best way to extend QVariant to support std::string?

[TorAn]

I found out that I need to extend support of std::string in QVariant. Specifically, to allow std::string as an argument in constructor.
Other then deriving from QVariant, (something like myQVariant : public QVariant) and supplying the signatures for all datatypes that are relevant for me, including std::string - may be there is another way? I am not considering the option of chaging Qt sources.

Thanks

[MarekR22]

1. declare meta type in some header file: Q_DECLARE_METATYPE
2. just after QApplication is created register new type using: qRegisterMetaType
3. Now you can use QVaiant with almost any type (requirements are listed in Q_DECLARE_METATYPE documentation).

[ChrisW67]

QVariant is designed to be extended using the mechanisms MarekR22 outlines above. You can then use the named constructor QVariant::fromValue() or QVariant::setValue()

#include <QtCore>
#include <iostream>
 
Q_DECLARE_METATYPE(std::string)
 
int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
 
    qRegisterMetaType<std::string>("std::string");
 
    std::string s("Test");
    QVariant v1( QVariant::fromValue<std::string>(s) );
    QVariant v2;
    v2.setValue(s);
 
    std::string t1 = v1.value<std::string>();
    std::cout << t1 << std::endl;
    std::string t2 = v2.value<std::string>();
    std::cout << t2 << std::endl;
 
    return app.exec();
}

#include <QtCore>
#include <iostream>

Q_DECLARE_METATYPE(std::string)

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
    
    qRegisterMetaType<std::string>("std::string");

    std::string s("Test");
    QVariant v1( QVariant::fromValue<std::string>(s) );
    QVariant v2;
    v2.setValue(s);

    std::string t1 = v1.value<std::string>();
    std::cout << t1 << std::endl;
    std::string t2 = v2.value<std::string>();
    std::cout << t2 << std::endl;

    return app.exec();
}

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