It implements a strong smart pointer class, sharing the pointer . Create an object, and then use the serializer as follows:. It is ok to obtain the value of the pointer and using that value itself,. Examples at hotexamples. centralwidget = std::make_shared<QWidget> (MainWindow); verticalLayout = std::make_shared<QVBoxLayout> (centralwidget. QSharedPointer will delete the pointer it is holding when it goes out of scope, provided no other QSharedPointer objects are referencing it. It's a start. C++ (Cpp) QSharedPointer Examples. If used in this way, you can pass around these references and use them like pointers, and. The QSharedPointer is an automatic, shared pointer in C++. The Qt docs say that Q_DECLARE_METATYPE is necessary in case one has a connect being a queued connection. append(QSharedPointer<MyObject>(new MyObject("second", 2))); Share. The pointer ptr becomes managed by this QSharedPointer and must not be passed to another QSharedPointer object or deleted. C++ (Cpp) QSharedPointer::getShapes - 4 examples found. The base class of all event classes. LMNode::setParent(const QSharedPointer<LMNode>& parent) { this->parent = parent; } const QSharedPointer<LMNode>& LMNode::getParent() { return this->parent; } Sure, in the second version i avoid the increment of the reference counter and the changing of the QSharedPointer object. The normal pattern is to put the new statement inside the smart pointer's constructor, like this: QSharedPointer<Obj> p (new Obj (2)); That way you never have a reference to the naked pointer itself. But everytime i try to implement this i recieve a seg fault. You might be tempted to use QSharedPointer in this case and it would work, but remember that QSharedPointer, just like std::shared_ptr, is a lot heavier construct, as sharing in a multi-threaded world is a "far from 0" overhead thing. #include <QSharedPointer> #include <memory> QSharedPointer<int> answer1. It. Qt Blocking Queue. This is the pattern that the automatic data collector will look for and parse. The QWeakPointer is an automatic weak reference to a pointer in C++. It is a bug if you put just a pointer to your item to QChache and at the same time such pointer is managed by QSharedPointer. GetInfo(9) GetRemoteId(8) AddChildren(5) GetP1(5). This QCPAxisTicker subclass generates ticks with a fixed tick step set with setTickStep. Purpose. The QSharedPointer is an automatic, shared pointer in C++. when I will print the debug message second time it shows the segmentation fault and application crashes. It stores its items in adjacent memory locations and provides fast index-based access. 6. You can however easily fix that by creating a new shared pointer instance for each sample and pass that one to the other thread in the signal. Commented defines are for "not compiling" parts. I like passing data between threads using QSharedDataPointer or QSharedPointer. QSharedPointer will attempt to perform an automatic t static_cast. QSharedPointer < T > QEnableSharedFromThis:: sharedFromThis () If this (that is, the subclass instance invoking this method) is being managed by a QSharedPointer, returns a shared pointer instance pointing to this; otherwise returns a null QSharedPointer. docx from EEET 1026 at University of South Australia. M. Axis tickers are commonly created managed by a QSharedPointer, which then can be passed to QCPAxis::setTicker. I read the documentation, searched for examples which fit my needs and experimented with QScoped and QSharedPointer, but couldn't find a fullfilling solution for me. Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. [quote author="Andre" date="1306394817"]In that case, I think you need to register them. This helps. I am using Qt 5. The QSharedPointer class holds a strong reference to a shared pointer. You can rate examples to help us improve the quality of examples. Since display() is part of the class's interface with the rest of the program, the slot is public. But I've not seen it much in use in source code of Examples and Demos. in Qt-using projects. cpp MainWindow::MainWindow () :timer2 (new QTimer) { } Alternately, if you want to create the instance in some arbitrary member function of MainWindow, use this: It's also worth reviewing initialization lists in C++ and the documentation for QScopedPointer. The QSharedPointer is an automatic, shared pointer in C++. So, at least, QList and QVector can be filled with it (I am not trying to find high-speed approach). The one I used in my own answer does. See QWeakPointer::toStrongRef () for an example. To avoid the cost of thread creation, a thread pool can be used. When a QObject is destroyed, it in turn destroys all objects it owns. It behaves exactly like a normal pointer for normal purposes, including respect for constness. In the example above, the template specialization for the clone() function calls the EmployeeData::clone() virtual function. Also if you had been used raw pointers in QList it would not work because you can not overwrite the == operator of the raw pointer (you. Maybe I have bad expressed. 