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• Java: Best practices for turning foreign horror-code into clean API...?

  - by java.is.for.desktop

  Hello, everyone! I have a project (related to graph algorithms). It is written by someone else. The code is horrible: public fields, no getters/setters huge methods, all public some classes have over 20 fields some classes have over 5 constructors (which are also huge) some of those constructors just left many fields null (so I can't make some fields final, because then every second constructor signals errors) methods and classes rely on each other in both directions I have to rewrite this into a clean and understandable API. Problem is: I myself don't understand anything in this code. Please give me hints on analyzing and understanding such code. I was thinking, perhaps, there are tools which perform static code analysis and give me call graphs and things like this.

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• What is "sentry object" in C++?

  - by Romain Hippeau

  I answered this question, and Potatoswatter answered too as The modern C++ equivalent would be a sentry object: construct it at the beginning of a function, with its constructor implementing call(), and upon return (or abnormal exit), its destructor implements I am not familiar with using sentry objects in C++. I thought they were limited to input and output streams. Could somebody explain to me about C++ sentry objects as well as how to use them as an around interceptor for one or more methods in a class ? i.e. How to do this ? Sentry objects are very similar indeed. On the one hand they require explicit instantiation (and being passed this) but on the other hand you can add to them so that they check not only the invariants of the class but some pre/post conditions for the function at hand.

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• Can I pass a child class to a reference of a parent class?

  - by michael

  Hi, I have a class A which takes a reference of B in its constructor. class A { public: A(B& b); } And I have a class SubB which is a child class of B: class SubB : public B { //omitted... } In my code, I create a SubB and pass it to A: SubB subB; A a(subB); But I get this compile Error: error: ‘B’ is an inaccessible base of ‘SubB’ Can I pass a reference of SubB as B? Thank you.

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• In Prism (CAL), how can I RegisterPresenterWithRegion instead of RegisterViewWithRegion

  - by Edward Tanguay

  I have a module in a Prism application and in its initialize method I want to register a presenter instead of a view with a region, i.e. I want to do this: PSEUDO-CODE: regionManager.RegisterPresenterWithRegion( "MainRegion", typeof(Presenters.EditCustomerPresenter)); instead of loading a view like this: regionManager.RegisterViewWithRegion( "MainRegion", typeof(Views.EditCustomerView)); The presenter would of course bring along its own view and ultimately register this view in the region, but it would allow me to bind the presenter to the view in the presenter's constructor instead of binding the two together in XAML (which is more of a decoupled MVVM pattern which I want to avoid here). How can I add a Presenter to a Region instead of a view? namespace Client.Modules.CustomerModule { [Module(ModuleName = "CustomerModule")] public class CustomerModule : IModule { private readonly IRegionManager regionManager; public CustomerModule(IRegionManager regionManager) { this.regionManager = regionManager; } public void Initialize() { regionManager.RegisterViewWithRegion("MainRegion", typeof(Views.EditCustomerView)); } } }

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• Static classes in PHP via abstract keyword?

  - by Boldewyn

  According to the PHP manual, a class like this: abstract class Example {} cannot be instantiated. If I need a class without instance, e.g. for a registry pattern: class Registry {} // and later: echo Registry::$someValue; would it be considered good style to simply declare the class as abstract? If not, what are the advantages of hiding the constructor as protected method compared to an abstract class? Rationale for asking: As far as I see it, it could a bit of feature abuse, since the manual refers to abstract classes more as like blueprints for later classes with instantiation possibility.

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• C#: How to inherit constructors?

  - by Ian Boyd

  Imagine a base class with many constructors and a virtual method public class Foo { ... public Foo() {...} public Foo(int i) {...} ... public virtual void SomethingElse() {...} ... } and now I want to create a descendant class that overrides the virtual method: public class Bar : Foo { public override void SomethingElse() {...} } And another descendant that does some more stuff: public class Bah : Bar { public void DoMoreStuff() {...} } Do I really have to copy all constructors from Foo into Bar and Bah? And then if I change a constructor signature in Foo, do I have to update it in Bar and Bah? Is there no way to inherit constructors? Is there no way to encourage code reuse?

