How to send variables between classes in Qt

How to send variables between classes in Qt

Date : October 23 2020, 06:10 PM
it helps some times Use signals/slots mechanism to share values between two QObject.
For example:
code :
class Widget1: public QWidget
    Widget1(): QWidget(),
        message(new QLineEdit())
        QPushButton* button = new QPushButton("Send msg", this);
        connect(button, &QPushButton::clicked, this, [=]() { emit this->sendMsg(message->text());}); // When you click on the button, it will emit the signal sendMsg

        QVBoxLayout* layout = new QVBoxLayout(this);
    QLineEdit* message;
    void sendMsg(QString const& msg);
class Widget2: public QWidget
    Widget2(): QWidget(),
        display(new QLabel("Nothing to display", this))
        QVBoxLayout* layout = new QVBoxLayout(this);
    QLabel* display;
public slots:
    void receive(QString const& message)
        display->setText(message); // When called, display the message in the label
int main(int argc, char *argv[])
    QApplication app(argc, argv);

    QWidget* mainWidget = new QWidget();
    QHBoxLayout* layout = new QHBoxLayout(mainWidget);

    Widget1* w1 = new Widget1();
    Widget2* w2 = new Widget2();

    // When the signal sendMsg is emitted, call the slot receive
    QObject::connect(w1, &Widget1::sendMsg, w2, &Widget2::receive);

    return app.exec();

Share : facebook icon twitter icon
Extending static classes in PHP - Avoiding sharing variables for multiple classes in extended class

Extending static classes in PHP - Avoiding sharing variables for multiple classes in extended class

By : Chris
Date : March 29 2020, 07:55 AM
I hope this helps . Since $className is static and within the parent class, when you set className within A or B, it changes the variable within the parent, and the same is done when the variable is read. Unless you override className in your extended classes, you'll be storing and retrieving information from the same memory location, originally defined in InstanceModule.
If you redefine className in A/B, you can access className using parent:: or self:: from InstanceModule or A/B respectively. Depending on what you are trying to do, Abstract classes may also play a significant role.
F# constructors and classes: Set up classes without extra mutable variables for each member property

F# constructors and classes: Set up classes without extra mutable variables for each member property

By : Ruby
Date : March 29 2020, 07:55 AM
Hope this helps So I have been looking at this page on the MSDN about constructors in F#. I am looking at the very first code sample , You can use this syntax
code :
type MyClass(property1 : int) =
    member val Property1 = property1
    member val Property2 = "" with get, set
Python: classes handling mutable variables in inherited classes which depend on parent class

Python: classes handling mutable variables in inherited classes which depend on parent class

By : Afzal Ali
Date : March 29 2020, 07:55 AM
wish help you to fix your issue You could use properties to accomplish this. You can then override the necessary properties in the child classes to achieve your desired result. For example:
code :
class CommonParent(object):

    def format_field(self):
        return u'parent_format'

    def mutable_field(self):
        return u'parent_replace'

    def result_string(self):
        return '{0} {1}'.format(self.mutable_field, self.format_field)

class Child1(CommonParent):
    def mutable_field(self):
        return u'child1_replace'

class Child2(CommonParent):
    def format_field(self):
        return u'child2_format'

    def mutable_field(self):
        return u'child2_replace'

class Result1(Child1):

class Result2(Child2):

if __name__ == '__main__':
    r1 = Result1()
    print(getattr(r1, 'result_string'))

    r2 = Result2()
    print(getattr(r2, 'result_string'))
child1_replace parent_format
child2_replace child2_format
Do classes not inherit static variables from the classes they extend?

Do classes not inherit static variables from the classes they extend?

By : Mahmoud Ziada
Date : March 29 2020, 07:55 AM
To fix the issue you can do That's correct. Static variables are not inherited by subclasses. This is documented here, which also suggests working around it by declaring an instance variable with the same name. Not sure how useful of a workaround that is, since you might as well change the static variable to an instance one instead of having both (unless you really need to call Animal.debug elsewhere), but it's AS3, it's there.
Send variables to other classes

Send variables to other classes

By : Eric James P Belleca
Date : March 29 2020, 07:55 AM
With these it helps Don't reinvent wheels, use the DateTime.TryParseExact method which is built specifically for this purpose. Forget about regexes and substrings when you are dealing with dates in the .NET framework:
Related Posts Related Posts :
  • Compiler error when overriding virtual methods
  • What is the point of function pointers?
  • Which is faster in memory, ints or chars? And file-mapping or chunk reading?
  • ISO file in C++
  • Expected Class-name before { token
  • Can I trust floats or doubles representing integers to retain precision?
  • Qt execute multiple get with QNetworkAccessManager
  • Big and Little endian question
  • Visual Studio 2008 compiles anything in C++ file?
  • C++ pointer to functions, Beginner Question
  • Fastest algorithm for primality test
  • Passing array of pointers to another class
  • Handling macro redefinition without modifying .h files ... C / C++ language
  • Implement SSL with SSPI: How to start?
  • Creating a simple VS2008 visualizer inside autoexp.dat (problem with casting)
  • C++ - Unicode Newline
  • Program crashing with 'std::out_of_range' error
  • Use signed or unsigned char in constructing CString?
  • Parallel execution policies in C++ 17
  • C++ Class Templates (Queue of a class)
  • Convert image into useable byte array in C?
  • pointer to preallocated memory as an input parameter and have the function fill it
  • Animated Image in Win32
  • error on compiling statically linked library created in Qt
  • How to easily pass a very long string to a worker process under Windows?
  • Can a class add friend classes at runtime in C++?
  • C++ priority queue in ascending order by specific method for objects
  • Initialize and declare dynamically multiple variables of random entities in a loop in C++
  • Serializing, integer without libaries , getting weird results
  • Function pointers with default parameters in C++
  • Compilation errors with RapidXML
  • Bad_alloc exception when using new for a struct c++
  • count specific things within a code in c++
  • How to extract 48*48 icon image from resource of an executable file?
  • C++ Convert string (or char*) to wstring (or wchar_t*)
  • C++ include .h includes .cpp with same name as well?
  • Any way in C++ to forward declare a function prototype?
  • boost graph adjacency_list, retrieving a node's parents
  • Copy method optimization in compilers
  • what the problem in this program? it doesn't use the second number, and doesn't print the last line?
  • Need to format character precedence in Strings
  • Cross-Platform Camera API
  • sizeof continues to return 4 instead of actual size
  • String search algorithm used by string::find() c++
  • Two-phase lookup: can I avoid "code bloat"?
  • Strongest cipher available to use with C/C++?
  • Why does my program occasionally segfault when out of memory rather than throwing std::bad_alloc?
  • Firefox XULRunner or TriXul?
  • Does GetSystemInfo (on Windows) always return the number of logical processors?
  • Where is the difference between these code? Shouldn't output be the same?
  • What does it mean mean by "Expected a statement" in C++
  • keybd_event is not working right =(
  • What native C++ profiling tool do you suggest?
  • how to copy char * into a string and vice-versa
  • C++ write to front of file
  • Delphi conversion of C++ header for DVP7010B video card DLL?
  • I keep Getting Control reaches end of non-void function. What am I doing wrong?
  • How to have struct members accessible in different ways
  • Am I abusing Policies?
  • Modern equivalent of BoundsChecker for Visual Studio 2008
  • shadow
    Privacy Policy - Terms - Contact Us © 35dp-dentalpractice.co.uk