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  • Instantiation vs. Typed reference

    - by Farstucker
    Just when I think Im starting to understand the basics, I find something that brings me right back to reality. In this case, typed reference. I found an example similar to this: class Worker { Boss boss; public void Advise(Boss pBoss) { this.boss = pBoss; } How can you reference methods within the Boss class if its not static and not instantiated? I guess my real question is whats the difference between: Boss boss; and Boss boss = new Boss(); Thank you, FS

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  • What is the best method of assessment for computer science students?

    - by Gavimoss
    This question is a bit more philosophical so feel free to remove if you like but it's been bugging me for the last 4 years! As a final year student I find that exams can be often be passed with a couple of days of cramming, without necessarily retaining or understanding the content i.e. a regurgitation of lecture notes is often enough to gain high marks. A friend of mine is about to graduate with an honours degree whose final year evaluation was based solely on practical work (a project, assignment marks and the creation of a poster) yet all of this work could have been completed by a third party. Personally I don't think either of these methods of assessment is sufficient as I am currently on track for a 1st class honours in artificial intelligence and computer science and believe this is mostly due to my skill in passing exams not my skill as a programmer or my vast in depth knowledge of any of the subjects I have "studied". Surely there is a better way to assess our skills - isn't there?

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  • Fastest/One-liner way to list attr_accessors in Ruby?

    - by viatropos
    What's the shortest, one-liner way to list all methods defined with attr_accessor? I would like to make it so, if I have a class MyBaseClass, anything that extends that, I can get the attr_accessor's defined in the subclasses. Something like this: class MyBaseClass < Hash def attributes # ?? end end class SubClass < MyBaseClass attr_accessor :id, :title, :body end puts SubClass.new.attributes.inspect #=> [id, title, body] What about to display just the attr_reader and attr_writer definitions?

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  • How do I combine similar method calls into a delegate pattern?

    - by Daniel T.
    I have three methods: public void Save<T>(T entity) { using (new Transaction()) { Session.Save(entity); } } public void Create<T>(T entity) { using (new Transaction()) { Session.Create(entity); } } public void Delete<T>(T entity) { using (new Transaction()) { Session.Delete(entity); } } As you can see, the only thing that differs is the method call inside the using block. How can I rewrite this so it's something like this instead: public void Save<T>(T entity) { TransactionWrapper(Session.Save(entity)); } public void Create<T>(T entity) { TransactionWrapper(Session.Create(entity)); } public void Save<T>(T entity) { TransactionWrapper(Session.Save(entity)); } So in other words, I pass a method call as a parameter, and the TransactionWrapper method wraps a transaction around the method call.

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  • [PHP] Processing custom XML namespace within XSL

    - by sander
    I'm using the php class XSLTProcessor to generate HTML from a xsl. Within the xsl, I'd like all my custom namespace elements to be processed by my own processor class. So for example: <xsl:for-each select="doc/elements/*"> <doc:renderElement element="." /> </xsl:for-each> This should call the method renderElement of an instance of my custom processor class. I know I can enable calling php functions by using the registerPHPFunctions function. However, this only seems to support calling static methods.

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  • Which would be better? Storing/access data in a local text file, or in a database?

    - by TerranRich
    Basically, I'm still working on a puzzle-related website (micro-site really), and I'm making a tool that lets you input a word pattern (e.g. "r??n") and get all the matching words (in this case: rain, rein, ruin, etc.). Should I store the words in local text files (such as words5.txt, which would have a return-delimited list of 5-letter words), or in a database (such as the table Words5, which would again store 5-letter words)? I'm looking at the problem in terms of data retrieval speeds and CPU server load. I could definitely try it both ways and record the times taken for several runs with both methods, but I'd rather hear it from people who might have had experience with this. Which method is generally better overall?

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  • How do I attach an event handler to the document or window in GWT?

    - by Raph Levien
    In a GWT app centered around a canvas, I'm having trouble keeping focus directed in the right place - particularly for keyboard shortcuts. For now, I've wrapped the canvas in a FocusPanel, but that causes the canvas to not respond to the RequiresResize protocol, because FocusPanel does not plumb that. A second (related, I think) problem is that the FocusPanel is not getting Ctrl-A keypress events at all (tested on Mac Chrome). I can get Ctrl-Z and other keys (such as arrows) just fine. In a pure JavaScript world, I think the best answer to this would be to attach mouse and key handlers to the document or window object (I'm not positive which is better). However, I don't see an obvious way to do this in GWT - in particular, the Document and Window classes lack methods for attaching these kind of event handlers? Anyone know how to do it, or, perhaps, to solve the more general problem of keeping focus on an appropriate widget able to handle keyboard shortcuts?

