Explain Qt build class details or ponit and correct my errors .

Anonymous_Banned275

OK, I am going to abuse the purpose of this subforum - to discuss
anything C++_ land related.

I need somebody to explain in English highlighted text in this post,
and please do not laugh or tell RTFM.
Opinions not related to subject....

#ifndef A_TEST_CLASS_H
#define A_TEST_CLASS_H

#include <QObject>

class A_TEST_Class : public QObject  
**class A_TEST  inherits from (base class )  QObject   true or false ?**

{
    Q_OBJECT  **what is the term for this here and why is it here ?**
                          **base class has been specified already why this ?**
public:
    explicit A_TEST_Class(QObject *parent = nullptr);
**is there a reason using  non ISO standard "parent " term here ?
and  give an example when "parent" would not be  default null** 
**if it is null why is it there - is it not used then ?** 
signals:

};

#endif // A_TEST_CLASS_H

class definition ( correct term ?)
OK, non ISO standard term "parent" is used again - fine

#include "a_test_class.h"
**bellow is an  explicit constructor  for purpose of passing parameters to class** 
 
A_TEST_Class::A_TEST_Class(**QObject *parent**)

**what is the purpose of this and what is it call ?**
**it is NOT "passing parameter to constrictor " or is it ?** 


    : QObject{parent}
QObject with default parent = nullptr is passed as class parameter correct ?
so we have class derived from QObject 
and a QObject passed as a parameter too ?
**is it a duplicate ?** 
{

}

Please accept my apology for posting such basic stuff, but I am getting frustrated with non-standard terminology and "automatically generated " stuff by Qt which lacks explanations because of few "experts" here cannot be bothered and often pass RTFM instead.

Cheers

Christian Ehrlicher

@AnneRanch said in Explain Qt build class details or ponit and correct my errors .:

class A_TEST inherits from (base class ) QObject true or false ?

Correct

{
Q_OBJECT what is the term for this here and why is it here ?
base class has been specified already why this ?

It's needed for Qt meta object system: https://doc.qt.io/qt-6/qobject.html#Q_OBJECT

public:
explicit A_TEST_Class(QObject *parent = nullptr);
**is there a reason using non ISO standard "parent " term here ?

'parent' is just a name of a paramenter, don't know why this has to be iso-certified.

and give an example when "parent" would not be default null**
if it is null why is it there - is it not used then ?

This is properly explained here: https://doc.qt.io/qt-6/objecttrees.html

is it a duplicate ?

No - once you derive from a QObject, the other one just passes a parameter of type QObject.

non-standard terminology

What exactly is non-standard - 'parent' - it's a parameter name and you should know what a 'parent' is.

"automatically generated " stuff by Qt which lacks explanations

Qt does automatically generated meta-object stuff explained in my links above and here: https://doc.qt.io/qt-6/moc.html
The ui to header generation is explained here: https://doc.qt.io/qt-6/designer-using-a-ui-file.html

So please tell us exactly what is non-standard or not documented properly here.

Anonymous_Banned275

@Christian-Ehrlicher OK, your reply is pretty much following C++ inheritance , from base class ( QObject) to derived class.
Very simple instance would be
QObject base class
QWidget derived class
I have no suggestion in renaming these insisted of parent and child -- so let it be.
The task I am trying to accomplish , and maybe it is futile , is to
iterate "backwards " starting with derived class "up " to the base class.

I have no issues iterating "frontwards" - from base class to derived class.
I have been looking at QTree derived classes and have not found them applicable for my task. .

My inheritance layout is "multilevel " and I may have to figure out a way to iterate from base to derived classes and start "normal" from base .
The problem is my derived classes are dynamic - instantiated as needed.

In simle term - why I cannot iterate from derived class to base class?

Christian Ehrlicher

@AnneRanch said in Explain Qt build class details or ponit and correct my errors .:

I have no suggestion in renaming these insisted of parent and child -- so let it be.

Nobody named the inheritance of classes as 'parent and child' - you just mix this up yourself. These are two different things but you refuse to understand this for unknown reasons...

Inheriting: A derives from B (QMainWindow derives from QWidget derives from QObject) - a QMainWindow is a QObject.

Parent - Child relationship (a.k.a Composition): A has a member (direct or indirect) of B - a QMainWindow has a central QWidget (which itself can be anything derived from QWidget).
These are basic c++ concepts which you constantly mix up and blame others for it.

In simle term - why I cannot iterate from derived class to base class?

I don't know what you want here - do you mean casting?

Anonymous_Banned275

To whom it MAY concern :
since this “discussion” is turning into mindless , robotic, and repetitive references to RTFM
AND so far has not provided solution to the issue ,
I am requesting the entire discussion to be scrapped , PERMANENTLY deleted from this forum.
It serves no porpoise to keep it as “unsolved” , it just occupies valuable space as such
It is of no public benefits to keep as “unsolved”.
PLEASE
REMOVE, DELETE PERMANENTLY ASAP.
Thank you for your support.

Christian Ehrlicher

I'm sorry that you have to read documentation if you want to learn something. Especially something such basic c++ stuff.