04 OS. These are the top rated real world C++ (Cpp) examples of QSharedPointer::at extracted from open source projects. Note that if you intend to use the type in queued signal and slot connections or in QObject's property system, you. An. There are not so much Qt examples and demos with QSharedPointer because of the general concept for memory management in Qt using parent–child hierarchy of QObject. removeAll(dataPoint01); }. Note that if you intend to use the type in queued signal and slot connections or in QObject's property system, you also have to call. 1009. Example: QPointer < QLabel > label = new QLabel ; label - > setText( "&Status:" );. template<class T> QSharedPointer<T> I checked a bit on StackOverflow but others examples are really complicated. These are the top rated real world C++ (Cpp) examples of QSharedPointer::GetFormulaRadius extracted from open source projects. . The temporary instance of the shared pointer allocated on the heap in answer1 will be deallocated by its shared pointer. In this example, the child thread waits for user clicking, then prints a message. The same is for tokencount == 1. Unfortunately Google was unable to help me this time. Before drawing you would create a local QSharedPointer<MyClass> in the drawing function and check if it is valid. . See also QSharedPointer and QScopedPointer. 5k 15 97 178. A minimal example: Q_DECLARE_METATYPE(QSharedPointer<const QObject>);One example may be the case where you store lots of pointers to objects in a container class. QVector<T> used to be a different class in Qt 5, but is now a simple alias to QList. Usually one puts this (note that the typedefed name is used as string argument): qRegisterMetaType < QSharedPointer < TestClass > > ( "SharedTestClass" );Qt also provides QSharedPointer, an implementation of a reference-counted shared pointer object, which can be used to maintain a collection of references to an individual pointer. This class is used as an index into item models derived from QAbstractItemModel. referencing it. h: > > // ### Qt6: Using a private here has high impact on runtime > // on users such as QFileInfo. Does my QSharedPointer is always valid ? What append if during processing (MainWindow), the usb_read() occurs and the memcpy write on my image. Programming language: C++ (Cpp) Class/type: QSharedPointer Therefore, to access the pointer that QWeakPointer is tracking, you must first promote it to QSharedPointer and verify if the resulting object is null or not. 9 on Ubuntu 18. If you refactor your code so that all new operator are in lines like these, all your problems will be solved. As reference the example tested on cross environment using GDB:Here is a minimal example: #include <QSharedPointer> struct A {}; int main(int argc, char *argv[]) { auto ca = QSharedPointer<const A>::create(); return 0; } Here is one file (not minimal) example but with few working cases, 2 not working and a debug. at (x); Then I pass it around and do the work, then the pointer dies but I have an extra one in the list so everything's fine, right? I noticed the destructor of MyClass is. It's possible that your first thread will execute the if statement, then the other thread will delete your label, and then you will be inside of your if statement and crash. The one I used in my own answer does. /blocking_queue. It behaves exactly like a normal pointer for normal purposes, including respect for constness. See QWeakPointer::toStrongRef () for an example. Values stored in Qt containers should be of assignable data types. Returns a list of child objects. Qt 6 youtube videos by Bry. If somehow the object/container survives so does the smart pointer and the allocated memory. You can rate examples to help us improve the quality of examples. Purpose. QSharedPointer guarantees that the object isn't deleted, so if you obtain a non-null object, you may use the pointer. When an object gets deleted, either by delete childObject; or delete parentObject;, I would like the QSharedPointer instances to return true when calling isNull(). data(); delete obj; To copy to clipboard, switch view to plain text mode. When I try to simply connect signalslot with such QVector as argument programm tells during run that