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• Cast vector<T> to vector<const T>

  - by user345386

  I have a member variable of type vector (where is T is a custom class, but it could be int as well.) I have a function from which I want to return a pointer to this vector, but I don't want the caller to be able to change the vector or it's items. So I want the return type to be const vector* None of the casting methods I tried worked. The compiler keeps complaining that T is not compatible with const T. Here's some code that demonstrates the gist of what I'm trying to do; vector<int> a; const vector<const int>* b = (const vector<const int>* ) (&a); This code doesn't compile for me. Thanks in advance!

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• creating events in my classes, and allowing others to hook into them in my django app

  - by Blankman

  I want to create events for my classes. Say I create a CMS application that has a Article object. I create events like: OnEdit OnCreate OnDelete PreCreate PreDelete Now I want someone to be able to hook into these events, and add their custom functionality at each event they wish. I don't want them touching the core source code, so they would have to wire these custom methods to fire somewhere else. I'm new to both python and django so please be as detailed as possible if you can.

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• Speed of interpolation algorithms, C# and C++ working together.

  - by Kaminari

  Hello. I need fast implementation of popular interpolation algorithms. I figured it out that C# in such simple algorithms will be much slower than C++ so i think of writing some native code and using it in my C# GUI. First of all i run some tests and few operations on 1024x1024x3 matrix took 32ms in C# and 4ms in C++ and that's what i basicly need. Interpolation however is not a good word because i need them only for downscaling. But the question is: Will it be faster than C# methods in Drawing2D Image outputImage = new Bitmap(destWidth, destHeight, PixelFormat.Format24bppRgb); Graphics grPhoto = Graphics.FromImage(outputImage); grPhoto.InterpolationMode = InterpolationMode.*; //all of them grPhoto.DrawImage(bmp, new Rectangle(0, 0, destWidth, destHeight), Rectangle(0, 0, sourceWidth, sourceHeight), GraphicsUnit.Pixel); grPhoto.Dispose(); Some of these method run in 20ms and some in 80. Is there a way to do it faster?

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• Delphi 2010 - Why can't I declare an abstract method with a generic type parameter?

  - by James

  I am trying to do the following in Delphi 2010: TDataConverter = class abstract public function Convert<T>(const AData: T): string; virtual; abstract; end; However, I keep getting the following compiler error: E2533 Virtual, dynamic and message methods cannot have type parameters I don't quite understand the reason why I can't do this. I can do this in C# e.g. public abstract class DataConverter { public abstract string Convert<T>(T data); } Anyone know the reasoning behind this?

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• Why is this consider bad practice? or is it? (ASP.Net)

  - by user318573

  Would this code be considered bad practice: <div id="sidebar"> <% =DisplayMeetings(12) %> </div> This is a snippet of code from the default.aspx of a small web app I have worked on. It works perfectly well, runs very fast, but as always, I am aware of the fact that just because it works, doesn't mean it is OK. Basically, the DisplayMeetings subroutine outputs a bunch of formatted HTML (an unordered list actually), with no formatting, just the requisite html, and then my CSS performs all the necessary formatting. The data for generating the list comes from an SQL server database (the parameter controls how many rows to return) and I am using stored procedures and datareader for fast access. This keeps my front-end extraordinary simple and clean, imho, and lets me do all the work in VB or C# in a separate module. I could of course use a databound repeater (and probably 6 or more other methods) of accomplishing the same thing, but are they any better? Other than loosing the design-time features of VS2010?

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• ASP.net and WCF some clarification

  - by nettguy

  Recently I faced few interview questions.The interviewer asked the to give the detailed answer. 1)Can we override a WCF service (Its is not OOPS overriding) ?.Explain the reason on either end. (WCF Related). 2)Can we override Page events (Page_Load())?.Explain reason.(ASP.NET related). 3)What is the primary responsibility of Pre_Init( page) event ,apart from user preference setting,skinning? 4) Can we override Static methods.Explain the reason. can anyone help me to understand the reasons.Thanks in well advance.

