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Search found 3956 results on 159 pages for 'constructor overloading'.

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  • intiating lists in the constructor's initialization list

    - by bks
    i just moved from C to C++, and now work with lists. i have a class called "message", and i need to have a class called "line", which should have a list of messages in its properties. as i learned, the object's properties should be initialized in the constructor's initialization list, and i had the "urge" to initialize the messages list in addition to the rest of the properties (some strings and doubles). is that "urge" justified? does the list need to be initialized? thank you in advance

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  • What the purpose/difference in using an event-type constructor

    - by phq
    In all examples I can find as well as the automatically generated code i Visual Studio, events are set using the following code: button1.Click += new System.EventHandler(this.button1_Click); But I can also write it visually cleaner by omitting the constructor wrapper: button1.Click += this.button1_Click; Which also compile fine. What is the difference between these two? And why is the first one mostly used/preferred?

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  • variable scope when adding a value to a vector in class constructor

    - by TheFuzz
    I have a level class and a Enemy_control class that is based off an vector that takes in Enemys as values. in my level constructor I have: Enemy tmp( 1200 ); enemys.Add_enemy( tmp ); // this adds tmp to the vector in Enemy_control enemys being a variable of type Enemy_control. My program crashes after these statements complaining about some destructor problem in level and enemy_control and enemy. Any ideas?

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  • (Strange) C++ linker error in constructor

    - by Microkernel
    I am trying to write a template class in C++ and getting this strange linker error and can't figureout the cause, please let me know whats wrong with this! Here is the error message I am getting in Visula C++ 2010. 1>------ Rebuild All started: Project: FlashEmulatorTemplates, Configuration: Debug Win32 ------ 1> main.cpp 1> emulator.cpp 1> Generating Code... 1>main.obj : error LNK2019: unresolved external symbol "public: __thiscall flash_emulator<char>::flash_emulator<char>(char const *,struct FLASH_PROPERTIES *)" (??0?$flash_emulator@D@@QAE@PBDPAUFLASH_PROPERTIES@@@Z) referenced in function _main 1>C:\Projects\FlashEmulator_templates\VS\FlashEmulatorTemplates\Debug\FlashEmulatorTemplates.exe : fatal error LNK1120: 1 unresolved externals ========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ========== Error message in g++ main.cpp: In function âint main()â: main.cpp:8: warning: deprecated conversion from string constant to âchar*â /tmp/ccOJ8koe.o: In function `main': main.cpp:(.text+0x21): undefined reference to `flash_emulator<char>::flash_emulator(char*, FLASH_PROPERTIES*)' collect2: ld returned 1 exit status There are 2 .cpp files and 1 header file, and I have given them below. emulator.h #ifndef __EMULATOR_H__ #define __EMULATOR_H__ typedef struct { int property; }FLASH_PROPERTIES ; /* Flash emulation class */ template<class T> class flash_emulator { private: /* Private data */ int key; public: /* Constructor - Opens an existing flash by name flashName or creates one with given FLASH_PROPERTIES if it doesn't exist */ flash_emulator( const char *flashName, FLASH_PROPERTIES *properties ); /* Constructor - Opens an existing flash by name flashName or creates one with given properties given in configFIleName */ flash_emulator<T>( char *flashName, char *configFileName ); /* Destructor for the emulator */ ~flash_emulator(){ } }; #endif /* End of __EMULATOR_H__ */ emulator.cpp #include <Windows.h> #include "emulator.h" using namespace std; template<class T>flash_emulator<T>::flash_emulator( const char *flashName, FLASH_PROPERTIES *properties ) { return; } template<class T>flash_emulator<T>::flash_emulator(char *flashName, char *configFileName) { return; } main.cpp #include <Windows.h> #include "emulator.h" int main() { FLASH_PROPERTIES properties = {0}; flash_emulator<char> myEmulator("C:\newEMu.flash", &properties); return 0; }

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  • SharePoint Web Part Constructor Fires Twice When Adding it to the Page (and has a different security

