On 05-11-2025 09:10, Arno Rehn wrote:
On 05.11.2025 08:22, Daniel Schürmann wrote:
However I am not confident that this bullet proved enough for being
integrated in the upstream library.
* It works by guessing the parent argument which can fail at runtime
without even a compiler message, in users code.
* It does not yet (<x++23) support constructors requiring a sub
class parent like QWidget or any other user defined sub class.
* We can make it more robust by constructing without parent and then
call setParent() causing some extra calls and bookkeeping. I
don't want that.
Honestly I think you're over-engineering this somewhat. "parent comes
last" is an established convention when dealing with QObject-derived
classes. QWidgets are the same, see for example QPushButton:
QPushButton(const QIcon &icon, const QString &text, QWidget *parent)
Just forward the args and append "this" as the last parameter to pass
the parent along.
Problem is, I guess, that while it is a convention, it is not true 100%
of the time. Not even in Qt. See QWidget for instance as a counterexample:
[explicit] QWidget::QWidget(QWidget *parent = nullptr,
Qt::WindowFlags f = Qt::WindowFlags())
For customer code, you can't be sure people followed this convention at
all of course.
Re subclass parents: You don't actually need C++23 for that. We can
(ab-)use a templated implicit conversion operator to auto-cast a type
to the one required by the constructor:
Wow... that looks... dirty. My kind of dirty trick.
Cheers,
André
--
Development mailing list
[email protected]
https://lists.qt-project.org/listinfo/development
