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• Will unused deconstructors be optimized out?

  - by Brendan Long

  Assuming MyClass uses the default deconstructor (or no deconstructor), and this code: MyClass buffer[] = new MyClass[i]; // Construct N objects using placement new for(size_t i = 0; i < N; i++){ ~buffer[i]; } delete[] buffer; Is there any optimizer that would be able to remove this loop? Also, is there any way for my code to detect if MyClass is using an empty/default constructor?

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• undefined reference to static member variable

  - by Max

  Hi. I have this class that has a static member. it is also a base class for several other classes in my program. Here's its header file: #ifndef YARL_OBJECT_HPP #define YARL_OBJECT_HPP namespace yarlObject { class YarlObject { // Member Variables private: static int nextID; // keeps track of the next ID number to be used int ID; // the identifier for a specific object // Member Functions public: YarlObject(): ID(++nextID) {} virtual ~YarlObject() {} int getID() const {return ID;} }; } #endif and here's its implementation file. #include "YarlObject.hpp" namespace yarlObject { int YarlObject::nextID = 0; } I'm using g++, and it returns three undefined reference to 'yarlObject::YarlObject::nextID linker errors. If I change the ++nextID phrase in the constructor to just nextID, then I only get one error, and if I change it to 1, then it links correctly. I imagine it's something simple, but what's going on?

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• How to Iterate a Resharper Template ?.

  - by sree

  I have a small Resharper Template I have written for Null check of a function Parameter (C#). Check.IsNotNull($param$, "$param$"); - Suggest Parameter - #1 I can now null check the function paramters one by one. But I want to be able to null check all the paramters at once through a template. Is it Possible in Resharper?. Is there someting like a "$Foreach" using which I can loop through parameter variables and write the code to check them one by one ?. (without writing out the foreach into the code) I see that the "Alt + Ins" does something similar. (Taking all Properties on the class and making them as parameters of a constructor). So hoping that there's a way out.

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• How to synchronize static method in java.

  - by Summer_More_More_Tea

  Hi there: I come up with this question when implementing singleton pattern in Java. Even though the example listed blow is not my real code, yet very similar to the original one. public class ConnectionFactory{ private static ConnectionFactory instance; public static synchronized ConnectionFactory getInstance(){ if( instance == null ){ instance = new ConnectionFactory(); } return instance; } private ConnectionFactory(){ // private constructor implementation } } Because I'm not quite sure about the behavior of a static synchronized method, I get some suggestion from google -- do not have (or as less as possible) multiple static synchronized methods in the same class. I guess when implementing static synchronized method, a lock belongs to Class object is used so that multiple static synchronized methods may degrade performance of the system. Am I right? or JVM use other mechanism to implement static synchronized method? What's the best practice if I have to implement multiple static synchronized methods in a class? Thank you all! Kind regards!

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• Design pattern to encapsulate common funtionality among UI controls

  - by Dan

  I'm brainstorming some ideas around a pattern to use for the following scenario. I have some 3rd party controls that I want to add common functionality to. Functionality is added by handling several of the the events and doing certain things when the events fire along with adding some private variables to hold some state info between events. I want to reuse the code and functionality so this is what I'd typically do. Create a class for this functionality and pass in the instance of the control that I want to add the functionality to in the constructor. Then I can add event handlers to the control in the instance of the class. Can anyone think of alternative patterns to use in order to create this kind of reusable functionality.

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• test cases for testing a strtok-alike function [C++]

  - by Neeraj

  Consider the following class definition: class StrToTokens { StrToTokens(const char* str, const char* delimiters = "\t\r\n"); //constructor string getNextToken(); void reset(); bool empty(); } Can someone list some good testcases to test the above class. A few I could think of are: empty string, empty delimiters, repeated delimiters, consecutive delimiters, string with only delimiters. However, the interviewer expected some more(better ones). Can you help out. Thanks.