    - by Damon
    We had some exciting times debugging an interesting issue with SharePoint 2007 Web Parts.  We had some code in staging that had been running just fine for weeks and had not been touched or changed in about the same amount of time.  However, when we tried to move the web part into a different staging environment, the part started throwing a security exception when we tried to add it to a page.  After a bit of debugging, we determined that the web part was throwing the exception while trying to access the SPGroups property on the SharePoint site.  This was pretty strange because we were logged in as an admin and the code was working perfectly fine before.  During the debugging process, however, we found out that the web part constructor was being fired twice.  On one request, the security context did not seem to have everything it needed in order to run.  On the other request, the security context was populated with the user context with the user making the request (like it normally is).  Moving the security code outside of the constructor seems to have fixed the issue. Why the discrepancy between the two staging environments?  Turns out we deployed the part originally, then deployed an update with the security code.  Since the part was never "added" to the page after the code updates were made (we just deployed a new assembly to make the updates), we never saw the problem.  It seems as though the constructor fires twice when you are adding the web part to the page, and when you run the web part from the web part gallery.  My only thought on why this would occur is that SharePoint is instantiating an instance to get some information from it - which is odd because you would think that would happen with reflection without requiring a new object.  Anyway, the work around is to just not put anything security related inside the constructor, or to do a good job accounting for the possibility of the security context not being present if you are adding the item to the page. Technorati Tags: SharePoint,.NET,Microsoft,ASP.NET

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  • Why a static main method in Java and C#, rather than a constructor?

    - by Konrad Rudolph
    Why did (notably) Java and C# decide to have a static method as their entry point – rather than representing an application instance by an instance of an Application class, with the entry point being an appropriate constructor which, at least to me, seems more natural? I’m interested in a definitive answer from a primary or secondary source, not mere speculations. This has been asked before. Unfortunately, the existing answers are merely begging the question. In particular, the following answers don’t satisfy me, as I deem them incorrect: There would be ambiguity if the constructor were overloaded. – In fact, C# (as well as C and C++) allows different signatures for Main so the same potential ambiguity exists, and is dealt with. A static method means no objects can be instantiated before so order of initialisation is clear. – This is just factually wrong, some objects are instantiated before (e.g. in a static constructor). So they can be invoked by the runtime without having to instantiate a parent object. – This is no answer at all. Just to justify further why I think this is a valid and interesting question: Many frameworks do use classes to represent applications, and constructors as entry points. For instance, the VB.NET application framework uses a dedicated main dialog (and its constructor) as the entry point1. Neither Java nor C# technically need a main method. Well, C# needs one to compile, but Java not even that. And in neither case is it needed for execution. So this doesn’t appear to be a technical restriction. And, as I mentioned in the first paragraph, for a mere convention it seems oddly unfitting with the general design principle of Java and C#. To be clear, there isn’t a specific disadvantage to having a static main method, it’s just distinctly odd, which made me wonder if there was some technical rationale behind it. I’m interested in a definitive answer from a primary or secondary source, not mere speculations. 1 Although there is a callback (Startup) which may intercept this.

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  • How can I pass an external instance to the constructor of an object that's being created using the default XNA XML content loader?

    - by Michael
    I'm trying to understand how to use the XNA XML content importer to instantiate non-trivial objects that are more than a collection of basic properties (e.g., a class that inherits from DrawableGameObject or GameObject and requires other things to be passed into its constructor). Is it possible to pass existing external instances (e.g., an instance of the current Game) to the constructor of an object that's being created using the default XNA XML content loader? For example, imagine that I have the following class, inheriting from DrawableGameComponent: public class Character : DrawableGameComponent { public string Name { get; set; } public Character(Game game) : base(game) { } public override void Update(GameTime gameTime) { } public override void Draw(GameTime gameTime) { } } If I had a simple class that did not need other parameters in its constructor (i.e., the Game instance), then I could simply use this XML: <XnaContent> <Asset Type="MyNamespace.Character"> <Name>John Doe</Name> </Asset> </XnaContent> ...and then create an instance of Character using this code: var character = Content.Load<Character>("MyXmlAssetName"); But that won't work because I need to pass the need to pass the Game into the constructor. What's the best way to handle this situation? Is there a way to pass in things like the current Game using the default XNA XML content loader? Do I need to write my own XML loader? (If so, how?) Is there a better object-oriented design that I should be using for my classes? Note: Although I used Game in this example, I'm really just asking how to pass any type of existing instance to my constructors. (For example, I'm using the Farseer Physics Engine, and some of my classes also need a reference to the Farseer World object too.) Thanks in advance.