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• C# SQL SELECT Statement

  - by Feren6

  I have the following code: SqlCommand cmd2 = new SqlCommand("SELECT ClaimId FROM tblPayment WHERE PaymentId = " + PaymentID.ToString(), mvarDBConn); SqlDataReader reader = cmd2.ExecuteReader(); reader.Read(); Int32 ClaimId = reader.GetInt32(0); reader.Close(); If I run the SELECT statement in SQL it returns the number fine, but when I use ExecuteReader all it returns is 0. I've tried multiple methods including ExecuteScalar, ExecuteNonQuery, reader.GetString then casting that to an int, etc. What am I missing? Thanks.

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• Why is it possible to save entity but not delete if transactional annotation is set to readonly=true

  - by jakob

  Hello experts! My class is annotated with org.springframework.transaction.annotation.Transactional like this: @Transactional(readOnly = true) public class MyClass { I then have a dao class: @Override public void delete(final E entity) { getSession().delete(entity); } @Override public void save(final E entity) { getSession().saveOrUpdate(entity); } Then I have two methods in MyClass @Transactional(readOnly = false) public void doDelete(Entity entity){ daoImpl.delete(entity) } //@Transactional(readOnly = false) public void doSave(){ daoImpl.save(entity) } Saving and deleting works like a charm. But if I remove the @Transactional(readOnly = false) on doDelete method deletion stops working, Saving works with and without the method annotation. So my question is: WHY?

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• Many-to-many relationship in oop

  - by Manu

  what is best way to model many-to-many relationship? lets say we have a two classes , Team and Player any given Player can be in multiple Team s any Team can have as many Player s as they like I like to call methods like playerX.getTeamList() to get the list of all the Team s he/she is in teamY.getPlayerList() to get the list of all the Player s in the team (or have some other way to do this effectively) I can think of two ways of doing this , but they just don't feels like good oop pattens. can you think of any good ways , perhaps a design patten ?

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• Replace <Unknown Source> in Java Rhino (JSR223) with actual file name

  - by Lord.Quackstar

  Hello everyone, In my code, all of the scripts are contained in .js files. Whenever one of the scripts contains an error, I get this: javax.script.ScriptException: sun.org.mozilla.javascript.internal.EcmaError: ReferenceError: "nonexistant" is not defined. (<Unknown source>#5) in <Unknown source> at line number 5 What bugs me is the <Unknown Source>. Multiple files are in one ScriptContext, and it can be hard to track down an error. It also looks horrible. Is there a way to replace <Unknown Source> with the actual file name? None of the methods I see support passing a File object, so I'm really confused here.

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• Django: Inject errors into already validated form?

  - by Parand

  After my form.Form validates the user input values I pass them to a separate (external) process for further processing. This external process can potentially find further errors in the values. Is there a way to inject these errors into the already validated form so they can be displayed via the usual form error display methods? Or, are there better alternative approaches? One suggestions was to include the external processing in the form validation. I'm not crazy about this since the external process does a lot more than just validate.

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• What Java tools/apis to use for decrypting/encrypting

  - by Java_bear

  I am trying to decrypt (and later encrypt) an email message (ebXML). The message contains a Signature element that contains child elements to specify the SignedInfo, SignatureValue and KeyInfo. Also, the message contains an encrypted attachment. Question: What Java tools/apis should be used for decrypting? I would like to find some tool/api that would (automagically) instantiate objects based on whatever is included with the Signature element, so that the data (message) could be easily validated. And the other way around: Creating objects (specifying methods, signature value and keyinfo) and then outputting the xml to go into the message.

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• Input Sanitation Best Practices

  - by Adam Driscoll

  Our team has recently been working on a logic and data layer for our database. We were not approved to utilize Entity or Linq to SQL for the data layer. It was primarily built by hand. A lot of the SQL is auto generated. An obvious down fall of this is the need to sanitize inputs prior to retrieval and insertion. What are the best methods for doing this? Searching for terms like insert, delete, etc seems like a poor way to accomplish this. Is there a better alternative?

