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  • Auto pointer for unsigned char array?

    - by Gianluca
    I'd need a class like std::auto_ptr for an array of unsigned char*, allocated with new[]. But auto_ptr only calls delete and not delete[], so i can't use it. I also need to have a function which creates and returns the array. I came out with my own implementation within a class ArrayDeleter, which i use like in this example: #include <Utils/ArrayDeleter.hxx> typedef Utils::ArrayDeleter<unsigned char> Bytes; void f() { // Create array with new unsigned char* xBytes = new unsigned char[10]; // pass array to constructor of ArrayDeleter and // wrap it into auto_ptr return std::auto_ptr<Bytes>(new Bytes(xBytes)); } ... // usage of return value { auto_ptr<Bytes> xBytes(f()); }// unsigned char* is destroyed with delete[] in destructor of ArrayDeleter Is there a more elegant way to solve this? (Even using another "popular" library)

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  • How often do you implement the big three?

    - by Neil Butterworth
    I was just musing about the number of questions here that either are about the "big three" (copy constructor, assignment operator and destructor) or about problems caused by them not being implemented correctly, when it occurred to me that I could not remember the last time I had implemented them myself. A swift grep on my two most active projects indicate that I implement all three in only one class out of about 150. That's not to say I don't implement/declare one or more of them - obviously base classes need a virtual destructor, and a large number of my classes forbid copying using the private copy ctor & assignment op idiom. But fully implemented, there is this single lonely class, which does some reference counting. So I was wondering am I unusual in this? How often do you implement all three of these functions? Is there any pattern to the classes where you do implement them?

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  • Dynamically Loading a DLL

    - by TooFat
    I am trying to simply load a dll written in C# at run time and create an instance of a class in that dll. Assembly a = Assembly.LoadFrom(@"C:\Development\DaDll.dll"); Type type = a.GetType("FileReleaseHandler", true); TestInterface.INeeedHelp handler = Activator.CreateInstance(type) as TestInterface.INeeedHelp; No errors are thrown, and if I step through the code I can walk though the FileReleaseHandler Class as it executes the constructor but the value of handler is always null. What am I missing here? or even is there a better way I should be going about this?

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  • WPF Binding not updating when binded object is updated

    - by Chris Klepeis
    I'm trying to bind to a custom control like so: <my:GanttChartTaskListView Name="ganttChartTaskListView1" ItemsSource="{Binding Source={x:Static local:TaskCollection.taskList}}" /> In my WPF Window constructor I add add an item to my taskList, when it loads I can see that item in my custom control, however, when I subsequently add items it does not update. I tried setting Mode=TwoWay, however, then it says the "Path" is required and I'm not familiar with binding like that (this is new to me). Here is my TaskCollection class: namespace ProjectManager { public static class TaskCollection { private static List<TaskItem> _taskList = new List<TaskItem>(); public static List<TaskItem> taskList { get {return _taskList; } set { _taskList = value; } } } } Any ideas? Is there a better / easier way to do this?

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  • Pass Session data to a Class Library without using a bunch of constructors?

    - by sah302
    Hi all, I've got my application here where literally every object has a lastUpdatedBy property. The information I put into here is the person's username, which is retrieved from the session("username") variable. How can I pass this data to my DAL in the class library? At first I was just passing in the value into each method, but this is ridiculous I thought, there should be no reason to do that every time a method is called. Then I thought well if I just put it in a constructor for each of the DAL related classes, that will make it even easier. However, even still on any given page, I've got a plethora of New() declarations, for which every single line I need to pass in the session username casted as a string. Is there an even still more efficient way of doing this so that I could only declare this in one place, and everything will know what it is and I can pass it to classes in a class library?

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  • Which isolation level should I use for the following insert-if-not-present transaction?

