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Finding Classes By Meta Information



  • Having registered several class types using the qRegisterMetaType function, is there any way I'm able to iterate through these registered classes and check for specific type inheritance?

    I want to build a list of specific classes which derive from a certain base class and then add these into a QListWidget.

    Not sure even where to begin.


  • Qt Champions 2017

    @webzoid said in Finding Classes By Meta Information:

    is there any way I'm able to iterate through these registered classes

    I don't believe so, you should keep that information yourself.

    check for specific type inheritance?

    You can do that. Suppose you have a class X that's registered as a metatype, and you want to check if it's derived from a class Y (also registered as a metatype). Then you can pull the meta-object for that class and check it against the one for class Y. Something along those lines (Qt 5.7+):

    const QMetaObject * xMetaObject = QMetaType::metaObjectForType(qMetaTypeId<X>());
    const QMetaObject * yMetaObject = QMetaType::metaObjectForType(qMetaTypeId<Y>());
    Q_ASSERT(xMetaObject && yMetaObject);
    
    if (xMetaObject->inherits(yMetaObject))
        ; // X is derived from Y;
    else
        ; // ... it is not
    


  • @kshegunov Thank you for your comprehensive response.

    The last bit is very useful but its a shame that I can't iterate through registered meta types. I s'pose I could always have my own function which registers the type into a list (maintaining the MetaTypeId for instance as well as calling qRegisterMetaType.


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