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  • C# Using singleton instead of a global static instance

    - by Farstucker
    I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me. Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc). There seems to be about 100 ways of creating a singleton but with some help from yoda I found some thread safe examples. ..so given the following code: public sealed class Singleton { public static Singleton Instance { get; private set; } static Singleton() { Instance = new Singleton(); } } How/Where would you instantiate the this new class and how should it be called from a separate class? Thanks for your help.

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  • creative way for implementing Data object with its corresponding business logic class in java

    - by ekeren
    I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity's sake let's call the classes Business a BusinessData and I prefix for their Interfaces. All the getter and setter are delegated from Business class to BusinessData class. I thought about implementing IBusinessData interface that will contain all the getter and setters and IBusiness interface that will extend it. I can either make Business extend BuisnessData so I will not need to implement all getter and setter delegates, or make some abstract class ForwardingBusinessData that will only delegate getter and setters. Any of the above option I lose my hierarchy freedom, do any of you have any creative solutions for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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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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  • Zend Framework Custom Validation Class Error Message

    - by remlabm
    The validation fails as it should but does not return the error message. $form->addElement('text', 'phone_number', array( 'required' => true, 'validators' => array( array('NotEmpty', true, array('messages' => 'Enter a valid Phone Number')), array('regex', false, array('pattern' => '/\([0-9]{3}\)\s[0-9]{3}-[0-9]{4}/', 'messages' => 'Enter a valid Phone Number' )), 'CheckPhoneNumber'), ), )); Custom Class: class Custom_Validators_CheckPhoneNumber extends Zend_Validate_Abstract{ const IN_USE = 'inUse'; protected $_messageTemplates = array( self::IN_USE => "'%value%' is currently in use" ); public function isValid($value) { $this->_setValue($value); $user_check = Users::getActive(preg_replace("/[^0-9]/", "", $value)); if($user_check->id){ $this->_error(self::IN_USE); return false; } return true; } } Just fails does not give the "IN_USE" error.

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  • Entity Framework 4: C# !(ReferenceEquals()) vs !=

    - by Eric J.
    Unless a class specifically overrides the behavior defined for Object, ReferenceEquals and == do the same thing... compare references. In property setters, I have commonly used the pattern private MyType myProperty; public MyType MyProperty { set { if (myProperty != value) { myProperty = value; // Do stuff like NotifyPropertyChanged } } } However, in code generated by Entity Framework, the if statement is replaced by if (!ReferenceEquals(myProperty, value)) Using ReferenceEquals is more explicit (as I guess not all C# programmers know that == does the same thing if not overridden). Is there any difference that's escaping me between the two if-variants? Are they perhaps accounting for the possibility that POCO designers may have overridden ==? In short, if I have not overridden ==, am I save using != instead of ReferencEquals()?

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  • Efficient persistent storage for simple id to table of values map for java

    - by wds
    I need to store some data that follows the simple pattern of mapping an "id" to a full table (with multiple rows) of several columns (i.e. some integer values [u, v, w]). The size of one of these tables would be a couple of KB. Basically what I need is to store a persistent cache of some intermediary results. This could quite easily be implemented as simple sql, but there's a couple of problems, namely I need to compress the size of this structure on disk as much as possible. (because of amount of values I'm storing) Also, it's not transactional, I just need to write once and simply read the contents of the entire table, so a relational DB isn't actually a very good fit. I was wondering if anyone had any good suggestions? For some reason I can't seem to come up with something decent atm. Especially something with an API in java would be nice.

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  • Styling a list as tabs with a background overflowing into content

    - by Litso
    I couldn't think of any better way to name this question, but I'll explain. I have a mediawiki website with a background pattern (like parchment) behind the articles. At the top of each article I want to have tabs like wikipedia does (with page | talk | edit etc links). The problem is, the tabs should seamlessly fit with the article's background and I can't figure out if this is actually possible. The way I was trying to do it was positioning the list inside the actual content div and give the <li items a transparent background, but as far as I can see there's no way to color the rest of the <ul's background black without affecting the <li's in there. Anyone have an idea? (example url: http://dev.mansonwiki.com/wiki/Sandbox )

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  • Thread used for ServiceConnection callback (Android)