    - by Steve Guidi
    I've written a linq-to-sql program that essentially performs an ETL task, and I've noticed many places where parallelization will improve its performance. However, I'm concerned about preventing uniquness constraint violations when two threads perform the following task (psuedo code). Record CreateRecord(string recordText) { using (MyDataContext database = GetDatabase()) { Record existingRecord = database.MyTable.FirstOrDefault(record.KeyPredicate()); if(existingRecord == null) { existingRecord = CreateRecord(recordText); database.MyTable.InsertOnSubmit(existingRecord); } database.SubmitChanges(); return existingRecord; } } In general, this code executes a SELECT statement to test for record existance, followed by an INSERT statement if the record doesn't exist. It is encapsulated by an implicit transaction. When two threads run this code for the same instance of recordText, I want to prevent them from simultaneously determining that the record doesn't exist, thereby both attempting to create the same record. An isolation level and explicit transaction will work well, except I'm not certain which isolation level I should use -- Serializable should work, but seems too strict. Is there a better choice?

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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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  • 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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  • Is it a bug???????????????/

    - by Knowing me knowing you
    I'm using VS2010 Ultimate. Having code: //file IntSet.h #include "stdafx.h" #pragma once /*Class representing set of integers*/ template<class T> class IntSet { private: T** myData_; std::size_t mySize_; std::size_t myIndex_; public: #pragma region ctor/dtor explicit IntSet(); virtual ~IntSet(); #pragma endregion #pragma region publicInterface IntSet makeUnion(const IntSet&)const; IntSet makeIntersection(const IntSet&)const; IntSet makeSymmetricDifference(const IntSet&)const; void insert(const T&); #pragma endregion }; //file IntSet_impl.h #include "StdAfx.h" #include "IntSet.h" #pragma region ctor/dtor template<class T> IntSet<T>::IntSet():myData_(nullptr), mySize_(0), myIndex_(0) { } template<class T> IntSet<T>::~IntSet() { } #pragma endregion #pragma region publicInterface template<class T> void IntSet<T>::insert(const T& obj) {/*IF I SET A BREAKPOINT HERE AND AFTER THAT I CHANGE SOMETHING IN THE BODY I'M GETTING MSG SAYING THAT THE BREAKPOINT WILL NOT CURRENTLY BE HIT, AFTER I REBUILD THE BREAKPOINT IS VALID AGAIN*/ /*Check if we are initialized*/ if (mySize_ == 0) { mySize_ = 1; myData_ = new T*[mySize_]; } /*Check if we have place to insert obj in.*/ if (myIndex_ < mySize_) { myData_[myIndex_++] = new T(obj); return; } /*We didn't have enough place...*/ T** tmp = new T*[mySize_];//for copying old to temporary basket std::copy(&myData_[0],&myData_[mySize_],&tmp[0]); delete myData_; auto oldSize = mySize_; mySize_ *= 2; myData_ = new T*[mySize_]; std::copy(&tmp[0],&tmp[oldSize],&myData_[0]); myData_[myIndex_] = new T(obj); ++myIndex_; } #pragma endregion Thanks.

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  • How do i get file path of my file in java enterprise application?

    - by Nitesh Panchal
    Hello, I created java enterprise application and it consists of ejb module and web application. I have plain old xml file in source packages folder in package "common" in my ejb module. I want to pass this file path in File() constructor for one class in ejb module. How do i do it? If i pass any of the below it doesn't work :- new File("abc.xml"); //this take file from glassfish/domains/domain1 :( new File("./abc.xml"); I don't want to pass hardcode path like /home/administrator/appname/module/etc.. I want the path relative from my ejb module. Please help me. I've tried all things. Actually when i created a class in same folder and then try classname.getResource("abc.xml").getPath() it works fine. But what if i don't have any class in that folder. Waiting for your replies

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  • Online job-searching is tedious. Help me automate it.

    - by ehsanul
    Many job sites have broken searches that don't let you narrow down jobs by experience level. Even when they do, it's usually wrong. This requires you to wade through hundreds of postings that you can't apply for before finding a relevant one, quite tedious. Since I'd rather focus on writing cover letters etc., I want to write a program to look through a large number of postings, and save the URLs of just those jobs that don't require years of experience. I don't require help writing the scraper to get the html bodies of possibly relevant job posts. The issue is accurately detecting the level of experience required for the job. This should not be too difficult as job posts are usually very explicit about this ("must have 5 years experience in..."), but there may be some issues with overly simple solutions. In my case, I'm looking for entry-level positions. Often they don't say "entry-level", but inclusion of the words probably means the job should be saved. Next, I can safely exclude a job the says it requires "5 years" of experience in whatever, so a regex like /\d\syears/ seems reasonable to exclude jobs. But then, I realized some jobs say they'll take 0-2 years of experience, matches the exclusion regex but is clearly a job I want to take a look at. Hmmm, I can handle that with another regex. But some say "less than 2 years" or "fewer than 2 years". Can handle that too, but it makes me wonder what other patterns I'm not thinking of, and possibly excluding many jobs. That's what brings me here, to find a better way to do this than regexes, if there is one. I'd like to minimize the false negative rate and save all the jobs that seem like they might not require many years of experience. Does excluding anything that matches /[3-9]\syears|1\d\syears/ seem reasonable? Or is there a better way? Training a bayesian filter maybe?