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• C# property definition

  - by Sunny

  For C# properties, I can do this: public class Employee{ public string Name { get; private set; } public Employee(string name){ Name = name; } } which means that the Name property can be set within the class Employee & can be read publicly. But, if I want to restrict the set to only within the constructors of the Employee class, I need to do: public class Employee{ public readonly string Name = String.Empty; public Employee(string name){ Name = name; } } But, for this case, I had to change the property to a field. Is there any reason this is not possible/allowed in C#: public class Employee{ public string Name { get; private readonly set; } public Employee(string name){ Name = name; } } IMO this will allow us to have properties which can be set only in the constructor & does not require us to change properties to fields... Thanks!

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• QT drawing without erasing widget

  - by faya

  Hello, If I have a derived object of QWidget class and on slot function in it I have an update(). here is some pseudocode: *.h slot: updateNow(); *.cpp constructor() { setPalllete(QPallete(QColor(250,250,200))); setAUtoFillBackground(true); } updateNow() { update(); } paintEvent() { QPainter painter(this); painter.drawRect(1,2,3,4); } So how should I don't get erased my pallete after update() call? P.S. - Sorry for my English and only pseudocode.

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• Ruby on Rails: building a model with an attribute not in the database?

  - by randombits

  I have a model that sets one of its attributes based off of a form parameter that a user submits. The model is a child resource to a parent resource Home. A hypothetical example is the following: A class Person has an age attribute. The user submits a birthdate as an HTTP POST parameter and from that, I need to derive the age of the user. So I'd do something like this: @home.people.build(:name => params[:name], :birthdate => params[:birthdate]) Rails would barf on that for obvious reasons, complaining it doesn't know what the attribute birthdate is. What's the proper way of going about this? Is it possible to use the build constructor with the supplied solution so that my foreign key relations are also setup properly? If not, what's a better way to work around this problem?

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• How do I convert a windows forms app from C# to VB ?

  - by SLC

  I've been converting all kinds of other things, classes, interfaces, ASP.NET MVC apps, and WPF applications, but I am stumped as to how to convert a windows forms application, as the whole structure seems to be different. Does anyone have any advice on how to tackle this problem? I see essentially that you have two files, Form1.cs and Form1.Designer.cs. Literally translating them from C# to VB doesn't work because of some intricacies or other of how Visual Basic works. I think you /might/ be able to convert Form1.cs in this way, as it's just a constructor plus event handlers, but the designer contains the references to the controls etc. and I am not sure how to go about doing that. I am using Visual Studio 2010 Beta 2.

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• flex: is there a way to dispach a custom event from one loaded flex application to the other ?

  - by ufk

  Hello. I have an HTML page that loads two different SWF files. is there a way to dispatch a custom event from one flex application to another ? to create a custom event I extend the Event class and I add another variable to the constructor called params which is an Object. I use EventDispatcher to dispatch the events. I have no idea how to do that between one flex application to the other. is it even possible ? If it's not, is there any other way that these two flex applications can communicate without opening a LocalConnection ? Using flex 4.5 thanks!

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• Creating New Objects in JavaScript

  - by Ken Ray

  I'm a relatively newbie to object oriented programming in JavaScript, and I'm unsure of the "best" way to define and use objects in JavaScript. I've seen the "canonical" way to define objects and instantiate a new instance, as shown below. function myObjectType(property1, propterty2) { this.property1 = property1, this.property2 = property2 } // now create a new instance var myNewvariable = new myObjectType('value for property1', 'value for property2'); But I've seen other ways to create new instances of objects in this manner: var anotherVariable = new someObjectType({ property1: "Some value for this named property", property2: "This is the value for property 2" }); I like how that second way appears - the code is self documenting. But my questions are: Which way is "better"? Can I use that second way to instantiate a variable of an object type that has been defined using the "classical"way of defining the object type with that implicit constructor? If I want to create an array of these objects, are there any other considerations? Thanks in advance.

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• CodeIgniter's Scaffolding not working

  - by 01010011

  Hi, I keep getting a 404 Page Not Found whenever I try to access CodeIgniter's Scaffolding page in my browser, like so: localhost/codeignitor/index.php/blog/scaffolding/mysecretword I can access localhost/codeignitor/index.php/blog just fine. I followed CodeIgnitor's instructions in their "Create a blog in 20 minutes" by storing my database settings in the database.php file; and automatically connecting to the database by inserting "database" in the core array of the autoload.php; and I've added both parent::Controller(); and $this-load-scaffolding('myTableName') to blog's constructor. It still gives me this 404. Any suggestions?

