enough: var singleton = { dothis: function(){}, dothat: function(){} } right? Or anybody got better insights? [update] : Again my point is why don't people just use a simpler way to make singletons in javascript as I showed in the second snippet, if there's an absolute reason please tell me. I'm usually afraid of this kind of situation that I simplify things to much :D

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  • In the JSON spec, what does "Since the first two characters of a JSON text will always be ASCII characters" mean?

    - by dan gibson
    The spec is http://www.ietf.org/rfc/rfc4627.txt?number=4627 It contains this: Encoding JSON text SHALL be encoded in Unicode. The default encoding is UTF-8. Since the first two characters of a JSON text will always be ASCII characters [RFC0020], it is possible to determine whether an octet stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking at the pattern of nulls in the first four octets. What does it mean "Since the first two characters of a JSON text will always be ASCII characters [RFC0020]"? I've looked at RFC0020 but couldn't find anything about it. JSON could be {" or { " (ie whitespace before the quote.

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  • Unit Testing User Interface. What is an effective way ?

    - by pierocampanelli
    I have an accounting & payroll client/server application where there are several input form with complex data validation rules. I am finding an effective way to perform unit testing of user interface. For complex validation rules I mean: "Disable button X if I Insert a value in textfield Y" "Enable a combobox if I insert a value in a textfield" ...... ...... Most promising pattern i have found is suggested by M. Fowler (http://martinfowler.com/eaaDev/ModelViewPresenter.html). Have you any experience about Unit Testing of User Interface? As technology stack I am using: .NET 3.5 & Windows Forms Widget Library.

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  • regular expression and escaping

    - by pstanton
    Sorry if this has been asked, my search brought up many off topic posts. I'm trying to convert wildcards from a user defined search string (wildcard is "*") to postgresql like wildcard "%". I'd like to handle escaping so that "%" => "\%" and "\*" => "*" I know i could replace \* with something else prior to replacing * and then swap it back, but i'd prefer not to and instead only convert * using a pattern that selects it when not proceeded by \. String convertWildcard(String like) { like = like.replaceAll("%", "\\%"); like = like.replaceAll("\\*", "%"); return like; } Assert.assertEquals("%", convertWildcard("*")); Assert.assertEquals("\%", convertWildcard("%")); Assert.assertEquals("*", convertWildcard("\*")); // FAIL Assert.assertEquals("a%b", convertWildcard("a*b")); Assert.assertEquals("a\%b", convertWildcard("a%b")); Assert.assertEquals("a*b", convertWildcard("a\*b")); // FAIL ideas welcome.

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  • How useful are design patterns when it comes to web programming?

    - by Raja
    Background: My organization uses Microsoft .Net (3.5) with SQL Server 2005 as back end. With RAD being the norm and Agile being the widely used process. I have always found using design patterns difficult since it involves a bit more understanding and bit more training. Can you give me some examples where design patterns have solved real time problems in Web programming? What is the criteria for using any design pattern? What is the benefit reaped from it. I know it is a general question but this would help me a bunch.

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  • Using NSThread to solve waiting for image from URL on the iPhone

    - by james.ingham
    So I have the following code in a method which I want to set a UIImageView image to that of one from an online source: [NSThread detachNewThreadSelector:@selector(loadImage) toTarget:self withObject:nil]; Then in the method called by the thread I have this: - (void) loadImage { NSURL *url = [NSURL URLWithString:logoPath]; // logoPath is an NSString with path details NSData *data = [NSData dataWithContentsOfURL:url]; logoImage.image = [UIImage imageWithData:data]; } This works great however I get many warnings within the Debugger Console along the lines of: 2010-05-10 14:30:14.052 ProjectTitle[2930:633f] * _NSAutoreleaseNoPool(): Object 0x169d30 of class NSHTTPURLResponse autoreleased with no pool in place - just leaking This occurs many times each time I call the new thread and then eventually, under no pattern, after calling a few of these threads I get the classic 'EXC_BAD_ACCESS' run-time error. I understand that this is happening because I'm not retaining the object but how can I solve this with the code in 'loadImage' shown above? Thanks

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  • String Functions in IIS Url Rewritting Module

    - by Nariman
    The IIS URL Rewrite Module ships with 3 built-in functions: * ToLower - returns the input string converted to lower case. * UrlEncode - returns the input string converted to URL-encoded format. This function can be used if the substitution URL in rewrite rule contains special characters (for example non-ASCII or URI-unsafe characters). * UrlDecode - decodes the URL-encoded input string. This function can be used to decode a condition input before matching it against a pattern. The functions can be invoked by using the following syntax: {function_name:any_string} The question is: can this list be extended by introducing a Replace function that's available for changing values within a rewrite rule action or condition?