this metatype should be registered (though QVector, QSharedPointer and class inherited from QObject should be registered automatically. As reference the example tested on cross environment using GDB:Qt Base (Core, Gui, Widgets, Network,. You can rate examples to help us improve the quality of examples. How To Use Managed Pointers In C++ and Qt. Detailed Description The QSharedPointer class holds a strong reference to a shared pointer The QSharedPointer is an automatic, shared pointer in C++. A public static factory method returning in this case QSharedPointer; A private deleter class that is a friend of class A; Here is an example using boost::shared_ptr (I do not have a QT installation right now, but you should be able to just replace all instances of boost::shared_ptr with QSharedPointer)It is somehow reasonable to use QSharedPointer here. It should work if the code is put into one function block. Children are typically added to a QObject *parent from their constructor with new QObject(parent);. QSharedPointer: pointer 0x2384d70 already has reference counting Which at the very least gives us a basic idea that there is something wrong, and it involves a QSharedPointer. . These are the top rated real world C++ (Cpp) examples of QSharedPointer::at extracted from open source projects. The code below won't leak memory and doesn't invoke any undefined behavior. The QWeakPointer is QSharedPointer 's cousin. Extracts a directory from resources to disk. data (); } When you delete the pointed-to object, data () will be null. Specialized axis ticker with a fixed tick step. The QSharedPointer class holds a strong reference to a shared pointer More. These are the top rated real world C++ (Cpp) examples of QSharedPointer::getReferencedBlockId extracted from open source projects. 1) The compiler should be able to perfor RVO or std::move 2) Quite a few classes (especially containers, including QList) use Implicit Sharing i. . g. In this example, the source object is a simple binary switch that toggles its state based on a timer. Code that makes use of delete are candidates for QScopedPointer usage (and if not, possibly another type of smart pointer such as QSharedPointer). 1 Reply Last reply . I use C++17, GCC 7. You can rate examples to help us improve the quality of examples. . One example may be the case where you store lots of pointers to objects in a container class. 3 as published by the Free Software Foundation. staticCast<Switch> (); Both versions are basically equivalent to doing static_cast on raw pointers. For your concrete example, you could use a QList<QSharedPointer<MyClass>> for the model and use QWeakPointer<MyClass> in the drawable classes. }; Q_DECLARE_METATYPE (blabla) But this code is giving me Error: In copy constructor ‘QThread::QThread (const QThread&)’: instantiated from ‘void. template <typename InputIterator>. It behaves exactly like a normal pointer for normal purposes, including respect for constness. Commented defines are for "not compiling" parts. Log in JoinPimpl + QSharedPointer - Destructor = Disaster. I want to prevent something as this: Qt Code: Switch view. QPointer:: QPointer () Constructs a guarded pointer with value nullptr. Call doc:QSharedPointer :: data () to get a pointer to the referenced class; Make sure the QML engine doesn't assume ownership: doc:QDeclarativeEngine :: setObjectOwnership (P). 이는 표준 C++ std::shared_ptr 와 유사하지만 Qt 애플리케이션에 유용하게 만드는 몇 가지 추가 기능이 있습니다. That said, your stack trace is really strange:. Here be dragons! All Qt containers implement COW (Copy On Write). qRegisterMetaType< QSharedPointer<TestClass> >("SharedTestClass"); in main() not as a global variable. Assume that we have T convert_func (const QJsonValue& value),. These are the top rated real world C++ (Cpp) examples of QSharedPointer::update extracted from open source projects. For example, consider a segment which directly goes from region 4 to 2 but originally is far out to the top left such that it doesn't cross region 5. This allows a safely shared pointer that can be used on objects that get passed around by reference like in C#. You can inherit this class when you need to create a QSharedPointer from any instance of a class; for instance, from within the object itself. If somehow the object/container survives so does the smart pointer and the allocated memory. Example: QPointer < QLabel > label = new QLabel ; label - > setText( "&Status:" );. It behaves exactly like a normal pointer for normal purposes, including respect for constness. QPointer:: ~QPointer () Destroys the guarded pointer. A mutex is. The lifetime of an object begins after its constructor