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  • What is the sense of "Feature Oriented Programming" (FOP) in C++, and would it make sense in Java an

    - by ivan_ivanovich_ivanoff
    Hello! Sadly, I can't remember where I read it, but... ...in C++ you can derive a class from a template parameter. Im pretty sure it was called Feature Oriented Programming (FOP) and meant to be somehow useful. It was something like: template <class T> class my_class : T { // some very useful stuff goes here ;) } My questions about this: What is the sense of such pattern? Since this it not possible in Java / C#, how this pattern is achieved in these languages? Can it be expected to be implemented in Java / C# one day? (Well, first Java would need to get rid of type erasure) EDIT: I'm really not talking about generics in Java / C# (where you can't derive a class from a generic type parameter)

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  • Java vs C# - AddActionListener vs event subscription

    - by S.O.
    Very simple question from one somewhat new to Java: when adding an event handler (or whatever it is called in Java) to a Control, MUST it be an object? I mean, in C# I can do control.event += System.eventHandler(methodThatHandlesEvent) Sure, that's because we have delegate types in C#, but I was wondering if I can choose which method would be called when an event is raised in Java? I mean, in Java I can have something like control.AddActionListener(objectWhichClassImplementsActionListener) And then I have the stupid actionPerformed method in this class, which is the only method that is called. I know, there are more kinds of listeners, but I can't have a "ActionListenerHandler" class in which I implement several actionPerformed methods that can be assigned to different controls?

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  • How do develop a Java web application without having to deploy all the time

    - by ChrisSmith..zzZZ
    I've set up a simple Eclipse 3.5/Jetty 6.1 web app which returns hello world. It works. This is on Windows and uses the "Jetty Generic Server Adapter". I have auto deployment working so that it deploys after changes periodically. How do I go about setting it up so that if I change any static content it doesn't have to redeploy i.e I can just hit F5 to see the changes straight away. For minor HTML changes it's quite unusable waiting 20-30 seconds for a deployment.

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  • I want to be able to derive from a class internally, but disallow class in other assemblies to derive from the class

    - by Rokke
    Hej I have the following setup: Assembly 1 public abstract class XX<T> : XX where T: YY { } public abstract class XX {} Assembly 2 public class ZZ : YY {} public class ZZFriend : XX<ZZ> {} I use this feature in reflection when in YY: public class YY { public Type FindFriend { return GetType().Assembly.GetTypes().FirstOrDefault( t => t.BaseType != null && t.BaseType.IsGenericType && typeof(XX).IsAssignableFrom(t) && t.BaseType.GetGenericArguments().FirstOrDefault() == GetType()); } } I would like do disallow inheritance of the non generic class XX like: public class ZZFriend: XX {} Alternatively, I need a method like (that can be used in the reflection in YY.FindFrind()): public Type F(Type t) { return GetTypeThatIsGeneric(XX, Type genericTypeParameter); } That can be used in YY as: Typeof(XX<ZZ) == F(typeof(GetType()) Hope that makes sense... Thanks in advance Søren Rokkedal

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  • In XHR, is it possible to distinguish network errors from cross-origin errors?

    - by greim
    http://www.w3.org/TR/access-control/ Reading the CORS spec linked above, it seems to be the case that it's impossible to reliably distinguish between a generic "network error" and a cross-origin access denied error. From the spec: If there is a network error Apply the network error steps. Perform a resource sharing check. If it returns fail, apply the network error steps. http://www.w3.org/TR/access-control/#simple-cross-origin-request0 In my testing, I couldn't locate any features of Firefox's implementation that seem to indicate that the resource sharing check definitely failed. It just switches readyState to 4 and sets status to 0. Ultimately I'd like the ability to pass a success callback, a general fail callback, and an optional cross-origin fail callback, to my function. Thanks for any help or insight.

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  • Serialized object in intent returning as String

    - by B_
    In my application, I am trying to pass a serializable object through an intent to another activity. The intent is not entirely created by me, it is created and passed through a search suggestion. In the content provider for the search suggestion, the object is created and placed in the SUGGEST_COLUMN_INTENT_EXTRA_DATA column of the MatrixCursor. However, when in the receiving activity I call getIntent().getSerializableExtra(SearchManager.EXTRA_DATA_KEY), the returned object is of type String and I cannot cast it into the original object class. I tried making a parcelable wrapper for my object that calls out.writeSerializable(...) and use that instead but the same thing happened. The string that is returned is like a generic Object toString(), i.e. com.foo.yak.MyAwesomeClass@4350058, so I'm assuming that toString() is being called somewhere where I have no control. Hopefully I'm just missing something simple. Thanks for the help!