    - by Jannick
    Hi I'm developing an activity that binds to a local service (in onCreate of the activity): bindService(new Intent(this, CommandService.class), svcConn, BIND_AUTO_CREATE); I would like to be able to call methods through the IBinder in my lifecycle methods, but can not be sure that onServiceConnected have been called prior to these. I'm thinking of handling this by adding a queue of sorts in the ServiceConnection implementation, so that the method calls (Command pattern) will be executed once the connection is established. My questions are then: Is this stupid, any better ways? :) Are there any specification for which thread will be used to execute the ServiceConnection callbacks? More to the point, do I need to worry about synchronizing a queue datastructure? Edit - something like: public void onServiceConnected(ComponentName name, IBinder service) { dispatchService = (DispatchAsync)service; for(ExecutionTask task : queue){ dispatchService.execute(task.getCommand(), task); } }

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  • Why state cannot be part of Presenter in MVP?

    - by rFactor
    I read http://www.codeproject.com/KB/architecture/MVC_MVP_MVVM_design.aspx and it said: As powerful as they are, both MVC and MVP have their problems. One of them is persistence of the View’s state. For instance, if the Model, being a domain object, does not know anything about the UI, and the View does not implement any business logic, then where would we store the state of the View’s elements such as selected items? Fowler comes up with a solution in the form of a Presentation Model pattern. I wonder why Presenter can't hold View state? It already holds all View logic. As far as I understand, in MVC and MVP the state is kept in View. In PM and MVVM the state is kept in the Presentation Model. Why can't Presenter follow PM in this particular case and contain the state of the view? Here is another article which says Presenter does not hold View state, instead the view does: http://www.codeproject.com/KB/aspnet/ArchitectureComparison.aspx

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  • Convert inline image tags like [image:123:title:size] into HTML img tags

    - by Jacques Joubert
    I am looking for help with regular expression $pattern to convert inline image tags like [image:123:title:size] into HTML img tags. here is the code: //[image:ID:caption:size] $content = '[image:38:title:800x900]'; preg_match_all( '/\[image:(\d+)(:?)([^\]]*)\]/i', $content, $images ); if( !empty( $images[0] ) ) { // There are image inline tags in the content foreach( $images[0] as $i => $tag ) { $link_ID = (int)$images[1][$i]; $caption = empty( $images[2][$i] ) ? '#' : $images[3][$i]; $size = empty( $images[4][$i] ) ? '#' : $images[4][$i]; } echo '<br />'; echo 'ID: '.$link_ID.'<br />'; echo 'Tag: '.$caption.'<br />'; echo 'size: '.$size.'<br />'; } which outputs: ID: 12 Tag: caption:size size: # Any help would be great!

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  • jQuery/javascript events - prototype event handler

    - by Brian M. Hunt
    The following code doesn't work as I intuitively expect it to: function MyObject(input) { input.change(this._foo); this.X = undefined; } MyObject.prototype._foo = function() { alert("This code is never called"); // but if it did this.X = true; } var test_input = $("input#xyz"); // a random, existing input var m = MyObject(test_input); // attach handler (or try to) test_input.change(); // trigger event alert(m.X); // undefined I'd expect that _foo() would be called (and, if that ever happens, that the this variable in _foo() would be an instantiation of MyObject. Does anyone know why this doesn't work, and of any alternative pattern for passing an object to an event handler? Thank you for reading. Brian

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  • database vs flat file, which is a faster structure for regex matching with many simultaneous request

    - by Jamex
    Hi, which structure returns faster result and/or less taxing on the host server, flat file or database (mysql)? Assume many users (100 users) are simultaneously query the file/db. Searches involve pattern matching using regex against a static file/db. File has 50,000 unique lines (same data type). There could be many matches. There is no writing to the file/db, just read. Is it possible to have a duplicate the file/db and write a logic switch to use the backup file/db if the main file is in use? Which language is best for the type of structure? Perl for flat and PHP for db? TIA

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  • Different background colors for the top and bottom of a UITableView

    - by Aaron Brethorst
    If you look at your Inbox in iPhone OS 3.0's Mail app, you'll see that swiping down displays a grayish background color above the UISearchBar. Now, if you scroll down to the bottom of the table, you'll see that the background color at that end is white. I can think of a couple ways of solving this problem, but they're pretty hacky: Change the table view's background color depending on the current scrollOffset by overriding -scrollViewDidScroll: Give the UITableView a clear background color and then set its superview's backgroundColor to a gradient pattern image. Does anyone know what the "best practice" solution is for this problem? thanks.