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• Copying a Polymorphic object in C++

  - by doron

  I have base-class Base from which is derived Derived1, Derived2 and Derived3. I have constructed an instance for one of the the derived classes which I store as Base* a. I now need to make a deep copy of the object which I will store as Base* b. As far as I know, the normal way of copying a class is to use copy constructors and to overload operator=. However since I don't know whether a is of type Derived1, Derived2 or Derived3, I cannot think of a way of using either the copy constructor or operator=. The only way I can think of to cleanly make this work is to implement something like: class Base { public: virtual Base* Clone() = 0; }; and the implement Clone in in the derived class as in: class Derivedn : public Base { public: Base* Clone() { Derived1* ret = new Derived1; copy all the data members } }; Java tends to use Clone quite a bit is there more of a C++ way of doing this?

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• How to return radio checked object with jQuery ?

  - by Kim

  HTML <input type="radio" name="rdName" id="uniqueID1" value="1" checked="checked"> <input type="radio" name="rdName" id="uniqueID2" value="2"> <input type="radio" name="rdName" id="uniqueID3" value="3"> jQuery #1 $('input:radio[name=rdName]:checked').val(); jQuery #2 $('input[name=rdName]:checked'); jQuery #1 gets the value of checked radio, but I need to get the whole object to get the ID. jQuery #2 get this (from Chrome Dev console). Object "0" is the actual object I need, but I am unable to just that. 0: HTMLInputElement constructor: function Object() context: HTMLDocument length: 1 prevObject: Object selector: input[name=rdName]:checked __proto__: Object Any ideas how to isolate the needed object ?

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• Java Spring 3.0 MVC Annotation vs COC. Whats the preferred method in the Java community?

  - by Athens

  I am using Spring's MVC framework for an application I'm hosting on Google's App Engine. So far, my controllers are registered via the @Controller annotation; however, prior to getting into Spring, I evaluated ASP.net MVC 2 which requires no configuration and is based on convention. Is convention over configuration (COC) the current and preferred method in the Java community to implement MVC with Spring. Also, this may be a result of my limited knowledge so far but i noticed that i could only instantiate my Controllers the required constuctor injection if i use the COC method via the ControllerClassNameHandlerMapping. For instance the following controller bean config will fail if i use the defaultannotationhandlermapping. <bean id="c" class="com.domain.TestController"> <constructor-arg ref="service" /> </bean> <bean id="service" class="com.domain.Service" /> My com.domain.TestController controller works fine if i use ControllerClassNameHandlerMapping/COC but it results in an error when i use defaultannotationhandlermapping/Annotations.

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• Java: constructing a file from a URI?

  - by AP257

  I need to obtain a File object from a URI, working in Java, but keep getting a length of zero - though I know the file size is not zero. I need the File object to pass to another constructor. I'm not sure if it's because I'm constructing it in the wrong way? Here's my code: File videoFile = new File(videoURI.getPath()); if (videoFile == null) { Log.d(LOG_TAG, "File not found!"); return false; } Log.d(LOG_TAG, "about to upload, filepath: " + videoFile.getPath()); Log.d(LOG_TAG, "File length: " + String.valueOf(videoFile.length())); The log output doesn't spit out 'File not found!', and prints a non-null path, but shows a length of 0.

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• c++ defining a static member of a template class with type inner class pointer

  - by Jack

  I have a template class like here (in a header) with a inner class and a static member of type pointer to inner class template <class t> class outer { class inner { int a; }; static inner *m; }; template <class t> outer <t>::inner *outer <t>::m; when i want to define that static member i says "error: expected constructor, destructor, or type conversion before '*' token" on the last line (mingw32-g++ 3.4.5)

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• Beginner having a problem with classes

  - by David

  I'm working through O'Reilly's "Learning Python" and having a problem with classes. I think I understand the concept, but in practice have stumbled upon this problem. Fron page 88-89: >>> class Worker: def __innit__(self, name, pay): self.name=name self.pay=pay def lastName(self): return self.name.split()[-1] def giveRaise(self, percent): self.pay*=(1.0+percent) Then the book says "Calling the class like a function generates instances of a new type ...etc" and gives this example. bob = Worker('Bob Smith', 50000) This gives me this error: TypeError: this constructor takes no arguments. And then I start muttering profanities. So what am I doing wrong here? Thanks for the help.