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  • How to use pointers and pointer aritmetic

    - by booby
    : error C2064: term does not evaluate to a function taking 1 arguments : error C2227: left of '-name' must point to class/struct/union/generic type how do i fix this so this error doesn't happen for(int index = 0; index < (numStudents); index++) { if (student(index + 1)->score >= 90 ) student(index + 1)->grade = 'A'; else if (student(index + 1)->score >= 80 ) student(index + 1)->grade = 'B'; else if (student(index + 1)->score >= 70 ) student(index + 1)->grade = 'C'; else if (student(index + 1)->score >= 60 ) student(index + 1)->grade = 'D'; else student(index + 1)->grade = 'F'; }

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  • Organize routes in Node.js

    - by NilColor
    Hello! I start to look at Node.js. Aslo I'm using Express. And I have a question - how can I organize web application routes? All examples just put all this app.get/post/put() handlers in app.js and it works just fine. This is good but if I have something more than simple HW Blog? Is it possible to do something like this: var app = express.createServer(); app.get( '/module-a/*', require('./module-a').urls ); app.get( '/module-b/*', require('./module-b').urls ); and // file: module-a.js urls.get('/:id', function(req, res){...}); // <- assuming this is handler for /module-a/1 In other words - I'd like something like Django's URLConf but in Node.js.

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  • Handling a binary operation that makes sense only for part of a hierarchy.

    - by usersmarvin_
    I have a hierarchy, which I'll simplify greatly, of implementations of interface Value. Assume that I have two implementations, NumberValue, and StringValue. There is an average operation which only makes sense for NumberValue, with the signature NumberValue average(NumberValue numberValue){ ... } At some point after creating such variables and using them in various collections, I need to average a collection which I know is only of type NumberValue, there are three possible ways of doing this I think: Very complicated generic signatures which preserve the type info in compile time (what I'm doing now, and results in hard to maintain code) Moving the operation to the Value level, and: throwing an unsupportedOperationException for StringValue, and casting for NumberValue. Casting at the point where I know for sure that I have a NumberValue, using slightly less complicated generics to insure this. Does anybody have any better ideas, or a recommendation on oop best practices?

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  • How to prevent inputting Russian characters in Word with a Word addin?

    - by Edwin
    Hi, Sorry for this vaguely described problem, but please look at the problem from the Win32 API's perspective. I'm writing a Word addin using Addin Express with Delphi, and I use some other 3rd party VCL's also, including virtual stringtree, TNT controls, etc. Now I cannot input Russian characters in Word anymore, but I can input English and Chinese.... Since it's a large project I don't know where to start finding the problem, would you give me some generic tips, I'll be appreciated that! Thank you, and have a nice day!

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  • [C++] Boost test: catch user defined exceptions

    - by user231536
    If I have user defined exceptions in my code, I can't get Boost test to consider them as failures. For example, BOOST_AUTO_TEST_CASE_EXPECTED_FAILURES(MyTest,1) BOOST_AUTO_TEST_CASE(MyTest) { // code which throws user defined exception, not derived from std::exception. } I get a generic message: Caught exception: .... unknown location(0):.... It does not recognize this error as a failure since it is not a std::exception. So it does not honor the expected_failures clause. How do I enforce that the piece of code should always throw an exception? THis seems to be a useful thing to want. In case future code changes cause the code to pass and the exception is not thrown, I want to know that.

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  • How do I cancel a text selection after the initial mousedown event?

    - by cwillu-gmail
    I'm trying to implement a pop-up menu based on a click-and-hold, positioned so that a (really) slow click will still trigger the default action, and with the delay set so that a text-selection gesture won't usually trigger the menu. What I can't seem to do is cancel the text-selection in a way that doesn't prevent text-selection in the first place: returning false from the event handler (or calling $(this).preventDefault()) prevents the user from selecting at all, and the obvious $().trigger('mouseup') doesn't doesn't do anything with the selection at all. This is in the general context of a page, not particular to a textarea or other text field. e.stopPropogation() doesn't cancel text-selection. I'm not looking to prevent text selections, but rather to veto them after some short period of time, if certain conditions are met.