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  • PHPUnit test for error thrown with wrong argument type

    - by Spencer Mark
    I'm just starting with PHPUnit and am ok with all assert* methods, but can't figure out how to test for error thrown when the wrong argument is provided to the method - say hinted with array like so: public function(array $list) { } and then tested with null as argument. Could someone please provide an example of how to test for this sort of errors? I've checked quite a few posts on stackoverflow, but couldn't find the answer to this specific issue. Edit Ok - just to give you an idea of what I'm testing - here's the ArrayHelper::removeIfValueIsEmpty() method: public static function removeIfValueIsEmpty(array $array) { if (empty($array)) { return array(); } return array_filter($array, function($value) { return !Helper::isEmpty($value); }); } and now test: class ArrayHelperTest extends PHPUnit_Framework_TestCase { public function testRemoveIfValueIsEmpty() { $this->assertEmpty( \Cmd\Helper\ArrayHelper::removeIfValueIsEmpty(null), '\Cmd\Helper\ArrayHelper::removeIfValueIsEmpty method failed (checking with null as argument)' ); } } This throws an error: PHPUnit_Framework_Error : Argument 1 passed to Cmd\Helper\ArrayHelper::removeIfValueIsEmpty() must be of the type array, null given

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  • Could not able to register the third party DLL using regsvr32

    - by Mahadev Malkar
    i have been trying to register the third party dll file using the regsvr32 command, but it keeps giving me the error that 'the dll doesn't have a entry point, dll could not be registered'. Is it possible to register the dll and use it as a COM component in .NET ? Or I want to use that dll as a COM component in c#.NET. Is there any way to use that dll as COM Component. When i tried to use it as COM component, the dll file, its methods, interfaces are visible in .NET. but when i tried to use any of that interface it gives me error as 'Retrieving the COM class factory for component with CLSID {C4CC4F47-2AF6-41FA-A43D-01E8B3050D3F} failed due to the following error: 80040154.'. Plz tell me any solution.

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  • iphone threading speed up startup of app

    - by BahaiResearch.com
    I have an app that must get data from the Sqlite database in order to display the first element to the User. I have created a domain object which wraps the DB access and is a thread safe singleton. Is this following strategy optimal to ensure the fastest load given the iPhone's file access and memory management capabilities in threaded apps: 1) In the AppDelegate's FinishedLaunching event the very first thing I do is create the domain singleton within a new thread. This will cause the domain object to go to Sqlite and get the data it needs without locking the UI thread. 2) I then call the standard Window methods to add the View and MakeKeyAndVisible etc. Is there an earlier stage in the AppDelegate where I should fire off the thread that creates the Domain Object and accesses Sqlite?

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  • Create a select tag with some options grouped and others not grouped

    - by dontangg
    I'm using Rails 3. I want to create a select tag with some options grouped and others not grouped. Options would look something like this: Income Auto Fuel Maintenance Home Maintenance Mortgage In this example, Income is not a group, but Auto and Home are. I see three helper methods grouped_options_for_select and grouped_collection_select, option_groups_from_collection_for_select. Is there a way to use a helper to do this or will I have to generate the HTML myself? I imagine I could use two different helpers to create the options and just append the results of both.

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  • Best approach to creating a database driven Java website?

    - by Craig Whitley
    I'm fairly new to programming and new to java, but I'd like to jump in the deep end with a little database driven website project. I've read quite a lot about requirements in the 'real world' requesting experience with Spring and Hibernate, so I have those installed on netbeans and a project created (if I hit run I get the default spring page). Now I just need a little guidance as to where to start designing my app (please tell me if I'm getting in a bit too over my head for a beginner!). Should I start off with my classes? - create all my classes as they map to my database tables and decide which attributes and methods each will require? Can anyone suggest any good books for maybe.. making a java based website from scratch (i.e. from design right through to deployment) that might be useful for a beginner? Any help appreciated thanks.