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  • TStringList and TThread that does not free all of its memory

    - by VanillaH
    Version used: Delphi 7. I'm working on a program that does a simple for loop on a Virtual ListView. The data is stored in the following record: type TList=record Item:Integer; SubItem1:String; SubItem2:String; end; Item is the index. SubItem1 the status of the operations (success or not). SubItem2 the path to the file. The for loop loads each file, does a few operations and then, save it. The operations take place in a TStringList. Files are about 2mb each. Now, if I do the operations on the main form, it works perfectly. Multi-threaded, there is a huge memory problem. Somehow, the TStringList doesn't seem to be freed completely. After 3-4k files, I get an EOutofMemory exception. Sometimes, the software is stuck to 500-600mb, sometimes not. In any case, the TStringList always return an EOutofMemory exception and no file can be loaded anymore. On computers with more memory, it takes longer to get the exception. The same thing happens with other components. For instance, if I use THTTPSend from Synapse, well, after a while, the software cannot create any new threads because the memory consumption is too high. It's around 500-600mb while it should be, max, 100mb. On the main form, everything works fine. I guess the mistake is on my side. Maybe I don't understand threads enough. I tried to free everything on the Destroy event. I tried FreeAndNil procedure. I tried with only one thread at a time. I tried freeing the thread manually (no FreeOnTerminate...) No luck. So here is the thread code. It's only the basic idea; not the full code with all the operations. If I remove the LoadFile prodecure, everything works good. A thread is created for each file, according to a thread pool. unit OperationsFiles; interface uses Classes, SysUtils, Windows; type TOperationFile = class(TThread) private Position : Integer; TPath, StatusMessage: String; FileStringList: TStringList; procedure UpdateStatus; procedure LoadFile; protected procedure Execute; override; public constructor Create(Path: String; LNumber: Integer); end; implementation uses Form1; procedure TOperationFile.LoadFile; begin try FileStringList.LoadFromFile(TPath); // Operations... StatusMessage := 'Success'; except on E : Exception do StatusMessage := E.ClassName; end; end; constructor TOperationFile.Create(Path : String; LNumber: Integer); begin inherited Create(False); TPath := Path; Position := LNumber; FreeOnTerminate := True; end; procedure TOperationFile.UpdateStatus; begin FileList[Position].SubItem1 := StatusMessage; Form1.ListView4.UpdateItems(Position,Position); end; procedure TOperationFile.Execute; begin FileStringList:= TStringList.Create; LoadFile; Synchronize(UpdateStatus); FileStringList.Free; end; end. What could be the problem? I thought at one point that, maybe, too many threads are created. If a user loads 1 million files, well, ultimately, 1 million threads is going to be created -- although, only 50 threads are created and running at the same time. Thanks for your input.

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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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  • Performance of a get unique elements/group by operation on an IEnumerable<T>.

    - by tolism7
    I was wondering how could I improve the performance of the following code: public class MyObject { public int Year { get; set; } } //In my case I have 30000 IEnumerable<MyObject> data = MethodThatReturnsManyMyObjects(); var groupedByYear = data.GroupBy(x => x.Year); //Here is the where it takes around 5 seconds foreach (var group in groupedByYear) //do something here. The idea is to get a set of objects with unique year values. In my scenario there are only 6 years included in the 30000 items in the list so the foreach loop will be executed 6 times only. So we have many items needing to be grouped in a few groups. Using the .Distinct() with an explicit IEqualityComparer would be an alternative but somehow I feel that it wont make any difference. I can understand if 30000 items is too much and that i should be happy with the 5 seconds I get, but I was wondering if the above can be imporved performance wise. Thanks.

