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• How to code for Alternate Course AKA Rainy Day Scenary?

  - by janetsmith

  Alternate course is something when user doesn't do what you expected, e.g. key in wrong password, pressing back button, or database error. For any programming project, alternate course accounts for more than 50% of a project timeline. It is important. However, most computer books only focus on Basic Course (when everything goes fine). Basic course is rather simple, compared to Alternate course, because this is normally given by client. Alternate course is what we, as a programmer or Business Analyst needs to take care of. Java has some built-in mechanism (try-catch) to force us to handle those unexpected behavior. The question is, how to handle them? Any pattern to follow? Any guideline or industry practice for handling alternate course?

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• Embed external images for use in HTML canvas?

  - by Philipp Lenssen

  I'm using JavaScript to load an image into my Canvas element in Firefox. This works fine for local images, but throws a security exception for external images. Is there any way to avoid this security exception, one that does not involve my server having to act as proxy to load the image locally (because that would stress my server)? PS: The current code is similar to this: var img = new Image(); var contextSource = canvasSource.getContext('2d'); contextSource.drawImage(img, 0, 0); // get image data to do stuff with pixels var imageDataSource = contextSource.getImageData(0, 0, width - 1, height - 1);

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• Accessing database problem

  - by anarche

  Ok, so I've got an SQLiteOpenHelper that prepares and returns a SQLiteDatabase object; this is written singleton-pattern, so the database is opened once and only closed when the Activity closes. From there I have three database wrappers encapsulating the queries (some returning cursors to datasets, some inserting data) used by the Activity. I want to insert data from one View, then have that automatically update in another View on the same Dialogue. I'm writing this on a notepad and testing on the phone (since the emulator crashes the notepad...), so I can't pull up stacktraces atm. So questions: 1) are there limitations to writing to a database, when there are cursors open on the database? 2) Does a Cursor.requery()? call update the ListView with the cursor as a data connector?

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• Partitioning requests in code among several servers

  - by Jacques René Mesrine

  I have several forum servers (what they are is irrelevant) which stores posts from users and I want to be able to partition requests among these servers. I'm currently leaning towards partitioning them by geographic location. To improve the locality of data, users will be separated into regions e.g. North America, South America and so on. Is there any design pattern on how to implement the function that maps the partioning property to the server, so that this piece of code has high availability and would not become a single point of failure ? f( Region ) -> Server IP

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• Looking for a good explanation of the table generation macro idiom

  - by detly

  I want to make this clear up front : I know how this trick works, what I want is a link to a clear explanation to share with others. One of the answers to a C macro question talks about the "X macro" or "not yet defined macro" idiom. This involves defining something like: #define MAGIC_LIST \ X(name_1, default_1) \ X(name_2, default_2) \ ... Then to create, say, an array of values with named indices you do: typedef enum { #define X(name, val) name, MAGIC_LIST #undef X } NamedDefaults; You can repeat the procedure with a different #define for X() to create an array of values, and maybe debugging strings, etc. I'd like a link to a clear explanation of how this works, pitched at someone who is passably familiar with C. I have no idea what everyone usually calls this pattern, though, so my attempts to search the web for it have failed thus far. (If there is such an explanation on SO, that'd be fine...)

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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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• Strategies for generating Zend Cache Keys

  - by emeraldjava

  ATM i'm manually generating a cache key based on the method name and parameters, then follow to the normal cache pattern. This is all done in the Controller and i'm calling a model class that 'extends Zend_Db_Table_Abstract'. public function indexAction() { $cache = Zend_Registry::get('cache'); $individualleaguekey = sprintf("getIndividualLeague_%d_%s",$leagueid,$division->code); if(!$leaguetable = $cache->load($individualleaguekey)) { $table = new Model_DbTable_Raceresult(); $leaguetable = $table->getIndividualLeague($leagueid,$division,$races); $cache->save($leaguetable, $individualleaguekey); } $this->view->leaguetable = $leaguetable; .... I want to avoid the duplication of parameters to the cache creation method and also to the model method, so i'm thinking of moving the caching logic away from my controller class and into model class packaged in './model/DbTable', but this seems incorrect since the DB model should only handle SQL operations. Any suggestions on how i can implement a clean patterned solution?

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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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• How to disable UI control based on domain object's state?

  - by Subb

  Here's my problem. I have a somewhat complex domain object, which, depending on its state, responds to certain actions. I think the state pattern is pretty much the solution for that. However, I need to display which actions are possible at any moment in the UI. Ex: The domain object is an audio player. Some songs can't be skipped (like ads), so I need to disable the "next" and "previous" buttons in the GUI so the user have some kind of feedback of which action he can execute. I've looked at Swing's Action class (note: this is not a Java project), but I think I would need to keep every Actions in my domain object class (audio player), so it can enable or disable them depending on its own state (thus, affecting the UI). Is it the way to do it?

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• Can we you the attached properties in C# class library?

