[Qt-interest] how to pass the reference to QMap to other class

[franki]

Hi all,

I have one class where i have QMap which has some data, I want to be able to 
easly access this data in second class, so what I want is to pass this QMap 
from first class to second class as a reference (without copying data). 
I googled and I've done it like this (snippet of code):

first class header :
public:
	FirstClass(QObject *parent)
	QMap<int,DataStruct>	myMap;
public slot:
	QMap<int,DataStruct>& getMap();

first class body:
	QMap<int,DataStruct>& FirstClass::getMap() {
    		return myMap;
	}

second class header:
public:
    SecondClass(Ui::MainPages m,FirstClass *firstClass);
private:
    Ui::MainPages   mp;
    FirstClass      *firstClass;
    QMap<int,DataStruct>&   myMap;

second class body:
SecondClass::SecondClass(Ui::MainPages m,FirstClas *firstClass): 				
                                      QWidget(),myMap(firstClass->getMap())
{
    mp=m;
    this->firstClass=firstClass;
}

So the problem is wierd, when I change data of the item in QMap in firstClass 
I can see the change in secondClass by accessing private variable myMap,
but when I add new member to QMap in firstClass I can't see this new member in 
secondClass by using private variable myMap, although I can access this new 
member when I'm using pointer to first class like this:
firstClass->myMap

What is wrong with this, and how should I do that properly?
I'm aware that in second class I can access QMap by pointer to first class:
firstClass->myMap 
but I wanted to have reference to myMap in second class without using pointer 
to first class.

please advise me.

best regards
Marek
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