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• Performance problem loading lots of user controls

  - by codymanix

  My application is loading a bunch of the same user control into a ScrollPanel. The problem is, this is very slow. The profiler show that the method Application.LoadComponent(), which is called internally by in the designer code in the constructor of my user control, is the bottleneck. The documentation of this method says, that this method load XAML files. I alway though the compiler compiles XAML to BAML and embedds it into the assembly. So the question is, how can I use BAML instead of XAML? Is there another way to make loading my user controls faster?

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• Parameter attributes in c#

  - by ng

  How can I do the following with c# attributes. Below is a snippet of Java that annotates parameters in a constructor. public class Factory { private final String name; private final String value; public Factory(@Inject("name") String name, @Inject("value") String value) { this.name = name; this.value = value; } } From looking at c# annotations it does not look like I can annotate parameters. Is this possible?

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• how does serializable work in java?

  - by Karl Trumstedt

  If I have an instance of a class that I store in a session I need to make it serializable. This class has a static variable, will this be serialized in every instance stored? The static variable is a reference to a cache containing a lot of data in the background. Will all of this data be serialized? If so, it seems preferable to make this variable transient and re-fetch the cache instance each time the instance is restored. Maybe not store the cache instance at all in the class. Will the constructor execute when a class is restored from a serialized state? if not is there any other method I can use to re-instate a transient variable?

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• Method params match signature, but still getting error

  - by Jason

  I am in the midst of converting a VB library to C#. One of my methods has the following signature in VB: Private Shared Sub FillOrder(ByVal row As DataRowView, ByRef o As Order) In C# I converted it to: private static void FillOrder(DataRowView row, ref Order o) From my constructor inside my Order class, I am calling the FillOrder() method like so: DataView dv = //[get the data] if (dv.Count > 0) { FillOrder(dv[0], this); } In VB, this works: Dim dv As DataView = '[get data]' If dv.Count > 0 Then FillOrder(dv.Item(0), Me) End If However, in VS10 in the C# file I am getting a red squiggle under this call with the following error: The best overloaded method match for [the method] has some invalid arguments This was working code in VB. What am I doing wrong?

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• Injecting a dependancy into a base class

  - by Jamie Dixon

  Hey everyone, I'm on a roll today with questions. I'm starting out with Dependency Injection and am having some trouble injecting a dependency into a base class. I have a BaseController controller which my other controllers inherit from. Inside of this base controller I do a number of checks such as determining if the user has the right privileges to view the current page, checking for the existence of some session variables etc. I have a dependency inside of this base controller that I'd like to inject using Ninject however when I set this up as I would for my other dependencies I'm told by the compiler that: Error 1 'MyProject.Controllers.BaseController' does not contain a constructor that takes 0 argument This makes sense but I'm just not sure how to inject this dependency. Should I be using this pattern of using a base controller at all or should I be doing this in a more efficient/correct way?

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• Create a class with array of objects.

  - by Bi

  Hi Code below defines a ChargeCustomer class that contains an array of type "customers". I want to be able to create an object with either 1 "customer" or 2 "customers" based on the constructor parameters. Is this the right way to do so in C#: public class ChargeCustomer { private Customer[] customers; public ChargeCustomer( string aName, string bName, int charge ) { customers = new Customer[2]; customers[0] = new Customer(aName, charge); customers[1] = new DropBox(bName, charge); } public ChargeCustomer( string bName, int charge ) { customers = new Customer[1]; customers[0] = new Customer( bName, charge ); } } Thanks!

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• Want to understand C++ sentry object

  - by Romain Hippeau

  I answered this [question][1] and somebody else had answered as he 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 ? [1]: http://stackoverflow.com/questions/2688043/call-return-feature-of-classic-cc-with-classes-what-modern-languages-have-it/2688095#2688095 /

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• How to initialise an array inside a struct without doing each element separately? (C++)

  - by Janet

  My questions are in the code, but basically i want to know how/if I can do the two commented out lines? I know I can do it in a constructor but I don't want to! struct foo { int b[4]; } boo; //boo.b[] = {7, 6, 5, 4}; // <- why doesn't this work? (syntax error : ']') //boo.b = {7, 6, 5, 4}; // <- or else this? (syntax error : '{') boo.b[0] = 7; // <- doing it this way is annoying boo.b[1] = 6; // : boo.b[2] = 5; // : boo.b[3] = 4; // <- doing it this way is annoying boo.b[4] = 3; // <- why does this work! (Using: C++, Visual Studio 2005.)