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• Should i use HttpResponse.End() for a fast webapp?

  - by acidzombie24

  HttpResponse.End() seems to throw an exception according to msdn. Right now i have the choice of returning a value to say end thread (it only goes 2 functions deep) or i can call end(). I know that throwing exceptions is significantly slower (read the comment for a C#/.NET test) so if i want a fast webapp should i consider not calling it when it is trivially easy to not call it? -edit- I do have a function call in certain functions and in the constructor in classes to ensure the user is logged in. So i call HttpResponse.End() in enough places although hopefully in regular site usage it doesn't occur too often.

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• PHP & MySQLi timeout

  - by Dt7

  Whenever I try to create a mysqli object, as in; $mysqli = new mysqli(host, user, pass, table); ...the page just loads for around a minute, then stops, showing all the content of the page up until that line. info() says that MySQLi (and MySQL if that matters) are enabled, and I can access the MySQL CLI. I'm also working on a local machine, not a remote server. I feel like I've missed something obvious. Can anyone shed some light on it? Edit: just for clarification, I am actually putting real values into the mysqli constructor :)

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• Java - SwingWorker - problem in done() method

  - by Yatendra Goel

  I am using javax.swing.SwingWorker for the first time. I want to update a JLabel from the interim result published by the swing worker as follows: publish("Published String"); Now to update the JLabel, I have coded the following: process(List<String> chunks) { if (chunks.size() > 0) { String text = chunks.get(chunks.size() - 1); label.setText(text); } } The above code works but my problem(or to be more specific, my doubt) is as follows: The above swing worker task is an annonymous inner class so it can access label field. But what if I want to make the swing worker class a non-inner class. Should I need to pass label as an argument to the constructor of swing worker class so that the process() method can access. Or Is there any other way? What approach does other developer follow to update UI components from the swing worker class' result when the swing worker class is not an inner class?

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• Is the JavaScript RegExp implicit method deprecated?

  - by Eric

  So everyone knows what I mean by "implicit methods"? They're like those default properties from the Windows COM days of yore, where you could type something like val = obj(arguments) and it would be interpreted as val = obj.defaultMethod(arguments) I just found out JavaScript has the same thing: the default method of a RegExp object appears to be 'exec', as in /(\w{4})/('yip jump man')[1] ==> jump This even works when the RegExp object is assigned to a variable, and even when it's created with the RegExp constructor, instead of /.../, which is good news to us fans of referential transparency. Where is this documented, and/or is it deprecated?

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• C++ Class Static variable problem - C programmer new to C++

  - by Microkernel

  Hi guys, I am a C programmer, but had learnt C++ @school longtime back. Now I am trying to write code in C++ but getting compiler error. Please check and tell me whats wrong with my code. typedef class _filter_session { private: static int session_count; /* Number of sessions count -- Static */ public: _filter_session(); /* Constructor */ ~_filter_session(); /* Destructor */ }FILTER_SESSION; _filter_session::_filter_session(void) { (this->session_count)++; return; } _filter_session::~_filter_session(void) { (this->session_count)--; return; } The error that I am getting is "error LNK2001: unresolved external symbol "private: static int _filter_session::session_count" (?session_count@_filter_session@@0HA)" I am using Visual Studio 2005 by the way. Plz plz help me. Regards, Microkernel

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• Using static mutex in a class

  - by Dmitry Yudakov

  I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe. I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members. class MyClass { static boost::mutex mx; // 3rd party library members public: MyClass(); ~MyClass(); }; MyClass::MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // create and init 3rd party library stuff } MyClass::~MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // destroy 3rd party library stuff } I cannot link because I receive error: undefined reference to `MyClass::mx` Do I need some special initialization of such static member? Is the whole conception of static mutex wrong?

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