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  • Proper design a Model-Controller in Cocoa?

    - by legege
    Hi, I'm trying to design a simple Cocoa application and I would like to have a clear and easy to understand software architecture. Of course, I'm using a basic MVC design and my question concerns the Model layer. For my application, the Model represents data fetched on the Internet with a XML-RPC API. I'm planning to use Core Data to represent a locally fetched version. How should the data be loaded initially? I'm reading the Cocoa Design Pattern book, and they talk about a Model-Controller that is centric to the Model. How would that be done? Thanks!

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  • Singelton on iPhone Simulator vs Singelton on real Device

    - by Helge Becker
    I am using a Singelton for some shared stuff. In the simulator, the app crashes ocasionally. Tracking the crash down shows that the the properties of my Singelton became dealocated. Those crashes never happend on a real device. Does the iPHone simulator handle memory managemend different? GC maybe? Changed the singelton to match this pattern. The iPhone Simulator dont crash now, but I am not sure about the memory handling on the real device. I assume that this solution will cause problems. What do you think?

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  • Routing Error in Chapter 7.1.2 of the Ruby on Rails Tutorial

    - by user2985910
    I've been working through the tutorial for the past few days, and finally hit a snag in chapter 7. It is in this step where the line in routes.rb: get "users/new" is replaced with resource :users After I do this, I get a routing error when visiting http://localhost:3000/users/1 - No route matches [GET] "/users/1" instead of the other "Unknown Action" error shown here. Per the instructions, my routes.db file looks like this: SampleApp::Application.routes.draw do resource :users root "static_pages#home" match '/signup', to: 'users#new', via: 'get' match '/help', to: 'static_pages#help', via: 'get' match '/about', to: 'static_pages#about', via: 'get' match '/contact', to: 'static_pages#contact', via: 'get' end Output from 'rake routes' shows: Prefix Verb URI Pattern Controller#Action users POST /users(.:format) users#create new_users GET /users/new(.:format) users#new edit_users GET /users/edit(.:format) users#edit GET /users(.:format) users#show PATCH /users(.:format) users#update PUT /users(.:format) users#update DELETE /users(.:format) users#destroy root GET / static_pages#home signup GET /signup(.:format) users#new help GET /help(.:format) static_pages#help about GET /about(.:format) static_pages#about contact GET /contact(.:format) static_pages#contact Does anyone have any insight to get past this? Many thanks.

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  • Why use hashing to create pathnames for large collections of files?

    - by Stephen
    Hi, I noticed a number of cases where an application or database stored collections of files/blobs using a has to determine the path and filename. I believe the intended outcome is a situation where the path never gets too deep, or the folders ever get too full - too many files (or folders) in a folder making for slower access. EDIT: Examples are often Digital libraries or repositories, though the simplest example I can think of (that can be installed in about 30s) is the Zotero document/citation database. Why do this? EDIT: thanks Mat for the answer - does this technique of using a hash to create a file path have a name? Is it a pattern? I'd like to read more, but have failed to find anything in the ACM Digital Library

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  • Key Value Observation (ala Cocoa) in GWT ?