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  • Creating an interface and swappable implementations in python

    - by Blankman
    Hi, Would it be possible to create a class interface in python and various implementations of the interface. Example: I want to create a class for pop3 access (and all methods etc.). If I go with a commercial component, I want to wrap it to adhere to a contract. In the future, if I want to use another component or code my own, I want to be able to swap things out and not have things very tightly coupled. Possible? I'm new to python.

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  • Is it ok to store large objects (java component for example) in an Application variable?

    - by DustMason
    I am developing an app right now which creates and stores a connection to a local XMPP server in the Application scope. The connection methods are stored in a cfc that makes sure the Application.XMPPConnection is connected and authorized each time it is used, and makes use of the connection to send live events to users. As far as I can tell, this is working fine. BUT it hasn't been tested under any kind of stress. My question is: Will this set up cause problems later on? I only ask because I can't find evidence of other people using Application variables in this way. If I weren't using railo I would be using CF's event gateway instead to accomplish the same task.

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  • Why do I have to explicitly cast sometimes for varargs?

    - by Daniel Lew
    I've got a Class that uses reflection a lot, so I wrote a method to help out: private <T> T callMethod(String methodName, Class[] parameterTypes, Object[] args) { try { Class c = mVar.getClass(); Method m = c.getMethod(methodName, (Class[]) parameterTypes); return (T) m.invoke(mVar, args); } // Insert exception catching here [...] } This worked well for any method that had parameters, however I had to explicitly cast parameterTypes to Class[] in order for this to work for methods with no parameters (e.g., callMethod('funName', null, null);). I've been trying to figure out why this is the case. It seems to me that if parameterTypes, when null, had no concept of what type it is (Class[]), then I'd need to cast it for getMethod(). But if that's the case, why is getMethod() able to tell the difference between null, and (Class[]) null when the method is invoked?

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  • In java can i have more than one class/object in a file?

    - by David
    So the way i've been told to do things is you have your file and the file name is Classname.java and then the code is something like this: class ClassName { SOME METHODS main {} } and then thats all. I'd like to have two objects defined and used within the same .java file. (i don't want to have to put the other class in a difernt file just because i'd like to send this to someone and i want to avoid hasstle of atatching multiple files to an email [the lazy do make good programers though if you think about it]) is it possible to do this? do i have to do anything special and if so what? what are some mistakes i'm likely to make or that you have made in the past when doing this?

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  • One configuration per domain name on the same application. How to easily access config values from m

    - by Aymeric
    Hi, I run a Ruby on Rails website that have multiple domain names. I have a "Website" table in the database that stores the configuration values related to each domain name: Website - domain - name - tagline - admin_email - etc... At the moment, I load the website object at the start of each request (before_filter) in my ApplicationController: @website = Website.find_by_domain(request.host) The problem is when I need to access the @website object from my models methods. I would like to avoid to have to pass @website everywhere. The best solution would be to have something similar to APP_CONFIG but per domain name. def sample_model_property - - "#{@website.name} is a great website!" end How would you do it?

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  • C++ Word-Number to int

    - by Andrew
    I'm developing a program that makes basic calculations using words instead of numbers. E.g. five + two would output seven. The program becomes more complex, taking input such as two_hundred_one + five_thousand_six (201 + 5006) Through operator overloading methods, I split each number and assign it to it's own array index. two would be [0], hundred is [1], and one is [2]. Then the array recycles for 5006. My problem is, to perform the actual calculation, I need to convert the words stored in the array to actual integers. I have const string arrays such as this as a library of the words: const string units[] = { "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; const string teens[] = { "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" }; const string tens[] = { "", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" }; If my 'token' array has stored in it two hundred one in index 0, 1, and 2, I'm not sure what the best way to convert these to ints would involve.

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  • Losing scope for DataContex using LINQToSQL intermediately

    - by greektreat
    I am having a weird Situation with my DataConext. All My code is in C# I have a DLL project for my data access layer and business Layer which and Winforms project for my UI layer. My Data access Layer's Namespace is xxx.Data this is where have my xxx.dbml I also have xxx.Data.BusinessObjects name space of course for my business object in that project In my UI Layer I have these namespaces xxxApp(for Forms), xxxApp.Controls (For Controls) I have lost scope of the DataContext, it was accessible now when I do a Rebuild Solution I sometimes get compile errors saying for example: Error 34 'xxx.Data.xxxDataContext' does not contain a definition for 'SubmitChanges' and no extension method 'SubmitChanges' accepting a first argument of type 'xxx.Data.xxxDataContext' could be found (are you missing a using directive or an assembly reference?) Also intelisense doesn't recognize the methods and table classes from my xxxDataContext anymore I can access all object fine when I am in the DLL project but now in the Winforms project this is very strange. If anyone can help me out I would be extremely grateful!