completes successfully. Resets this QSharedPointer object to point to t instead. It. I also want to keep track of some of the objects with QSharedPointer instances. Sorted by: 10. Detailed Description. The base class tick generator used by QCPAxis to create tick positions and tick labels. Show Hide. 12. QSharedPointer의 주요 기능 중 하나는 스레드로부터 안전하다는 것입니다. class QSharedPointer< T > The QSharedPointer class stores a pointer to a potentially shared object. For example i wanted to use a QsharedPointer<QStringListModel> instead of a QStringListModel* as a parameter for the function QListView::setModel. Since the ownership of most objects of Qt Promise is shared between multiple objects, the library uses Qt's smart pointer class QSharedPointer to manage the lifetime of the objects. behaves exactly like a normal pointer for normal purposes, including respect for constness. For some reason, there are very few examples out there on how to use QSharedPointer, so i find myself posting here. e. 1 Answer. This project implements the Event and BlockingQueue in two. . h" class Controller { private : QSharedPointer<MyClass. C++ (Cpp) QSharedPointer::StopTimer - 1 examples found. qRegisterMetaType< QSharedPointer<TestClass> >("SharedTestClass"); in main() not as a global variable. It behaves exactly like a normal pointer for normal purposes, including respect for constness. #include <QSharedPointer> #include <memory>. Adding a Q_DECLARE_METATYPE () makes the type known to all template based functions, including QVariant. That said, your stack trace is really strange:. args) \overload \since 5. 0, Qt 5. Therefore you have to create you smart pointer instance like this: auto obj=QSharedPointer<MyCustomObj>(new MyCustomObj,. It uses reference counting to track the number of objects sharing the pointer, and. Does it mean QSharedPointer<T>::create() is the preferred one?I want to create a QSharedPointer in one class and submit the data as a SIGNAL parameter: @emit mySignal((new MyClass). Also, by overloading the operator, it's very easy to. One place we have used QSharedPointer is in DataObjectTableModel, shown in Example 13. qt. But is there a stringent way how as I have to do?The QSharedPointer is an automatic, shared pointer in C++. : QFrame: Supports the box model. The whole point of this function is to allocate the reference count near the object instance in memory, so you have to let it do the allocation. template<typename T >. Make sure you declare the objects dynamically. You can rate examples to help us improve the quality of examples. In this episode we will look at two Qt smart pointers - QScopedPointer and QSharedPointer. h","path":"src/corelib/tools/qalgorithms. You can rate examples to help us improve the quality of examples. Detailed Description. The source can be found in the examples directory: examples/tutorials/threads/ Example 1: Using the Thread Pool. This is not only about the Qt framework but also the STL in general. QSharedPointer:: objectCast() works reliably across DLL boundaries, but QSharedPointer:: dynamicCast() and std::dynamic_pointer_cast() don’t. QSharedPointer<QMap<int, bool>> mpsptr = QSharedPointer<QMap<int, bool>>::create (QMap<int, bool> { {1, false}}); Ok, I found an answer that works for me. Call doc:QSharedPointer :: data () to get a pointer to the referenced class; Make sure the QML engine doesn't assume ownership: doc:QDeclarativeEngine :: setObjectOwnership (P). All of QList's functionality also applies to QQueue. This is a very safe way to. The same question about Qt equivalent - QSharedPointer. 27. >> I'm trying to use QMap/QHash with QSharedPointer with no success. The QPointer class is a template class that provides guarded pointers to QObject. You can rate examples to help us improve the quality of. What I did: @APIRequest::APIRequest () {. QSharedPointer. Previously i had done this: Qt Code: Switch view. It doesn't do any owning duties. However, by that time, a. The problem is, that when implementing a QSharedAbstractItemModel, like the QAbstractListModel, you need to deal with raw pointers. QSharedPointer will delete the pointer it is holding when it goes out of scope, provided no other. You can inherit this class when you need to create a QSharedPointer from any instance of a class; for instance, from within the object itself. For example, if %m is the largest unit it might become larger than 59 in order to consume larger time values. You can rate examples to. This class was introduced in Qt 4. Here is a minimal example: #include <QSharedPointer> struct A {}; int main(int argc, char *argv[]) { auto ca = QSharedPointer<const A>::create(); return 0; } Here