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  • I need an abstract field !

    - by Jules Olléon
    I know abstract fields do not exist in java. I also read this question but the solutions proposed won't solve my problem. Maybe there is no solution, but it's worth asking :) Problem I have an abstract class that does an operation in the constructor depending on the value of one of its fields. The problem is that the value of this field will change depending on the subclass. How can I do so that the operation is done on the value of the field redefined by the subclass ? If I just "override" the field in the subclass the operation is done on the value of the field in the abstract class. I'm open to any solution that would ensure that the operation will be done during the instantiation of the subclass (ie putting the operation in a method called by each subclass in the constructor is not a valid solution, because someone might extend the abstract class and forget to call the method). Also, I don't want to give the value of the field as an argument of the constructor. Is there any solution to do that, or should I just change my design ?

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  • Why does a sub-class class of a class have to be static in order to initialize the sub-class in the

    - by Alex
    So, the question is more or less as I wrote. I understand that it's probably not clear at all so I'll give an example. I have class Tree and in it there is the class Node, and the empty constructor of Tree is written: public class RBTree { private RBNode head; public RBTree(RBNode head,RBTree leftT,RBTree rightT){ this.head=head; this.head.leftT.head.father = head; this.head.rightT.head.father = head; } public RBTree(RBNode head){ this(head,new RBTree(),new RBTree()); } public RBTree(){ this(new RBNode(),null,null); } public class RBNode{ private int value; private boolean isBlack; private RBNode father; private RBTree leftT; private RBTree rightT; } } Eclipse gives me the error: "No enclosing instance of type RBTree is available due to some intermediate constructor invocation" for the "new RBTree()" in the empty constructor. However, if I change the RBNode to be a static class, there is no problem. So why is it working when the class is static. BTW, I found an easy solution for the cunstructor: public RBTree(){ this.head = new RBNode(); } So, I have no idea what is the problem in the first piece of code.

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  • struct constructor + function parameter

    - by Oops
    Hi, I am a C++ beginner. I have the following code, the reult is not what I expect. The question is why, resp. what is wrong. For sure, the most of you see it at the first glance. struct Complex { float imag; float real; Complex( float i, float r) { imag = i; real = r; } Complex( float r) { Complex(0, r); } std::string str() { std::ostringstream s; s << "imag: " << imag << " | real: " << real << std::endl; return s.str(); } }; class Complexes { std::vector<Complex> * _complexes; public: Complexes(){ _complexes = new std::vector<Complex>; } void Add( Complex elem ) { _complexes->push_back( elem ); } std::string str( int index ) { std::ostringstream oss; Complex c = _complexes->at(index); oss << c.str(); return oss.str(); } }; int main(){ Complexes * cs = new Complexes(); //cs->Add(123.4f); cs->Add(Complex(123.4f)); std::cout << cs->str(0); return 0; } for now I am interested in the basics of c++ not in the complexnumber theory ;-) it would be nice if the "Add" function does also accept one real (without an extra overloading) instead of only a Complex-object is this possible? many thanks in advance Oops

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  • NUll exception in filling a querystring by mocing framework

    - by user564101
    There is a simple controller that a querystring is read in constructor of it. public class ProductController : Controller { parivate string productName; public ProductController() { productName = Request.QueryString["productname"]; } public ActionResult Index() { ViewData["Message"] = productName; return View(); } } Also I have a function in unit test that create an instance of this Controller and I fill the querystring by a Mock object like below. [TestClass] public class ProductControllerTest { [TestMethod] public void test() { // Arrange var querystring = new System.Collections.Specialized.NameValueCollection { { "productname", "sampleproduct"} }; var mock = new Mock<ControllerContext>(); mock.SetupGet(p => p.HttpContext.Request.QueryString).Returns(querystring); var controller = new ProductController(); controller.ControllerContext = mock.Object; // Act var result = controller.Index() as ViewResult; // Assert Assert.AreEqual("Index", result.ViewName); } } Unfortunately Request.QueryString["productname"] is null in constructor of ProductController when I run test unit. Is ther any way to fill a querystrin by a mocking and get it in constructor of a control?

