[Qt-interest] When is QT_FORWARD_DECLARE_CLASS to be used?

[Scott Aron Bloom]

In the code... Its defined as the following
#ifndef QT_NAMESPACE
# define QT_FORWARD_DECLARE_CLASS(name) class name;
#else
# define QT_FORWARD_DECLARE_CLASS(name) \
    QT_BEGIN_NAMESPACE class name; QT_END_NAMESPACE \
    using QT_PREPEND_NAMESPACE(name);
#endif

So they qt developers created a shortcut for forward declaring a class
that would take care of the namespace optionally being there...

Honestly.. Ive never used the macro... but I don't think it would hurt,
especially if you plan on using the namespace...

BTW. its in qglobal.h

Scott

> -----Original Message-----
> From: qt-interest-bounces at trolltech.com [mailto:qt-interest-
> bounces at trolltech.com] On Behalf Of Tony Rietwyk
> Sent: Friday, April 17, 2009 10:26 PM
> To: qt-interest at trolltech.com
> Subject: [Qt-interest] When is QT_FORWARD_DECLARE_CLASS to be used?
> 
> Hi Everybody,
> 
> In 4.5.0, demos\books\bookdelegate.h has:
> 
> #ifndef BOOKDELEGATE_H
> #define BOOKDELEGATE_H
> 
> #include <QModelIndex>
> #include <QPixmap>
> #include <QSize>
> #include <QSqlRelationalDelegate>
> 
> QT_FORWARD_DECLARE_CLASS(QPainter)
> 
> class BookDelegate : public QSqlRelationalDelegate
> {
> public:
> 
> ... etc.
> 
> 
> Is QT_FORWARD_DECLARE_CLASS also required in our code?
> 
> It's not in the QtAssistant index, and searching only provides links
to demos.
> 
> Can someone provide the missing documentation.
> 
> Thanks,
> 
> Tony.
> 
> 
> 
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