    - by user179997
    Hi all, There are these 2 frameworks out there in the same "cloud application" space as GWT: Sproutcore and Cappuccino. Cappuccino is Cocoa for the web, Sproutcore is Cocoa-like and one very central idea in both is Key Value Observation where the framework itself provides the glue to change all dependencies of an object when it changes, and you only have to declare those dependencies. If that was too poorly expressed please see this presentation: http://www.infoq.com/presentations/subelsky-sproutcore-intro Since the pattern reduces the amount of code you type it reduces the number of bugs. Maybe it's too much to ask but I would like to have that and all the benefits of Eclipse/compiler that come with GWT. Is there support for this in GWT, or a library already developed? Or maybe there is support in some of the component libraries for GWT out there? Thanks

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  • sed replacement does not work

    - by Robin Hood
    Hello, I have trouble using sed. I need to replace some lines in very deprecated HTML sites which consist of many files. My script does not work and I do not why. When I tried to find exact pattern with Netbeas it worked. find . -type f -name "*.htm?" -exec sed -i -r 's/ing\. Šuhajda Dušan\, Mírová 767\, 518 01 Dobruška\, \+420 737 980 333\,/REPLACEMENT/g' {} \; Where is the mistake? Is there an alternative to replace text without searching regular expression but plain text? Thanks for any respond.

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  • Process a batch of items, return an object to report on status

    - by Naeem Sarfraz
    I'm looking for a pattern (or good practice) for the following scenario: My function List<BatchItemResponse> Process(List<BatchItem> Data) {..} will process a list of data, and return info on where each item in the batch could be processed. struct BatchItemResponse { int BatchItemID; bool Processed; string Description; } Any thoughts? Is what I've proposed as good as it gets?

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  • How to deal with the new line character in the Silverlight TextBox

    - by Ian Oakes
    When using a multi-line TextBox (AcceptsReturn="True") in Silverlight, line feeds are recorded as \r rather than \r\n. This is causing problems when the data is persisted and later exported to another format to be read by a Windows application. I was thinking of using a regular expression to replace any single \r characters with a \r\n, but I suck at regex's and couldn't get it to work. Because there may be a mixture of line endings just blindy replacing all \r with \r\n doesn't cut it. So two questions really... If regex is the way to go what's the correct pattern? Is there a way to get Silverlight to respect it's own Environment.NewLine character in TextBox's and have it insert \r\n rather just a single \r?

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  • design patterns for hierarchical structures

    - by JLBarros
    Anyone knows some design patterns for hierarchical structures? For example, to manage inventory categories, accounting chart of accounts, divisions of human resources, etc.. Thank you very much in advance EDIT: Thanks for your interest. I am looking for a better way of dealing with hierarchical items to which they should apply operations depending on the level of hierarchy. I have been studying the patterns by Martin Fowler, for example Accounting, but I wonder if there are other more generic. The problem is that operations apply to the items must be possible to change even at run time and may depend on other external variables. I thought of a kind of strategy pattern but would like to combine it with the fact that it is a hierarchical scheme. I would appreciate any reference to hierarchical patterns and you'll take care of them in depth.

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  • What patterns exist for web application development?

    - by DaveDev
    I understand that MVC & MVP are design patterns that are commonly used for web development, as well as ASP.NET WebForms (more of an anti-pattern, really!). What other patterns are used in web application development? I'm not necessarily saying I want to learn/use new patterns just to be different - I do believe there's a lot of value in taking the conventional route - but I think it's good to know what else is out there to be able to properly understand what I'm currently working with. Thanks.

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  • How to specify unique container styles for heterogenous hierarchies using SL3 and TreeView control

    - by rcecil
    Hello, Just look for strategies that have been successful in rendering hierarchies that represent inheritance structures using SL3/4 TreeViews. I need to render certain nodes differently than others, depending upon what kind of container they are (a choice between things, or simply a list of related things, etc.) So far, I've been very successful with the DataTemplate route: I've been able to use a technique described in Ted Glaza's post "Easy DataTemplateSelectors in Silverlight" (you may have retrieve a Google cache of this page). SO what I'm trying to discover is something on the order of a StyleSelector, not a DataTemplateSelector. I'm considering leveraging my current implementations of Glaza's pattern of selector objects to somehow detect the node type and set the ItemContainerStyle there, but it doesn't seem clear right now. Thanks for your thoughts.