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  • steam condenser java errors

    - by w0rm
    I've been working on a little project involving Steam Condenser, a Steam API written in Java, but I haven't been able to actually do anything with it. I'll explain. This is what the wiki tells me: SteamId id = new SteamId("demomenz"); GameStats stats = id.getGameStats("tf2"); List achievements = stats.getAchievements(); The problem is, eclipse doesn't like it apparently, as it spits out this error: The constructor SteamId(String) is undefined and it gives me the option to change it to: SteamId id = new SteamId("demomenz", false); But at this point a different error comes out: The constructor SteamId(Object, boolean) is not visible So, I'm assuming this function is internal to the API, and should not be called from the outside. If anyone is familiar with this, or has a clue on why I'm getting this error (I'm fairly new to Java development), an answer would be greatly appreciated. UPDATE: The constructor SteamId(String) is undefined This is if I use SteamId.create(ConvertedID); (ConvertedID is a String containing the Steam64 ID). At this point I believe this API is not that well written, at least for java. Any other idea?

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  • Resolve dependency with autofac based on constructor parameter attribute

    - by Andrew Davey
    I'm using AutoFac. I want to inject a different implementation of a dependency based on an attribute I apply to the constructor parameter. For example: class CustomerRepository { public CustomerRepository([CustomerDB] IObjectContainer db) { ... } } class FooRepository { public FooRepository([FooDB] IObjectContainer db) { ... } } builder.Register(c => /* return different instance based on attribute on the parameter */) .As<IObjectContainer>(); The attributes will be providing data, such as a connection string, which I can use to instance the correct object. How can I do this?

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  • StructureMap : How to define default constructor by code ?

    - by cik
    Hi, I can't figure out how to define the default constructor (when it exists overloads) for a type in StructureMap (version 2.5) by code. I want to get an instance of a service and the container has to inject a Linq2Sql data context instance into it. I wrote this in my 'bootstrapper' method : ForRequestedType<MyDataContext>().TheDefault.Is.OfConcreteType<MyDataContext>(); When I run my app, I got this error : StructureMap Exception Code: 202 No Default Instance defined for PluginFamily MyNamespace.Data.SqlRepository.MyDataContext, MyNamespace.Data, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null If I comment out all Linq2Sql generated contructors that I don't need, it works fine. Update : Oh, and I forgot to say that I would not use the [StructureMap.DefaultConstructor] attribute.

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  • Error using traits class.: "expected constructor destructor or type conversion before '&' token"

    - by Mark
    I have a traits class that's used for printing out different character types: template <typename T> class traits { public: static std::basic_ostream<T>& tout; }; template<> std::ostream& traits<char>::tout = std::cout; template<> std::wostream& traits<unsigned short>::tout = std::wcout; gcc (g++) version 3.4.5 (yes somewhat old) is throwing an error: "expected constructor destructor or type conversion before '&' token" And I'm wondering if there's a good way to resolve this. (it's also angry about _O_WTEXT so if anyone's got some insight into that, I'd also appreciate it)

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  • constructor injection using Autofac 2 and Named Registration

    - by Thad
    I am currently attempting to remove a number of .Resolve(s) in our code. I was moving along fine until I ran into a named registration and I have not been able to get Autofac resolve using the name. What am I missing to get the named registration injected into the constructor. Registration builder.RegisterType<CentralDataSessionFactory>().Named<IDataSessionFactory>("central").SingleInstance(); builder.RegisterType<ClientDataSessionFactory>().Named<IDataSessionFactory>("client").SingleInstance(); builder.RegisterType<CentralUnitOfWork>().As<ICentralUnitOfWork>().InstancePerDependency(); builder.RegisterType<ClientUnitOfWork>().As<IClientUnitOfWork>().InstancePerDependency(); Current class public class CentralUnitOfWork : UnitOfWork, ICentralUnitOfWork { protected override ISession CreateSession() { return IoCHelper.Resolve<IDataSessionFactory>("central").CreateSession(); } } Would Like to Have public class CentralUnitOfWork : UnitOfWork, ICentralUnitOfWork { private readonly IDataSessionFactory _factory; public CentralUnitOfWork(IDataSessionFactory factory) { _factory = factory; } protected override ISession CreateSession() { return _factory.CreateSession(); } }

