Use "extern QStandardItemModel*" to provide access from anywhere?

[squidge]

I'd go for more of a container solution. Rather than having the customers, articles, invoices, etc polluting the global namespace, create a management class for them and then pass a reference to this management class in the constructor of your other classes so they may use it to access the data they need.

I certainly wouldn't use global variables for the task. You start with a single global, and then it multiplies, and then before you know it you have code that isn't maintainable or reusable easily in other projects (you have to have knowledge of the application as a whole, rather than just specific classes)

[homerun4711]

Thanks for the anwers. I think I go for that container solution.

Is there some example code around for dealing with models in that way?

[squidge]

Something like: [pseudo code]

class DataManager
{
public:
DataManager(); // Remember to set m_customerModel etc to NULL in constructor
~DataManager();
void SetCustomerModel(QStandardItemModel *customerModel);
void SetInvoiceModel(QStandardItemModel *invoiceModel);
#ifdef DEBUG
QStandardItemModel *customerModel()
{
if (m_customerModel == NULL) throw E_NULLPOINTEREXCEPTION;
return m_customerModel;
}
#else
inline QStandardItemModel *customerModel() {return m_customerModel};
inline QStandardItemModel *invoiceModel() {return m_invoiceModel};
#endif
private:
QStandardItemModel *m_customerModel;
QStandardItemModel *m_invoiceModel;
};
 
DataManager *dmgr = new DataManager();
dmgr->SetCustomerModel (myModel);
[...]
myNewClass = new someclass(dmgr);
[...]
dmgr->customerModel()->doSomething(); or pass dmgr->customerModel() pointer to some other function or class. 
If you added another pointer to the class and forget to call the set(), it'll just throw an exception to remind you.

class DataManager
{
public:
DataManager(); // Remember to set m_customerModel etc to NULL in constructor
~DataManager();
void SetCustomerModel(QStandardItemModel *customerModel);
void SetInvoiceModel(QStandardItemModel *invoiceModel);
#ifdef DEBUG
QStandardItemModel *customerModel()
{
if (m_customerModel == NULL) throw E_NULLPOINTEREXCEPTION;
return m_customerModel;
}
#else
inline QStandardItemModel *customerModel() {return m_customerModel};
inline QStandardItemModel *invoiceModel() {return m_invoiceModel};
#endif
private:
QStandardItemModel *m_customerModel;
QStandardItemModel *m_invoiceModel;
};

DataManager *dmgr = new DataManager();
dmgr->SetCustomerModel (myModel);
[...]
myNewClass = new someclass(dmgr);
[...]
dmgr->customerModel()->doSomething(); or pass dmgr->customerModel() pointer to some other function or class. 
If you added another pointer to the class and forget to call the set(), it'll just throw an exception to remind you.

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[homerun4711]

Thank you very much. I already wrote some lines on this also called my class DataManager

Kind regards,
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