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• Protocols/Interfaces in Ruby

  - by fifigyuri

  While coding in Ruby I did not really miss the type-orientedness of Java or C++ so far, but for some cases I think it is useful to have them. For Python there was a project PyProtocols which defined interfaces and protocols for objects. Does a similar initiative also exist for Ruby? I would like to be able to declare the expected parameters for some methods for some objects (for the entire code I find such think useless). It the method during the execution receives an unexpected input, it tries to adapt it or if it cannot, it throws an exception. Does something similar exist for Ruby? Introducing types for a type-less language like Ruby might sound freak, but I think types are sometimes useful. Thanks for help.

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• Acceptable name for extension method that accept null

  - by GaryX

  Hi, I really don't like to call String.IsNullOrEmpty(str). That makes me need to think "String" class first, then call it on the object "str". I like to call str.IsNullOrEmpty(), which doesn't need me to think "String" class. The problem is that extension method accept null instance to call on, which is not the usual case when you call a normal method. My question what do you think will be a convetion name for extension methods that accept null? For string, that is easy, "IsNullOrEmpty()" (anything that contains "IsNull") sounds good for me. For others, like GetDisplayName(), do we name it as "NullOrGetDisplayName" ?

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• What is the definition of a Service object ?

  - by Maskime

  I've been working a lot with PHP. But recently i was sent on a work wich use Java. In PHP i used to do a lot of Singleton object but this pattern has not the same signification in Java that it has in PHP. So i wanted to go for an utility class (a class with static method) but my chief doesn't like this kind of classes and ask me to go for services object. So my guess was that a service object is just a class with a constructor that implement some public methods... Am i right ?

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• Why does the assignment operator return a value and not a reference?

  - by Nick Lowman

  I saw the example below explained on this site and thought both answers would be 20 and not the 10 that is returned. He wrote that both the comma and assignment returns a value, not a reference. I don't quite understand what that means. I understand it in relation to passing variables into functions or methods i.e primitive types are passed in by value and objects by reference but I'm not sure how it applies in this case. I also understand about context and the value of 'this' (after help from stackoverflow) but I thought in both cases I would still be invoking it as a method, foo.bar() which would mean foo is the context but it seems both result in a function call bar(). Why is that and what does it all mean? var x = 10; var foo = { x: 20, bar: function () {return this.x;} }; (foo.bar = foo.bar)();//returns 10 (foo.bar, foo.bar)();//returns 10

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• Simple Sinatra Ajax Not Working

  - by proteantech

  I was trying make an AJAX call from a static file on my computer to a simple sinatra service. The ajax call was returning with an error and no details. The server logged no errors either. Another strange symptom was that the Origin in the request header was null. I turns out that you can't make cross domain ajax calls without a little extra effort. You can set the Access-Control-Allow-Origin header on your sinatra response to expose your service to external domains using a snippet like this: get '/hi' do response['Access-Control-Allow-Origin'] = '*' content_type 'text/plain' "Hello World" end There's also another header you can set to allow other HTTP Methods besides gets, Access-Control-Request-Method. You can find more information by searching around for CORS: Cross Origin Resource Sharing and the previously mentioned headers. Oh, and in case you want to do this in Rails as well you can do something like this in your controller: after_filter :set_access_control_headers def set_access_control_headers headers['Access-Control-Allow-Origin'] = '*' headers['Access-Control-Request-Method'] = '*' end

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• Program output to file in Java (and reading it again)

  - by Cohagen

  I have a large main method in an IO class which creates objects from four different classes in my program (which all use one another to some extent). My main method takes all info in using a scanner, from the console window, and uses this info to call the constructors and methods in the other classes. As this is my first full program in Java I have been focussed on making the main method work via the console, without properly considering file input and output. I cannot see an easy way of making that work now. Ideally what I require is some way of writing everything I input to the console while running the main method to a file, in a format that can be read again and inputed back through the main method? I have refrained from posting the main method as it is 250+ lines long, but will post any relevant parts of it if required. Any help appreciated

