On Thu, 16 Oct 2025 at 17:32, André Somers via Development
<[email protected]> wrote:
> > > Perhaps it might be easier or better to add a make_child template method
> > to QObject that returns a new instance of the template type, parented to
> > the object you call it on?
> >
> > That's actually the solution I was looking for.
> > I love that idea. Thank you.
> >
> > What type is the returned pointer? I like to have one that has the
> > semantical guarantee of being a child object. This is beneficial to
> > distinguish classic owned pointer member variables from borrowed from
> > the Qt Object tree.
> >
> > Do you have an idea?
> Well, my suggestion would be to not introduce a separate non-owning
> pointer type at all, so it would just return the type itself, just like
> new does.
Precisely so. Our ostensible declaration (and definition) is
class QObject {
...
public:
template <class Child, class... Args>
Child* makeChildObject(Args&&... args)
{
return new Child(std::forward<Args>(args)..., this);
}
};
and that's all there is to it.
The reason it's a reach too far to return some
semantically-parented-pointer instead is adoptability.
With this approach, you can just change
MyType* var = new MyType(foo, bar, someParent);
to
MyType* var = someParent->makeChildObject<MyType>(foo, bar);
and there's no need for heavier refactorings in how that code uses
MyType*. It doesn't need to be refactored to
use a parented_ptr everywhere.
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