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  • Boost::Interprocess Container Container Resizing No Default Constructor

    - by CuppM
    Hi, After combing through the Boost::Interprocess documentation and Google searches, I think I've found the reason/workaround to my issue. Everything I've found, as I understand it, seems to be hinting at this, but doesn't come out and say "do this because...". But if anyone can verify this I would appreciate it. I'm writing a series of classes that represent a large lookup of information that is stored in memory for fast performance in a parallelized application. Because of the size of data and multiple processes that run at a time on one machine, we're using Boost::Interprocess for shared memory to have a single copy of the structures. I looked at the Boost::Interprocess documentation and examples, and they typedef classes for shared memory strings, string vectors, int vector vectors, etc. And when they "use" them in their examples, they just construct them passing the allocator and maybe insert one item that they've constructed elsewhere. Like on this page: http://www.boost.org/doc/libs/1_42_0/doc/html/interprocess/allocators_containers.html So following their examples, I created a header file with typedefs for shared memory classes: namespace shm { namespace bip = boost::interprocess; // General/Utility Types typedef bip::managed_shared_memory::segment_manager segment_manager_t; typedef bip::allocator<void, segment_manager_t> void_allocator; // Integer Types typedef bip::allocator<int, segment_manager_t> int_allocator; typedef bip::vector<int, int_allocator> int_vector; // String Types typedef bip::allocator<char, segment_manager_t> char_allocator; typedef bip::basic_string<char, std::char_traits<char>, char_allocator> string; typedef bip::allocator<string, segment_manager_t> string_allocator; typedef bip::vector<string, string_allocator> string_vector; typedef bip::allocator<string_vector, segment_manager_t> string_vector_allocator; typedef bip::vector<string_vector, string_vector_allocator> string_vector_vector; } Then for one of my lookup table classes, it's defined something like this: class Details { public: Details(const shm::void_allocator & alloc) : m_Ids(alloc), m_Labels(alloc), m_Values(alloc) { } ~Details() {} int Read(BinaryReader & br); private: shm::int_vector m_Ids; shm::string_vector m_Labels; shm::string_vector_vector m_Values; }; int Details::Read(BinaryReader & br) { int num = br.ReadInt(); m_Ids.resize(num); m_Labels.resize(num); m_Values.resize(num); for (int i = 0; i < num; i++) { m_Ids[i] = br.ReadInt(); m_Labels[i] = br.ReadString().c_str(); int count = br.ReadInt(); m_Value[i].resize(count); for (int j = 0; j < count; j++) { m_Value[i][j] = br.ReadString().c_str(); } } } But when I compile it, I get the error: 'boost::interprocess::allocator<T,SegmentManager>::allocator' : no appropriate default constructor available And it's due to the resize() calls on the vector objects. Because the allocator types do not have a empty constructor (they take a const segment_manager_t &) and it's trying to create a default object for each location. So in order for it to work, I have to get an allocator object and pass a default value object on resize. Like this: int Details::Read(BinaryReader & br) { shm::void_allocator alloc(m_Ids.get_allocator()); int num = br.ReadInt(); m_Ids.resize(num); m_Labels.resize(num, shm::string(alloc)); m_Values.resize(num, shm::string_vector(alloc)); for (int i = 0; i < num; i++) { m_Ids[i] = br.ReadInt(); m_Labels[i] = br.ReadString().c_str(); int count = br.ReadInt(); m_Value[i].resize(count, shm::string(alloc)); for (int j = 0; j < count; j++) { m_Value[i][j] = br.ReadString().c_str(); } } } Is this the best/correct way of doing it? Or am I missing something. Thanks!

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  • constructor in Perl with an array(OOPS)

    - by superstar
    whats the difference between these two 'new' constructors in perl? 1) sub new { my $class = shift; my $self = {}; $self->{firstName} = undef; $self->{lastName} = undef; $self->{PEERS} = []; bless ($self, $class); return $self; } 2) sub new { my $class = shift; my $self = { _firstName => shift, _lastName => shift, _ssn => shift, }; bless $self, $class; return $self; } I am using the 2nd one so far, but i need to implement the arrays in perl? can you suggest a way to do it with the 2nd 'new' constructor

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