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Thread: how couild one simplify calling of same methods for different inherited classes.

  1. #1
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    Default how couild one simplify calling of same methods for different inherited classes.

    in my code using several qt widget classes I ses code like this:

    } else if (caMenu *widget = qobject_cast<caMenu *>(w)) {
    //qDebug() << "we have a menu";

    if(data.edata.connected) {
    // set no connection color
    } else {
    widget->setAlarmColors(NOTCONNECTED);
    widget->setProperty("Connect", false);
    }
    widget->setAccessW(data.edata.accessW);

    // choice ================================================== ================================================== ==============
    } else if (caChoice *widget = qobject_cast<caChoice *>(w)) {
    //qDebug() << "we have a choiceButton" << String << value;

    if(data.edata.connected) {
    // set no connection color
    } else {
    widget->setAlarmColors(NOTCONNECTED);
    widget->setProperty("Connect", false);
    }
    widget->setAccessW(data.edata.accessW);

    } else if .....



    ===============================
    how could one call a routine using the same code with the same methods after dynamic casting ?

  2. #2
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    Default Re: how couild one simplify calling of same methods for different inherited classes.

    You got it worng..
    how couild one simplify calling of same methods for different inherited classes.
    They not not same methods, they are two different methods each operating on a different TYPE (caMenu and caChoice). The thing common between them is they use the same logic / algorithm / techinique...

    What you have is a compact form possible. The other way I can think of is have a template function somthing like
    Qt Code:
    1. template <typename T>
    2. bool isMyType<T>(QObject * object)
    3. {
    4. T * obj = qobject_cast<T *>(object);
    5. return obj != 0;
    6. }
    To copy to clipboard, switch view to plain text mode 
    When you know how to do it then you may do it wrong.
    When you don't know how to do it then it is not that you may do it wrong but you may not do it right.

  3. #3
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    Default Re: how couild one simplify calling of same methods for different inherited classes.

    you are right, my phrasing was not correct. However I meant it your way.

    How would you use the templating then in my example?

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    Default Re: how couild one simplify calling of same methods for different inherited classes.

    Qt Code:
    1. if(isMyType<caMenu *>(w))
    2. qDebug() << "we have a menu";
    3. ...
    4. if(isMyType<caChoice *>(w))
    5. qDebug() << "we have a choiceButton" << String << value;
    6. ...
    To copy to clipboard, switch view to plain text mode 
    When you know how to do it then you may do it wrong.
    When you don't know how to do it then it is not that you may do it wrong but you may not do it right.

  5. #5
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    Default Re: how couild one simplify calling of same methods for different inherited classes.

    yes I understand the way you can test the type of the widget. However I do not see how I can then call the methods (widget->SetPropoerty) correctly casted and how the code is then simplified.

    many thanks for your answers.

  6. #6
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    Default Re: how couild one simplify calling of same methods for different inherited classes.

    setAlarmColors
    setProperty
    setAccessW

    what is the highest common class that has all of those methods? Lets say it is ClassX. If there isn't a common clsss then you should make an interface that does contain all the methods, then make all relevant classes inherit the interface (e.g. InterfaceX)
    Then you just need one check:

    Qt Code:
    1. if (ClassX *widget = qobject_cast<ClassX*>(w)) { // or InterfaceX
    2. //qDebug() << "we have a ... not sure exactly what it is, but we know it has all the methods required...
    3.  
    4. if(data.edata.connected) {
    5. // set no connection color
    6. } else {
    7. widget->setAlarmColors(NOTCONNECTED);
    8. widget->setProperty("Connect", false);
    9. }
    10. widget->setAccessW(data.edata.accessW);
    To copy to clipboard, switch view to plain text mode 
    If you have a problem, CUT and PASTE your code. Do not retype or simplify it. Give a COMPLETE and COMPILABLE example of your problem. Otherwise we are all guessing the problem from a fabrication where relevant details are often missing.

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