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  • MFC: 'Gluing' two windows/dialogs together

    - by John
    I'm trying to set something up so my main dialog has one or more child dialogs, and these are glued/docked to the outside of the main dialog - when the main dialog is minimised, the children are too, when main dialog moves, children move with it. I'd tried setting child dialogs as having main dialog CWnd as parent, with CHILD style. But then they get clipped by the parent's boundary. If I set them as POPUP, they can be outside but then don't move with the parent. I'm looking at putting an OnMove handler on the parent dialog, but is there something built-in? And, should child dialogs still be children of the main dialog... I assume they should? This is VS2005 (I think VS2008 has some related functionality so I mention this).

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  • Linq to SQL - How to compare against a collection in the where clause?

    - by Sgraffite
    I'd like to compare against an IEnumerable collection in my where clause. Do I need to manually loop through the collection to pull out the column I want to compare against, or is there a generic way to handle this? I want something like this: public IEnumerable<Cookie> GetCookiesForUsers(IEnumerable<User> Users) { var cookies = from c in db.Cookies join uc in db.UserCookies on c.CookieID equals uc.CookieID join u in db.Users on uc.UserID equals u.UserID where u.UserID.Equals(Users.UserID) select c; return cookies.ToList(); } I'm used to using the lambda Linq to SQL syntax, but I decided to try the SQLesque syntax since I was using joins this time. What is a good way to do this?

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  • Accessing facebook sdk result Object using .NET 3.5 API?

    - by John K
    Consider the following in .NET 3.5 (using the Bin\Net35\Facebook*.dll assemblies): using Facebook; var app = new FacebookApp(); var result = app.Get("me"); // want to access result properties with no dynamic ... in the absence of the C# 4.0 dynamic keyword this provides only generic object members. How best should I access the facebook properties of this result object? Are there helper or utility methods or stronger types in the facebook C# SDK, or should I use standard .NET reflection techniques?

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  • Can somebody explain the difference between exceptions and errors (specific to PHP)?

    - by letseatfood
    I am having trouble figuring the best way to display errors to my clients. Should I use exceptions or errors? For example, if the user's login information does not match the database, should I throw new Exception('Login information is incorrect. Please try again.') and catch it with an exception handler using set_exception_handler()? Or, should I use trigger_error() to display an error message to the user? I think the main issue is that I cannot differentiate between errors and exceptions. I have read a lot of "answers" to this question on the internet and in some books, but it seems that people are really divided or aren't sure. Thanks!

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  • Rscript does not recognize setGeneric function

    - by Branko K.
    I am trying to convert an R script into something that a client can run in batch mode. My code uses generic functions and one snippet which is near the beginning goes like: setGeneric("testInput", function(inputData, params = list()) standardGeneric("testInput")) I've been using R CMD BATCH and it works fine. However I couldn't find an easy way to make my script print the output on the console, so based on that (and suggestion that Rscript.exe is the "proper" way to run R batch files) I decided to switch to Rscript. However when running the very same .R file with Rscript I get the following: Error: could not find function "setGeneric" Execution halted I know there is probably a trivial reason behind this but I just cannot figure it out. Can someone please point me to where the mistake is? Thanks so much in advance. Cheers!

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  • Which HRESULT literal constant will fail the SUCCEEDED() macro?

    - by Hamish Grubijan
    Definition of SUCCEEDED(): #define SUCCEEDED(hr) (((HRESULT)(hr)) >= 0) Background: When an Ok button is clicked on a dialog, I need to return an HRESULT value hr such that SUCCEEDED(hr) is true. If Cancel button is clicked, I need to return a negative value. I could have used bools, but that would break the existing pattern (usually the hr values come from depths of system dlls). So, I know I can return S_OK on Ok, but what do I return on Cancel? I could just return (HRESULT)-1;, but there must be a better way - some HRESULT literal constant which has negative value and represents a generic failure. S_FALSE is not it, for it's value is defined as 1L. Please help me find the right constant.

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  • How to get the app a Django model is from?

    - by e-satis
    I have a model with a generic relation: TrackedItem --- genericrelation ---> any model I would like to be able to generically get, from the initial model, the tracked item. I should be able to do it on any model without modifying it. To do that I need to get the content type and the object id. Getting the object id is easy since I have the model instance, but getting the content type is not: ContentType.object.filter requires the model (which is just content_object.__class__.__name__) and the app_label. I have no idea of how to get in a reliable way the app in which a model is. For now I do app = content_object.__module__.split(".")[0], but it doesn't work with django contrib apps.