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  • C#: Creating an editable object inside a PictureBox

    - by ET
    My goal is to let the user click on a specific location on a map to add a Placemark, and then edit the placemark by click its icon (change its name, move it around, etc). I am using a PictureBox to show the map, and by registering the MouseDoubleClick event I am drawing an Image on the map with GDI+ DrawImage() method. The problem is that after the placemark's Image was drawn, it does not editable: the user cant click the icon and move it around, change its name etc. Is there any other design pattern I can follow? maybe using other controls... ?

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  • How could I implement a fuzzy time date replacer using Knockout?

    - by rball
    I'd like to implement what this plugin does using jQuery: https://github.com/rmm5t/jquery-timeago A short description of that plugin: This will turn all abbr elements with a class of timeago and an ISO 8601 timestamp in the title (conforming to the datetime design pattern microformat): <abbr class="timeago" title="2011-12-17T09:24:17Z">December 17, 2011</abbr> Into something like this: <abbr class="timeago" title="December 17, 2011">about 1 day ago</abbr> Except using knockout my markup looks like this: <abbr data-bind="attr: { title: Posted }" class="timeago"></abbr> I think something isn't synced up because nothing is happening even if I put the call to timeago within the viewmodel itself. I'm guessing I need a subscriber that's attached to the observable "Posted" but I'm not sure how to set that up.

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  • Why is 'using' improving C# performances

    - by Wernight
    It seems that in most cases the C# compiler could call Dispose() automatically. Like most cases of the using pattern look like: public void SomeMethod() { ... using (var foo = new Foo()) { ... } // Foo isn't use after here (obviously). ... } Since foo isn't used (that's a very simple detection) and since its not provided as argument to another method (that's a supposition that applies to many use cases and can be extended), the compiler could automatically call Dispose() without the developper requiring to do it. This means that in most cases the using is pretty useless if the compiler does some smart job. IDisposable seem low level enough to me to be taken in account by a compiler. Now why isn't this done? Wouldn't that improve the performances (if the developpers are... dirty).

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  • Help me understand Dispose() implementation code from MSDN

    - by Benny
    the following code is from MSDN: Idisposable pattern protected virtual void Dispose(bool disposing) { // If you need thread safety, use a lock around these // operations, as well as in your methods that use the resource. if (!_disposed) { if (disposing) { if (_resource != null) _resource.Dispose(); Console.WriteLine("Object disposed."); } // Indicate that the instance has been disposed. _resource = null; _disposed = true; } } why the following statement: _resource = null; _disposed = true; are not enclosed by if (disposing) statement block? for me i would probably write like this: if (disposing) { if (_resource != null) { _resource.Dispose(); _resource = null; _disposed = true; } Console.WriteLine("Object disposed."); } anything wrong with my version?

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  • Recommendations with hierarchical data on non-relational databases?

    - by Luki
    I'm developing an web application that uses a non-relational database as a backend (django-nonrel + AppEngine). I need to store some hierarchical data (projects/subproject_1/subproject_N/tasks), and I'm wondering which pattern should I use. For now I thought of: Adjacency List (store the item's parent id) Nested sets (store left and right values for the item) In my case, the depth of nesting for a normal user will not exceed 4-5 levels. Also, on the UI, I would like to have a pagination for the items on the first level, to avoid to load too many items at the first page load. From what I understand so far, nested sets are great when the hierarchy is used more for displaying. Adjacency lists are great when editing on the tree is done often. In my case I guess I need the displaying more than the editing (when using nested sets, even if the display would work great, the above pagination could complicate things on editing). Do you have any thoughts and advice, based on your experience with the non-relational databases?

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  • 'is instanceof' Interface bad design

    - by peterRit
    Say I have a class A class A { Z source; } Now, the context tells me that 'Z' can be an instance of different classes (say, B and C) which doesn't share any common class in their inheritance tree. I guess the naive approach is to make 'Z' an Interface class, and make classes B and C implement it. But something still doesn't convince me because every time an instance of class A is used, I need to know the type of 'source'. So all finishes in multiple 'ifs' making 'is instanceof' which doesn't sound quite nice. Maybe in the future some other class implements Z, and having hardcoded 'ifs' of this type definitely could break something. The escence of the problem is that I cannot resolve the issue by adding functions to Z, because the work done in each instance type of Z is different. I hope someone can give me and advice, maybe about some useful design pattern. Thanks

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