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• How to add a custom loglevel to Python's logging facility

  - by tuergeist

  Hi, I'd like to have loglevel TRACE (5) for my application as I don't think that debug() is enought. Additionally log(5, msg) isn't what I want. The question is, how can I add a custom log level to a Python logger? Actually I've a mylogger.py with the following content: import logging @property def log(obj): myLogger = logging.getLogger(obj.__class__.__name__) return myLogger In my code I use it in the following way: class ExampleClass(object): from mylogger import log def __init__(self): '''The constructor with the logger''' self.log.debug("Init runs") Now I'd like to call self.log.trace("foo bar") Thanks in advance for your help.

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• Pattern matching for lambda expressions

  - by alphomega

  21 --Primitive recursion constructor 22 pr :: ([Int] -> Int) -> ([Int] -> Int) -> ([Int] -> Int) 23 pr f g = \xs 0 -> f xs 24 pr f g = \xs (y+1) -> g xs y ((pr f g) xs y) I want the function this function creates to act differently on different inputs, so that it can create a recursive function. As expected, the above code doesn't work. How do I do something like pattern matching, but for the function it creates? Thanks

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• How to default-initialize local variables of built-in types in C++?

  - by sharptooth

  How do I default-initialize a local variable of primitive type in C++? For example if a have a typedef: typedef unsigned char boolean;//that's Microsoft RPC runtime typedef I'd like to change the following line: boolean variable = 0; //initialize to some value to ensure reproduceable behavior retrieveValue( &variable ); // do actual job into something that would automagically default-initialize the variable - I don't need to assign a specific value to it, but instead I only need it to be intialized to the same value each time the program runs - the same stuff as with a constructor initializer list where I can have: struct Struct { int Value; Struct() : Value() {} }; and the Struct::Value will be default-initialized to the same value every time an instance is cinstructed, but I never write the actual value in the code. How can I get the same behavior for local variables?

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• Java - Thread safety of ArrayList constructors

  - by andy boot

  I am looking at this piece of code. This constructor delegates to the native method "System.arraycopy" Is it Thread safe? And by that I mean can it ever throw a ConcurrentModificationException? public Collection<Object> getConnections(Collection<Object> someCollection) { return new ArrayList<Object>(someCollection); } Does it make any difference if the collection being copied is ThreadSafe eg a CopyOnWriteArrayList? public Collection<Object> getConnections(CopyOnWriteArrayList<Object> someCollection) { return new ArrayList<Object>(someCollection); }

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• Can I add and remove elements of enumeration at runtime in Java

  - by Brabster

  It is possible to add and remove elements from an enum in Java at runtime? For example, could I read in the labels and constructor arguments of an enum from a file? @saua, it's just a question of whether it can be done out of interest really. I was hoping there'd be some neat way of altering the running bytecode, maybe using BCEL or something. I've also followed up with this question because I realised I wasn't totally sure when an enum should be used. I'm pretty convinced that the right answer would be to use a collection that ensured uniqueness instead of an enum if I want to be able to alter the contents safely at runtime.

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• Why baseclass calls method of subclass?

  - by twlkyao

  I encounter some code like the following: BaseClass: public class BaseClass { String name = "Base"; public BaseClass() { printName(); } public void printName() { System.out.println(name + "——Base"); } } DrivedClass: public class SubClass extends BaseClass { String name = "Sub"; public SubClass() { printName(); } public void printName() { System.out.println(name + "——Sub"); } public static void main(String[] args) { new SubClass(); } } When run the code, the output is: null——Sub Sub——Sub while it should be: Base——Base Sub——Sub I wonder why the BaseClass constructor calls the SubClass method, can anybody explain this? Thanks in advance.