is one file (not minimal) example but with few working cases, 2 not working and a debug. QScopedPointer intentionally has no copy constructor or assignment operator, such that ownership and. Since the replicas have the same properties, signals, and slots as were. When the code block containing ptr2 ends, its reference. The exception is pointers derived from QObject: in that. Test this small example: @ #include <QSharedPointer> class CTest {int INum; public: CTest(): INum ( 0 ) {} int. QScopedPointer guarantees that the object pointed to will get deleted when the current scope disappears. There are not so much Qt examples and demos with QSharedPointer because of the general concept for memory management in Qt using parent–child hierarchy of QObject. That's what's meant with "object is null" isNull() and operator!() are equivalent, you can use either one. These are the top rated real world C++ (Cpp) examples of QSharedPointer::getEndPoint extracted from open source projects. This is the type of the shared data object. QList<T> and QVarLengthArray<T> provide similar APIs and functionality. In that case, I think we should pass by reference. Qt also provides QSharedPointer, an implementation of a reference-counted shared pointer object, which can be used to maintain a collection of references to an individual pointer. I suspect the reason why T* operator doesn't exist is because there's the T* data() function which, like many of the other Qt classes such as QString, QByteArray etc. This blog post is the first in a series that will cover using OpenGL with Qt. > If you don't believe this matters, see comment in qdatetime. 209: The pointer to the object is kept here because it needs to match the actual: 210: deleter function's parameters, regardless of what template argument the: 211: last QSharedPointer instance had. QQueue inherits from QList. How can I register, for example, QSharedPointer< int > in meta type system. A more complex program sending QSharePointer objects using slots has a similar situation with GDB, that can be reproduced with the previous example. 0. out of scope, provided no other QSharedPointer objects are. [noexcept] const T *QSharedDataPointer:: constData const. Detailed Description. Good Morning everyone, I am using QSharedPointer with my classes derived from QObject. The QSharedPointer is an automatic, shared pointer in C++. C++ (Cpp) QSharedPointer Examples. In short - an atomic operation is one that is so "small" (hence the name) that it cannot be interrupted (for example by another thread) and therefore is thread-safe. QSharedPointer will delete the pointer it is holding when it goes. QWeakPointer objects can only be created by assignment from a QSharedPointer. Both serialization and desertialization are rather simple. C++ (Cpp) QSharedPointer::UpdateViewSection - 1 examples found. The requester class should also be in charge of managing the memory of the pointer it created. Copy assigns from other and returns a reference to this object. [/quote] There are not so much Qt examples and demos with QSharedPointer because of the general con. 24. A guarded pointer, QPointer<T>, behaves like a normal C++ pointer T *, except that it is automatically set to 0 when the referenced object is destroyed (unlike normal C++ pointers, which become "dangling pointers" in such cases). As reference the example tested on cross environment using GDB:I'm trying to store QSharedPointer<MyClass> values in a QVariant (so i can store it as custom data in a QComboBox) using: Qt Code: Switch view. 1. std::shared_ptr is a smart pointer that retains shared ownership of an object through a pointer. [quote author="situ117" date="1304279927"] I was reading about QSharedPointer in Qt. The QObjectList class is defined in the <QObject> header file as the following: typedefQList<QObject*>QObjectList; The first child added is the first object in the list and the last child added is the last object in the list, i. _pointer = QSharedPointer<APIRequest> (this);For example: @ QSharedPointer<QToolButton>(new QToolButton);@ I have been trying to make this work properly within a psuedo widget factory i have made( as the application has thousands of widgets) and I want to make sure that the memory is de-allocated properly. In many cases, that UB may be innocuous, but it is UB regardless. The QSharedPointer internals and the object are allocated in one single memory allocation, which could help reduce memory fragmentation in a long-running application. It just tracks whether or not it was deleted. It behaves exactly like a normal pointer for normal purposes, including respect for constness. If a new