Shared Object class between multiple Widgets

[vladozar]

HI

I'm trying to creat an Object that will contains some data and that will be avaliable to multiple Widgets. Also, if one Widget changes some data in the Object, next time some other Widget reads the data from Object, it will have the new chaged data.

For example.

Lets say we have

QWidget widgetA
QWidget widgetB
// more QWidgets are in my program, but for example purpose, we will use two widgets
// Both widgets are sepereate dialogs, widgets, mainWindows and have theier own classes and  *.h and *.cpp files
 
// And some QObject that also has its own class and and  *.h and *.cpp file
QObject sharedData
// And in the sharedData, lets say we have some public items (declared in the header file):
QString string
QString stringTwo
int number

QWidget widgetA
QWidget widgetB
// more QWidgets are in my program, but for example purpose, we will use two widgets
// Both widgets are sepereate dialogs, widgets, mainWindows and have theier own classes and  *.h and *.cpp files

// And some QObject that also has its own class and and  *.h and *.cpp file
QObject sharedData
// And in the sharedData, lets say we have some public items (declared in the header file):
QString string
QString stringTwo
int number

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What I wnat to do, is when widgetA changes some part of the sharedData Object,

// in the widgetA, some sharedData items are chaged like
sharedData->string = "apple";
sharedData->num = 10;

// in the widgetA, some sharedData items are chaged like
sharedData->string = "apple";
sharedData->num = 10;

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I need to be able that widgetB would read the changes made by widgetA

// lets say
qDebug()<<sharedData->string;
//will return "apple" and not an emtpy string

// lets say
qDebug()<<sharedData->string;
//will return "apple" and not an emtpy string

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My question is how do i set up my object and how do I implament this object withing widgets. I know, I have to use pointers, but I have problem in initial setup.

Thanks to all. Hope to here from some one.

[Lykurg]

If you can't handle pointer (or it gets to complicated) you can use the singleton approach. (See our wiki)

[lni]

Use QExplicitlySharedDataPointer and QSharedData

[vladozar]

Use QExplicitlySharedDataPointer and QSharedData

Thanks for the answer, but I have read this pages, but still have trouble figuring out how to actually use it. It is still unclear to me how to actuall implament it. Is it possible to get an actuall working example of how this works? Are there any demos or example of it?
thanks

[wysota]

Why don't you just pass a pointer to the object to all those widgets as already suggested?

[vladozar]

my question is how to pass it? any code examples?

[wysota]

class X {
public:
   void setData(Data *ptr) {
      m_data = ptr;
   }
private:
    Data *m_data;
};

class X {
public:
   void setData(Data *ptr) {
      m_data = ptr;
   }
private:
    Data *m_data;
};

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Or use the singleton pattern as already advised.

[MarekR22]

I don't understand problem?
Why you don't just use signal slot mechanism?
setters as a slots and somthingChanged signals should do the trick.
You have some QObject storing all shared values with setters getters and change signals and just connecting appropriative signa-slots between this object and other widgets.
Data sharing is not needed!
Standard pattern of setter with change signal:

void CommonDataQObject::setSomeString(const QString &a) {
     if (this->mSomestring!=a) {
         this->mSomestring=a;
         emit someStringChaned(a); // emit signal which should be connected to other widgets
     }
}

void CommonDataQObject::setSomeString(const QString &a) {
     if (this->mSomestring!=a) {
         this->mSomestring=a;
         emit someStringChaned(a); // emit signal which should be connected to other widgets
     }
}

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[wysota]

The problem is lack of C++ skills.

[kito]

i think you need to start with OOP.That can solve your problem