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  • C# Inherited member variables behaving undexpectedly

    - by Nilbert
    If I have a class like this: class A { public string fe = "A"; } And a class that inherits from it like so: class B : A { public string fe = "B"; } Visual C++ will tell me that B.fe hides A.fe so I should use the new keyword. So I change class B to look like: class B : A { public new string fe = "B"; } And then I have a function that takes an A (but, by virtue of inheritance, will also take a B) like this: class D { public static void blah(A anAObject) { Console.Writeline(A.fe); } } Even when I pass it an instance of a B object, which it will take without question, it will print "A"! Why is this, and how can I make it work how I want without setting the variable in the constructor?

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  • Best practice for passing configuration to each GUI object

    - by Laimoncijus
    Hi, I am writing an application, where I do have few different windows implemented, where each window is a separate class. Now I need somehow to pass a single configuration object to all of them. My GUI is designed in way, where I have one main window, which may create some child windows of its own, and these child windows can have their own childs (so there is no possibility to create all windows in initialization part and feed the config object to all of them from the very beginning)... What would be best practice for sharing this configuration object between them? Always passing via constructor or maybe making it somewhere as final public static and let each window object to access it when needed? Thanks

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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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  • WPF MVVM - Correct way to consume a web service asynchronously

    - by byte
    I have implemented MVVM in my WPF application. I was wondering what is the correct way to consume a Web Service from WPF MVVM app. So far, I have created a DataAccess interface and a class that implements this interface. This would serve as a facade / proxy to the web service. The ViewModel gets a reference to this class as the constructor parameter so it can make any calls to get/set data, in this case it will be a Web service call. I would appreciate if you can guide me with some hints and / or direct me to some online resource.

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  • error: expected ',' or '...' before numeric constant

    - by goldfrapp04
    Just a Qt Gui Application with QDialog as the Base Class, the simplest type you can expect. I've programmed on Qt for several times but this is the first time I meet this problem... I've added minimal code to the program, and here's the code in dialog.h (which is mostly automatically generated) #ifndef DIALOG_H #define DIALOG_H #include <QDialog> #include <QPixmap> #include "bmp.h" namespace Ui { class Dialog; } class Dialog : public QDialog { Q_OBJECT public: explicit Dialog(QWidget *parent = 0); ~Dialog(); private slots: void on_openButton_clicked(); private: Ui::Dialog *ui; BMP srcImage; QImage compressedImage[3]; }; #endif // DIALOG_H While I edit, the "public:" is underlined and says "unexpected token '('". When I try to build the program, it says in the line "Q_OBJECT", "error: expected ',' or '...' before numeric constant". I'm sure I've defined nothing related to it (to be exact, I defined an N and an n in file bmp.h, both are int). Any idea of what's wrong here? Thanks.

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  • How to overload shutdown function?

    - by Michal M
    I am using Kohana (v3) framework but I believe it's not tied to a particular framework. What I have is basically an app with a front-end, where I want to use Kohana's native Kohana::shutdown_handler(), but I also have a part of the - RESTful API - where I don't want colourful and html-encoded exception reporting. I want a plain text reporting. The way I thought it might work is to register another shutdown function in API's controller abstract class constructor, but then I realised register_shutdown_function() works differently to set_exception_handler() and instead of replacing it adds another function to the shutdown procedure. What's worse PHP doesn't allow "unregistering" shutdown functions and that's where my problem lies. What to do, if you want to use another shutdown function instead of one already registered?

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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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  • Explanation of output

    - by Anon
    My program class Building { Building() { System.out.print("b "); } Building(String name) { this(); System.out.print("bn " + name); } }; public class House extends Building { House() { System.out.print("h "); // this is line# 1 } House(String name) { this(); // This is line#2 System.out.print("hn " + name); } public static void main(String[] args) { new House("x "); } } We know that compiler will write a call to super() as the first line in the child class's constructor. Therefore should not the output be: b (call from compiler written call to super(), before line#2 b (again from compiler written call to super(),before line#1 ) h hn x But the output is b h hn x Why is that?

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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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