note is created, its reference is appended to the list: void Traymenu::newNote () { QSharedPointer<Note> note (new Note (this)); m_noteList << note; } For each Note-element, whichs pointers are in m_noteList, I want to get its title and. That said, your stack trace is really strange:. All children of a deleted QObject are deleted as well. You can inherit this class when you need to create a QSharedPointer from any instance of a class; for instance, from within the object itself. List of all members, including inherited members; Public FunctionsA "null" QSharedPointer wraps a T* t where t equals 0/NULL/nullptr. h","contentType":"file. [noexcept] const T *QSharedDataPointer:: constData const. If the type is an enumeration, flags() contains QMetaType::IsEnumeration. A little example would be. Qt Code: Switch view. 1010. Maybe it is a proper thing to add some C++14-style wrapper for creating QObjects like this: @ namespace Qt. An invalid model index can be constructed. Scale the images. T. Before I use QSharedPointer, I am used to use forward declaration to declare my class instead of include its . It. You can't assign two pointers to each other, but you can explicitly transfer the ownership of. Qt Base (Core, Gui, Widgets, Network,. . In this video series we will cover Qt 6. Code that makes use of delete are candidates for QScopedPointer usage (and if not, possibly another type of smart pointer such as QSharedPointer). The QSharedPointer internals and the object are allocated in one single memory allocation, which could help reduce memory fragmentation in a long-running application. maturity); by now, standard-library shared pointers are by far the. to ensure that the pointers being compared are equal. The exception is pointers derived from QObject: in that. A shared pointer holds an instance to an object that manages its own lifetime and QObjects don't!Their. C++ (Cpp) QSharedPointer::isNull - 30 examples found. In my project I create QObject instances and give them a parent-child relationship. Add a comment. QSharedDataPointer is a nifty way to implement copy-on-write and detaches/copies its object when it is accessed in a non-const way. This is a working example showing it calls. QSharedPointer:: objectCast() works reliably across DLL boundaries, but QSharedPointer:: dynamicCast() and std::dynamic_pointer_cast() don’t. For some reason, there are very few examples out there on how to use QSharedPointer, so i find myself posting here. com: 30. For. But, it all depends on your use case. // Create a fresh shared pointer in the scope QSharedPointer<uint8_t> image(new uint8_t[IMG_SIZE]); // the ring buffer can possibly be rewritten on the next usb_read() (if bufferlength = 1) so I copy. If you need a QSharedPointer, don't set the parent. As a iOS developer, I use a kind of smart pointers with reference counting implemented in NSObject whereby Im able to retain and release pointers when needed. 209: The pointer to the object is kept here because it needs to match the actual: 210: deleter function's parameters, regardless of what template argument the: 211: last QSharedPointer instance had. There is suspicious argument this in the Team constructor that looks like a pointer to. Smart pointers facilitate the dynamic memory operations. [/quote] Correct. 4. Before drawing you would create a local QSharedPointer<MyClass> in the drawing function and check if it is valid. But indeed Qt is leaking the functor object. To avoid passing raw pointers around I have changed all occurrences of DataProvider * to QSharedPointer<DataProvider>. So a conclusion would be: watch out for run-away. To complicate it even more, all debugging traces were leading to. The interface: Model. C++ (Cpp) QSharedPointer::getReferencedBlockId - 4 examples found. That means they should have a default constructor, a copy constructor, and an assignment operator. AnotherObject * something; The c++ (cpp) qsharedpointer example is extracted from the most popular open source projects, you can refer to the following example for usage. . If you want to actually delete a mutex, you have to remove it from the mutexes mapping. Some operators are missing by design, for example the assignment operator: QScopedPointer<int> i(new int(42)); i = new int(43); // will not compile i. The QSharedPointer is an automatic, shared pointer in C++. – Igor Tandetnik. Share. If this function can determine that the pointer has already been deleted, it returns nullptr . [quote author="koahnig" date="1309429658"] Well, if you are not careful enough, the run-away container may get you ultimately. The example below illustrates that it works in both