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  • How would MVVM be for games?

    - by Benny Jobigan
    Particularly for 2d games, and particularly silverlight/wpf games. If you think about it, you can divide a game object into its view (the graphic on the screen) and a view-model/model (the state, ai, and other data for the object). In silverlight, it seems common to make each object a user control, putting the model and view into a single object. I suppose the advantage of this is simplicity. But, perhaps it's less clean or has some disadvantages in terms of the underlying "game engine". What are your thoughts on this matter? What are some advantages and disadvantages of using the MVVM pattern for game development? How about performance? All thoughts are welcome.

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  • Is it a bad idea to have a login dialog inside an iframe?

    - by AyKarsi
    We're creating a website where we will be giving out code snippets to our users which they can place on their own websites. These snippets contain a link a javascript include. When clicking the link, an iframe containing the login dialog to our site opens. The user then authenticates inside the iframe, does his work and when he leaves the iframe his session is closed. We've got it working allready and it's very slick. Our main concern though is phishing. The user has absolutely now way of veryifying where the login page is really coming from. On the other hand, phising attacks are also succesfull even if the user can see the fake-url in the address bar. Would you enter your (OpenId) credentials in an iframe? Does anyone know a pattern with which we could minimise the chances of a phishing attack?

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  • UNIX-style RegExp Replace running extremely slowly under windows. Help?

    - by John Sullivan
    I'm trying to run a unix regEXP on every log file in a 1.12 GB directory, then replace the matched pattern with ''. Test run on a 4 meg file is took about 10 minutes, but worked. Obviously something is murdering performance by several orders of magnitude. Find: ^(?!.*155[0-2][0-9]{4}\s.*).*$ -- NOTE: match any line NOT starting 152[0-2]NNNN where in is a number 0-9. Replace with: ''. Is there some justifiable reason for my regExp to take this long to replace matching text, or is the program I am using (this is windows / a program called "grepWin") most likely poorly optimized? Thanks.

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  • Restrict violation of architecture - asp.net MVP

    - by Srikanth
    If we had a defined hierarchy in an application. For ex a 3 - tier architecture, how do we restrict subsequent developers from violating the norms? For ex, in case of MVP (not asp.net MVC) architecture, the presenter should always bind the model and view. This helps in writing proper unit test programs. However, we had instances where people directly imported the model in view and called the functions violating the norms and hence the test cases couldn't be written properly. Is there a way we can restrict which classes are allowed to inherit from a set of classes? I am looking at various possibilities, including adopting a different design pattern, however a new approach should be worth the code change involved.

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  • htaccess Redirect - First Segment to PHP File, Second Segment as Parameter

    - by Steve
    My htaccess redirect knowledge is somewhat weak, so I was hoping to get some help here. I currently have the following redirect, which works well: # remove trailing slash RewriteRule ^(.*)/$ /$1 [L,R=301] # redirect to clean URL RewriteCond /%{REQUEST_FILENAME}.php -f RewriteRule ^([a-zA-Z0-9_-\s]+)$ /$1.php This takes a URL like www.mysite.com/about to www.mysite.com/about.php Now I would like to keep this behavior, but add parameters (if applicable), as such: www.mysite.com/about = www.mysite.com/about.php www.mysite.com/gallery/1 = www.mysite.com/gallery.php?id=1 If possible, I might like to expand this system to 2 or more parameters, as such: www.mysite.com/gallery/1/2 = www.mysite.com/gallery.php?id=1&section=2 So the pattern would be: First URL segment redirects to a PHP file (Optionally) the second segment gets added as the id parameter (Optionally) the third segment gets added as the section parameter

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  • Insert A Line At The Beginning Of A File

    - by thebourneid
    I'm trying to insert/add a line 'COMMENT DUMMY' at the beginnig of a file as a first row if /PATTERN/ not found. I know how to do this with OPEN CLOSE function. Probably after reading the file it should look something like this: open F, ">", $fn or die "could not open file: $!"; ; print F "COMMENT DUMMY\n", @array; close F; But I have a need to implement this with the use of the Tie::File function and don't know how. use strict; use warnings; use Tie::File; my $fn = 'test.txt'; tie my @lines, 'Tie::File', $fn or die "could not tie file: $!"; untie @lines;

