[Development] Q_DECLARE_TYPEINFO and namespaced Qt
marc.mutz at kdab.com
Tue Jul 10 18:37:20 CEST 2012
as seen on IRC:
[18:18:43] <ossi|tt> thiago: how about we make Q_DECLARE_TYPEINFO automatically
use the qt namespace, like Q_DECLARE_METATYPE does? it is massively SIC, except
that probably not many outside qt/creator use it ...
[18:20:09] <marc_kdab_> ossi|tt: errhm, I used it in many projects, and the
Q_DECLARE_METATYPE solution is also not the best one
[18:20:22] <marc_kdab_> though I'm all for consistency, too
[18:20:34] <ossi|tt> marc_kdab_: but you probably didn't use qt in namespace?
[18:21:08] <marc_kdab_> could someone with VS 2005 and/or 2008 please test-drive
[18:21:42] <marc_kdab_> ossi|tt: I made KDTools work with a namespaced Qt, and hit
the problem of Q_DECLARE_TYPEINFO there
[18:22:23] <ossi|tt> marc_kdab_: yeah. i'd instantly change it. not sure about the amount
of opposition to expect, though
[18:22:50] <marc_kdab_> ossi|tt: the question is: change which way?
[18:23:26] <ossi|tt> marc_kdab_: have it in the namespace transparently. it's insane that
user code needs to be aware of this in this context
[18:24:21] <marc_kdab_> ossi|tt: but user code needs to be aware of a namespaced Qt
in any case. Wrapping the QClass forward-declarations was the most work, and then
wrapping Q_DECLARE_TYPEINFO, too, is just consistent
[18:24:47] <marc_kdab_> (wrapping in QT_BEGIN_NAMESPACE /
QT_END_NAMESPACE, that is)
[18:25:06] <ossi|tt> marc_kdab_: yes, but it's stupid that i need to wrap a macro with
another macro pair
[18:26:12] <marc_kdab_> ossi|tt: depends how your take is on consistency, I guess
[18:27:42] <marc_kdab_> I don't have an opinion myself; both ways have pros and cons...
[18:27:59] <marc_kdab_> if in doubt, stay with the status quo, I guess
[18:28:06] <ossi|tt> marc_kdab_: this macro is clearly optimized for the use in qt, where
everything is wrapped in these macros anyway
[18:28:35] <ossi|tt> marc_kdab_: the easiest way out would be
As I said, I'm undecided. On one hand, I always have to look at the implementation to see
whether I need to wrap the macro in QT_BEGIN_NAMESPACE /
QT_END_NAMESPACE, and I would like to see consistency here, on the other hand, in a
way it's Q_DECLARE_METATYPE that's inconsistent, since it violates the "put Qt stuff
into QT_BEGIN_NAMESPACE if you want to be compatible with a namespaced Qt,
otherwise don't bother" assumption.
What's the general opinion on this?
Marc (& Ossi)
Marc Mutz <marc.mutz at kdab.com> | Senior Software Engineer
KDAB (Deutschland) GmbH & Co.KG, a KDAB Group Company
www.kdab.com || Germany +49-30-521325470 || Sweden (HQ) +46-563-540090
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