  - by Manas Agarwal

  Hi I have implemented the Observer Pattern with lazy load. The class that requests the data from the database is a singleton class. Now I am able to load the data from one database (located in one datacenter) very easily. But I need to get the data from other data centers too and display on the same UI. I can somehow pass the address of second data center and fetch the data from there also. But once I will get the data from second data center, it will be added to earlier list only. So later it will be thought for me to distinguish between the data. So I thought of attaching a property with the result set, so that while displaying the output I can show the data for both the data centers separately but on the same UI. I thought of attached property as an option where I can attach the data center name with the list of the data obtained. How is it possible to do in C#? Thanks Manas

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• Favoriting system on Appengine

  - by Mateusz Cieslak

  Hi, I have the following model structure class Authors(db.Model) : nickname = db.StringProperty(required=True) fullname = db.StringProperty(required=True) class Articles(db.Model) : title = db.StringProperty(required=True) body = db.StringProperty(required=True) author = db.ReferenceProperty(Authors, required=True) class Favorites(db.Model) : who = db.ReferenceProperty(Authors, required=True) what = db.ReferenceProperty(Articles, required=True) I'd like to display 10 last articles according to this pattern: article.title, article.body, article.author(nickname), info if this article has been already favorited by the signed in user. I have added a function which I use to get the authors of these articles using only one query (it is described here) But I don't know what to do with the favorites (I'd like to know which of the displayed articles have been favorited by me using less than 10 queries (I want to display 10 articles)). Is it possible?

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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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• 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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• 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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• what is the return value of BeautifulSoup.find ?

  - by prosseek

  I run to get some value as score. score = soup.find('div', attrs={'class' : 'summarycount'}) I run 'print score' to get as follows. <div class=\"summarycount\">524</div> I need to extract the number part. I used re module but failed. m = re.search("[^\d]+(\d+)", score) TypeError: expected string or buffer function search in re.py at line 142 return _compile(pattern, flags).search(string) What's the return type of the find function? How to get the number from the score variable? Is there any easy way to let BeautifulSoup to return the value(in this case 524) itself?

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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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• php regex replace slashes and spaces and hyphens

  - by Muhammad Shahzad

  I have fews combinations of strings that I need to bring in to one pattern, that is multiple spaces should be removed, double hyphens should be replaced with single hypen, and single space should be replaced with single hyphen. I have already tried this expression. $output = preg_replace( "/[^[:space:]a-z0-9]/e", "", $output ); $output = trim( $output ); $output = preg_replace( '/\s+/', '-', $output ); But this fails in few combinations. I need help in making all of these combinations to work perfectly: steel-black steel- black steel black I should also remove any of these as well "\r\n\t".

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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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• string parsing help

  - by sprugman

  I've got a string like this: #################### Section One #################### Data A Data B #################### Section Two #################### Data C Data D etc. I want to parse it into something like: $arr( 'Section One' => array('Data A', 'Data B'), 'Section Two' => array('Data C', 'Data D') ) At first I tried this: $sections = preg_split("/(\r?\n)(\r?\n)#/", $file_content); The problem is, the file isn't perfectly clean: sometimes there are different numbers of blank lines between the sections, or blank spaces between data rows. The section head pattern itself seems to be relatively consistent: #################### Section Title #################### The number of #'s is probably consistent, but I don't want to count on it. The white space on the title line is pretty random. Once I have it split into sections, I think it'll be pretty straightforward, but any help writing a killer reg ex to get it there would be appreciated. (Or if there's a better approach than reg ex...)

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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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• Implementing Qt File Dialog with a Different File System Library (boost)

  - by knight

  Hi, I am writing an application which requires me to use another file system and file engine handlers and not the qt's default ones. Basically what I want to be able to do is to use qt's file dialog but have an underlying file system handler (for example built using boost file system library) of mine handling all the operations with regards to file and directory operations within that dialog. I have already written a custom file engine which handles some of the operations but I am now stuck with Qt's file system model and the file system watcher engine, as I need to have the signals transmitted for this custom file engine. Seems like I have a daunting task ahead. Am I heading in the right direction? Is there any other simpler way that I could implement this? Can anyone give me any idea on how to proceed. I was thinking of looking into proxy models but not sure if that would work. Thanks in advance for any help.

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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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• Accessing Securised Web Service

  - by Xstahef

  Hi, I need to connect to a provider's web service with a Windows Form application. He gives me a certificate to access it but I have a security problem. I have done these following steps : Add certificate to personal store (on IE & Firefox) Generate a proxy with the remote wsdl (no problem) Use this code to call a method : `using (service1.MessagesService m = new service1.MessagesService()) { X509Certificate crt = new X509Certificate(@"C:\OpenSSL\bin\thecert.p12",string.Empty); m.ClientCertificates.Add(crt); var result = m.AuthoriseTransaction(aut); this.textBox1.AppendText(result.id.ToString()); }` I have the following error : The underlying connection was closed: Could not establish trust relationship for the channel SSL / TLS. Thanks for your help

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• a problem in socket programing in perl

  - by isu

  I write this code : #!/usr/local/bin/perl use strict; use LWP::UserAgent; my $ua = new LWP::UserAgent(agent => 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.5) Gecko/20060719 Firefox/1.5.0.5'); $ua->proxy([qw(http https)] => 'http://203.185.28.228:1080' #that is just socks:port); my $response = $ua->get("http://www.google.com"); print $response->code,' ', $response->message,"\n"; but when i execute it i get this error: 500 Can't connect to 203.185.28.228:1080 (connect: timeout) what am i going to do ?

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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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