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  • Best way to bind node collection to itemscontrol in Silverilght

    - by mrtrombone
    I have a Silverlight project where the main objects are just a bunch of nodes that are joined to each other. A parent node can have many children. I want to be able to bind the nodes to an itemscontrol or similar and so was wondering how to best structure the parent child relationship. Is it OK to create a flat top level list of all nodes (List allNodes) and add each node to that, binding the list to the itemscontrol, then on top of that add each node to it's parent's 'childnodes' list to establish the structure - or am I doing some kind of ugly doubling up? Just hoping there is some kind of best practice or pattern I can latch on to Thanks

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  • Creating/compling .net data class within an application

    - by MrTelly
    Is there a pattern, Xml structure, architecture technique we can use to create simple data holder class code that we can deserialise to/from and do that at runtime? We're in the early design stage of a .Net project and one of our goals is to make the resulting system extensible through configuration without needing a developer. We need to support new sources of data, typcially delivered as Xml messages. Currently we convert/deserialise the messages into simple classes and then use an already existing language which can manipulate those classes as we need. That works well when you have a developer to map the Xml to simple class, create the class and then write the deserialisation, but it's not extensible for for an administrator. Our target user audience is high end DBA and/or network admin - people who can handle Xml but may not know C#.

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  • Is it possible to listen to relational database update?

    - by Morgan Cheng
    Is it possible to listen to relation database update? For example, my web app want to send data update to client through Comet technology. I can have the program to poll the database periodically, but that would not be performant and scalable. If app can hood to a "event handler" of database, then app can get notification every time given database table data is updated. This sounds more promising, but I didn't find any concrete example for it. This is listener pattern. Does common relational database support such feature?

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  • Cocos2d: is it good practice to use a shared GameScene when having various levels?

    - by mm24
    In my code (based on the ShootEmUp example in this book, which I highly reccomend, source code in chapter 8 available here) I often use the trick of accessing the GameScene via: +(GameScene*) sharedGameScene; which returns a reference to the static instance of GameScene. Is a static instance of GameScene as in the book still a valid pattern in case I want a MainMenu calling GameScene initialized with different level data each time (e.g. different enemies)? (I have created a sceneWithId:(int) method where I load different level data each time. Or should I pheraps create a GameScene class and then sublcass it? E.g. FirstGameScene : GameScene

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  • How to set default values to all wrong or null parameters of method?

    - by Roman
    At the moment I have this code (and I don't like it): private RenderedImage private RenderedImage getChartImage (GanttChartModel model, String title, Integer width, Integer height, String xAxisLabel, String yAxisLabel, Boolean showLegend) { if (title == null) { title = ""; } if (xAxisLabel == null) { xAxisLabel = ""; } if (yAxisLabel == null) { yAxisLabel = ""; } if (showLegend == null) { showLegend = true; } if (width == null) { width = DEFAULT_WIDTH; } if (height == null) { height = DEFAULT_HEIGHT; } ... } How can I improve it? I have some thoughts about introducing an object which will contain all these parameters as fields and then, maybe, it'll be possible to apply builder pattern. But still don't have clear vision how to implement that and I'm not sure that it's worth to be done. Any other ideas?

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  • SQL Server Express 2008 Stored Procedure execution time spikes periodically

    - by user156241
    I have a big stored procedure on a SQL Server 2008 Express SP2 database that gets run about every 200 ms. Normal execution time is about 50ms. What I am seeing is large inconsistencies in this run time. It will execute for while, say 50-100 times at 40-60ms which is expected, then seemingly at random the same stored procedure will take way longer, say 900ms or 1.5 seconds to run. Sometimes more than one call of the same procedure in a row will take longer too. It appears that something is causing sql server to slow down dramatically every minute or so, but I can't figure out what. There is no timing pattern between the occurences. I have the same setup on two different computers, one of which is a clean XP Pro load with no virus checking and nothing installed except SQL server. Also, The recovery options for all the databases are set to "Simple".

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