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  • Serializing System.Drawing.Color in .NET

    - by alankdkd
    Hi all, I've used the default .NET serialization for a class with a System.Drawing.Color member. The code is now in use by people, and I need to add an extra member to the class, but still deserialize older versions. So I tried the standard way of doing this: The ISerializable interface, using SerializationInfo methods to get the int and string members. The problem: My class also has a System.Drawing.Color member, but SerializationInfo doesn't provide a "GetColor" method read this data type. I've tried getting it as an int and as a string, and casting it to System.Drawing.Color, but no luck. Does anyone know how to deserialize a System.Drawing.Color from SerializationInfo? Thanx! Alan

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  • AJAX XMLHttpRequest POST X-Domain

    - by Tom
    Hi Guys, I am sending an AJAX request using POST over X-Domain for a widget we are producing for our website. The problem we are facing is that this is getting blocked. My question is - for "modern browsers" [Chrome, Safari, FF, IE8] - it is my understanding that setting "Access-Control" headers Access-Control-Allow-Origin: http://www.test.com Access-Control-Allow-Methods: POST, GET, OPTIONS Access-Control-Allow-Headers: * Access-Control-Max-Age: 1728000 Will allow these "POST" requests to work ? But for IE7 we need to implement some "custom" JSONP solution? Am I correct in this ?

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  • Difference between var and Class class in object creation

    - by Divine
    Its a silly question, however shocked to see different behaviors. Learning a lot. Lets say I have two classes below Class A { public void Display() { } } Class B : A { public void Display() { } } Class C : B { public void Display() { } } Class Final { static void Main() { var c = new C(); // B c = new C(); //My doubt is, both of the above gives different results. May I know B c = new C() creates object of B or C? What I understood is, it creates object of B. Then why we say "new C()"? I agree with C c = new C(); But I thought, B b = new C(); creates object of B. Where we use this style? Only when utilizing runtime polymorphism? (Overriding methods)? } }

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  • ArrayBlockingQueue exceeds given capacity

    - by Wojciech Reszelewski
    I've written program solving bounded producer & consumer problem. While constructing ArrayBlockingQueue I defined capacity 100. I'm using methods take and put inside threads. And I've noticed that sometimes I see put 102 times with any take's between them. Why does it happen? Producer run method: public void run() { Object e = new Object(); while(true) { try { queue.put(e); } catch (InterruptedException w) { System.out.println("Oj, nie wyszlo, nie bij"); } System.out.println("Element added"); } } Consumer run method: public void run() { while(true) { try { queue.take(); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Element removed"); } } Part of uniq -c on file with output: 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 2 Element removed 2 Element added 102 Element removed 102 Element added

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  • How to provide an API client with 1,000,000 database results?

    - by Chris Dutrow
    What is a good way to provide an API client with 1,000,000 database results? We are cureently using PostgreSQL. A few suggested methods: Paging using Cursors Paging using random numbers ( Add "GREATER THAN ORDER BY " to each query ) Save information to a file and let the client download it Iterate through results, then POST the data to the client server Return only keys to the client, then let the client request the objects from Cloud files like Amazon S3 (still may require paging just to get the file names ). What haven't I thought of that is stupidly simple and way better than any of these options?

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  • Securing an ajax request

    - by asdasdsa
    i have a website that uses session cookies for security. it works fine and all, but any ajax requests right now are not secure. example being lets say a user is on a page. they can only get to this page if they are logged in with a session - so far so good. but now the ajax request they ask for is ajaxpages/somepage.php?somevar=something&anothervar=something if any other user decides to just go to that link themselves (without a session) they still get the same ajax output that was meant for logged in people. so obviously im going to have to pass session data across when i send an ajax request. anyone have any tips for the best way of doing this? ive never done this before and would rather use trusted methods than make up my own.

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