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• how to get TabHeader on trigger

  - by CurlyFro

  i have a tabcontrol. i'm trying to pass the tabcontrol as a parameter to figure out the selected tab item so i can get the tab header name. Binding this doesn't seem to work. ideas? <TabControl Background="#FFF9F9F9" Height="650"> <i:Interaction.Triggers> <i:EventTrigger EventName="SelectionChanged"> <n:ExecuteCommandAction Command="{Binding UpdateTabCommand}" Parameter="{Binding this}"/> </i:EventTrigger> </i:Interaction.Triggers> in my viewmodel constructor i have: _updateTabCommand = new ActionCommand< TabControl>(UpdateTab); private method: public void UpdateTab(TabControl tabControl) { var tabItem = (TabItem)tabControl.SelectedItem;

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• Copying a 2D non-space array to another

  - by Jay

  I'm a total programming newb who started learning java programming this sem at uni. I'm up to a step where i need to copy some elements from one method to another. This program i'm creating is called an L_Game. The question I'm stuck is: the project(Slide other) method should take another slide as a parameter, and copy each non-space cell from this slide into the other slide (i.e. like a projector projecting slides onto a screen. I previously made a constructor with the parameter cells in it and believe i copied it to the project(Slide other) method. But i'm not sure what to do to copy each "non-space cell" With the "for" method or the "if" method? If my question isn't typed correctly or have information missing, please let me know. Any help will be appreciated. (I obviously have no idea with what i'm doing...)

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• silverlight adding single prism command delegate to a list of items in xaml

  - by bobwah

  I'm building a menu using Prism (using a trtelerik tree view with hierarchy data templates but hopefully the details don't matter) and I'm trying to set up a Click.Command on each menu items bindings that will all call the same delegate command which is defined in the view model. The menu is built up out of items which I don't really want to put any references to the command in. How do I bind the command to each of these items in xaml? I've looked around and it looks like in WPF I could use a relative source binding and find ancestors but there doesn't seem to be a way of doing this in silverlight. Can I setup the delegate as a static resource somehow? I don't think I can create a static resource to the view model as this uses Unity to resolve paramters to it's constructor.

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• Mask image does not appear on the screen

  - by Ponty

  I have imported to the library two images and have given them the custom class names MaskImage and MaskedImage. Then i write the code: package { import flash.display.*; public class MaskDemo extends Sprite { // Properties private var sprMaskedImage:Sprite; private var sprMaskImage:Sprite; private var bmMaskedImage:Bitmap; private var bmMaskImage:Bitmap; // Constructor public function MaskDemo() { do_magic(); } // Methods private function do_magic():void { bmMaskedImage = new Bitmap(new MaskedImage(0, 0)); bmMaskImage = new Bitmap(new MaskImage(0, 0)); sprMaskedImage = new Sprite(); sprMaskedImage.addChild(bmMaskedImage); sprMaskImage = new Sprite(); sprMaskImage.addChild(bmMaskImage); sprMaskedImage.mask = sprMaskImage; this.addChild(sprMaskImage); } } } But it does not appear anything on the display. Any ideas why is happening that?

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• Inheritance - initialization problem

  - by dumbquestion

  I have a c++ class derived from a base class in a framework. The derived class doesn't have any data members because I need it to be freely convertible into a base class and back - the framework is responsible for loading and saving the objects and I can't change it. My derived class just has functions for accessing the data. But there are a couple of places where I need to store some temporary local variables to speed up access to data in the base class. mydata* MyClass::getData() { if ( !m_mydata ) { // set to NULL in the constructor m_mydata = some_long_and complex_operation_to_get_the_data_in_the_base() } return m_mydata; } The problem is if I just access the object by casting the base class pointer returned from the framework to MyClass* the ctor for MyClass is never called and m_mydata is junk. Is there a way of only initializing the m_mydata pointer once?

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