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• DomDocument::loadHTML() error during phpunit test execution

  - by ranhan

  I am currently trying to write some unit test against my zend framework controller. When I run the following code I receive this error: public function testListActionShouldContainListTable() { $this->loginToSystem(); $uri = $this->_uriBase . 'campaign/list'; $_SERVER["REQUEST_URI"] = $uri; $this->dispatch('/campaign/list'); $this->assertController('campaign'); $this->assertAction('list'); $this->assertQueryCount('#list',1); } CampaignControllerTests::testListActionShouldContainListTable DOMDocument::loadHTML(): ID alrt already defined in Entity, line: 36 This occurs using any of the assertQuery and assertQueryContains methods. I have searched around but am not really finding a good answer to why it won't allow me to find this html node or how to get around this error. Thanks in advance for any help!

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• sort a list of objects based on runtime property

  - by jijo

  I have an arraylist of VOs. These objects have many properties and corresponding get/set methods. I want to sort this array list based on a property which I'll be getting in runtime. Let me explain in detail. My VO is like this public class Employee { String name; String id; private String getName() { return name; } private String getId() { return id; } } I will be getting a string ‘sort’ in runtime, which can be either ‘id’ of ‘name’. I want to sort the list based on the value of the string. I have tried to use comparator and reflection together, but no luck. I don’t want to use an if loop and create new comparator classes. Any other thoughts?

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• delegating into private parts

  - by FredOverflow

  Sometimes, C++'s notion of privacy just baffles me :-) class Foo { struct Bar; Bar* p; public: Bar* operator->() const { return p; } }; struct Foo::Bar { void baz() { std::cout << "inside baz\n"; } }; int main() { Foo::Bar b; // error: 'struct Foo::Bar' is private within this context Foo f; f->baz(); // fine } Since Foo::Bar is private, I cannot declare b in main. Yet I can call methods from Foo::Bar just fine. Why the hell is this allowed? Was that an accident or by design?

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• How to call method written in C# class library from Silverlight application(xaml.cs file) ?

  - by Shyju

  Can a Silverlight application call a method in a full .NET c# class library? I am trying to add a Silverlight control to my Existing ASP.NET project where i used to add reference to my Business Logic Project and access methods from My UI pages of ASP.NET Web application. Now I have added one Silverlight project to my solution. How can I use the already existing BL method which is in a C# class library ? When tried to add reference, it is saying that "You can only add project reference to other silver light projects in the solution". Should i give up ? Is there any way to get rid of this ?

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• How can I take zooming into account when a user touches a UIScrollView?

  - by Bill

  I have a UIImageView inside of a UIScrollView. The parent scroll view allows zooming and panning. When the user taps a point in the scroll view, I want to find the location in the raw image inside the UIImageView - i.e. I want the point after including any zooming and panning the user has done in the scroll view. Right now, I have a UIScrollView subclass called ForwardingScrollView that handles touch events and attempts to convert them into locations in the coordinate system of the child image view. I tried adding contentOffset to these points, tried multiplying them by zoomScale, and even tried doing both. I also tried calling [touch locationInView: self] and [touch locationInView: parent], but none of these methods correctly return the point that I clicked in the underlying image. What's the best way to do this? Thanks in advance.

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• What is a 'best practice' backup plan for a website?

  - by HollerTrain

  I have a website which is very large and has a large user-base. I am trying to think of a 'best practice' way to create a back up or mirror website, so if something happens on domain.com, I can quickly point the site to backup.domain.com via 401 redirect. This would give me time to troubleshoot domain.com while everyone is viewing backup.domain.com and not knowing the difference. Is my method the ideal method, or have you enacted better methods to creating a backup site? I don't want to have the site go down and then get yelled at every minute while I'm trying to fix it. Ideally I would just 'flip the switch' and it would redirect the user to a backup. Any insight would be greatly appreciated.

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