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  • When should one let an application crash because of an exception in Java (design issue)?

    - by JVerstry
    In most cases, it is possible to catch exceptions in Java, even unchecked ones. But, it is not necessarily possible to do something about it (for example out of memory). For other cases, the issue I am trying to solve is a design principle one. I am trying to set-up a design principle or a set of rules indicating when one should give up on an exceptional situation, even if it is detected in time. The objective is trying to not crash the application as much as possible. Has someone already brainstormed and communicated about this? I am looking for specific generic cases and possible solutions, or thumb-rules. UPDATE Suggestions so far: Stop running if data coherency can be compromised Stop running if data can be deleted Stop running if you can't do anything about it (Out of memory...) Stop running if key service is not available or becomes unavailable and cannot be restarted If application must be stopped, degrade as gracefully as possible Use rollbacks in db transactions Log as much relevant information as you can Notify the developers

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  • How to inherit methods from a parent class in C++

    - by Pat
    When inheriting classes in C++ I understand members are inherited. But how does one inherit the methods as well? For example, in the below code, I'd like the method "getValues" to be accessible not through just CPoly, but also by any class that inherits it. So one can call "getValues" on CRect directly. class CPoly { private: int width, height; public: void getValues (int* a, int* b) { *a=width; *b=height;} }; class CRect: public CPoly { public: int area () { return (width * height); } }; In other words, is there any way to inherit methods for simple generic methods like getters and setters?

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  • Assigning data to an <li> element?

    - by user246114
    Hi, I am generating some list items as a result of a search, and I want to attach some data to each list element from the search (possibly a bad idea to merge ui and data), but now curious about it. I am doing this: var element = $("<li>Hello</li>); element.mydata = "foo"; element.appendTo("#panelParent"); so I'm just assigning my stuff to element.mydata. My click handler reports that no such data exists for the element when clicked: $('#panelParent').delegate('li', 'click', function() { // this.mydata is undefined. }); where did it go to? I could keep the data external to the a list item element, was wondering if there's a convenient way like this to just keep it bound though? Thanks

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  • Is there a way to load multiple app.configs in memory?

    - by Dave
    I have a windows service that loads multiple "handlers" written by different developers. The windows service exe has it's own app.config which I need. I'm trying to make it so that each developer can provide their own app.config along with their handler code. However, it seems an exe can only have one app.config. However, ASP.NET seems to support nested web.config... That's not exactly what I want, but I don't even know how I would get that to work in a windows service. Anyone come across this before or have any ideas?

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  • Why can I check some event handlers for null, some not?

    - by Inno
    Hi, I have a ugly piece of code that adds event handlers. The problem is, if the code is called multiple times, the event handlers are called multiple times. To solve the problem, I remove the event handler first and then add it. Now I've seen the following behaviour: Some event handlers can be checked like: if (object.event == null) { // // Code // } others of the form if (object.object.event == null) { // // Code // } I get a message like 'object.object.event' may only occur left of -= or +=. (Since I'm using a german version of visual studio, I don't know the correct translation to english). I have no idea why the behaviour looks this inconsequent so I would be grateful for some information on this. To be more specific: It's user control. if (myControl.Event == null) { // // works // } if (myControl.TreeView.NodeMouseClick == null) { // // doesn't work // }

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  • Robust way to display an image with one fixed dimension

    - by DomingoSL
    Lets say that we have an image uploaded by the user, the upload script limits the mb but not the image size (so could be any proportion, 600X200,200X350, and so...). Im already showing this image in one part on my site using the twitter bootstrap image handler written on css, thats good for a profile picture, the problem is that now I want that image to be a cover (like facebook/twitter cover image), my site is responsive so the width of the cover is 900px or 100% if the screen resolution is less than 900px wide. The height is always fixed to 200px. So I know there is a way to control the correct image display using CSS (maybe with jquery too) but Im not a front-end dev, Im a php dev and I dont want to use server side scripts for doing this. So im looking for suggestions or pieces of codes (css, javascript) to start with, I belive that it have to be an already made solution for this, but I dont find any on google. Thanks for any advice!

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