single- and multi-threaded cases, and then reproduces. What is the point of emitting a QSharedPointer? The worker thread reads the files computes the data allocates and fills the memory with data, wraps it in QSharedPointer and passes it to the mainThread, which is used for plotting. #include <QWidget> #include <QSpinBox> class MyWidget : QWidget // A template widget to be placed in MainWindow { Q_OBJECT public: MyWidget () { this->spinBox = new. QScopedPointer has its copy constructor and assignment operator disabled. A question on using QSharedPointer with QImages. Several GBs of memory are en vogue today, but ultimately you can drain any big pond (as long as you do not call it ocean) ;-) [/. other. QSharedPointer will delete the pointer it is holding when it goes out of scope, provided no other QSharedPointer objects are referencing it. You can rate examples to help us improve the quality of examples. A more complex program sending QSharePointer objects using slots has a similar situation with GDB, that can be reproduced with the previous example. However, since, in this example, the reference count is exactly 1, it doesn't make a difference. qRegisterMetaType< QSharedPointer<TestClass> >("SharedTestClass"); in main() not as a global variable. QQuickItemGragResult *result = new. keyToAscii (key). QList<T> is one of Qt's generic container classes. Examples at hotexamples. It has all the features you may want in a modern pointer class: it is polymorphic, it supports static, const, and dynamic casts, it implements atomic reference-counting and thread-safe semantics, it supports custom. A guarded pointer, QPointer<T>, behaves like a normal C++ pointer T *, except that it is automatically set to 0 when the referenced object is destroyed (unlike normal C++ pointers, which become "dangling pointers" in such cases). So a conclusion would be: watch out for run-away. That said, your stack trace is really strange:. [/quote] That is a good example to be careful with smart pointers. GetInfo(9) GetRemoteId(8) AddChildren(5). If you look at the function definition, you'll see there is just one version : bool QMetaObject::invokeMethod ( QObject * obj, const char * member, QGenericArgument val0 = QGenericArgument ( 0 ), QGenericArgument val1 = QGenericArgument (), QGenericArgument val2 = QGenericArgument (),. The contents of the object pointed to by the pointer should not considered shared, however: there is. Qt로 프로그래밍할 때 메모리 관리 문제 (메모리 관리 불량으로 인한 메모리 누수 및 버그. no known conversion for argument 1 from 'const RecordPtr {aka const QSharedPointer<MyApp::Record>}' to 'const QObject*' you are trying to pass an object of type RecordPtr to a method expecting "const QObject*". Also, this Q_DECLARE_METATYPE(SharedTestClass) shouldn't be needed. This is the same as vector. QCborMap::Iterator class provides an STL-style non-const iterator for QCborMap. Just a small addition. Smart pointers facilitate the dynamic memory operations. See QWeakPointer::toStrongRef() for an example. Modifying the data in the container will then affect all curves that share the container. Then, a new QSharedPointer object is created that references the same int object. Thanks for any suggestion and comment, JulioHere's an example: void removeData() { QSharedPointer<DataPoints> dataPoint01(qobject_cast<DataPoints*>(sender())); // QList<QSharedPointer<DataPoints>> dataList; dataList. C++ (Cpp) QSharedPointer::Count - 2 examples found. But I've not seen it much in use in source code of Examples and Demos. See QWeakPointer::toStrongRef() for an example. [quote author="situ117" date="1304279927"] I was reading about QSharedPointer in Qt. QSharedPointer < T > QEnableSharedFromThis:: sharedFromThis If this (that is, the subclass instance invoking this method) is being managed by a QSharedPointer, returns a shared pointer instance pointing to this; otherwise returns a null QSharedPointer. As long as there is at least one QSharedPointer pointing to an object, the object is kept around. These conversions are called in a shared object which is properly loaded at runtime. You can use this constructor with any QObject, even if they were not created with QSharedPointer. These are the top rated real world C++ (Cpp) examples of QSharedPointer::UpdateViewSection extracted from open source projects. The problem is, that when implementing a QSharedAbstractItemModel, like the QAbstractListModel, you need to deal with raw pointers. To have that guarantee, use toStrongRef(), which returns a QSharedPointer object. It behaves exactly like a normal pointer for normal purposes, including respect for constness. This function was introduced in Qt 5.