On 16.09.19 12:32, Ulf Hermann wrote:
> [...]
The place where all the metatypes are known at compile time is inside
moc.
Well, unfortunetely, even moc doesn't know about all the metatypes.
Many types don't need registration, and moc is not always aware of the
Q_DECLARE_METATYPE declaration (but it actually should still work for most types)
There are also all the custom QMetaObject (thinking of stuff like DBus,
ActiveQt or other language bindings, or the ones created by Verdigris)
Therefore I propose an additional parameter "--json" for moc that would
generate just such files, in JSON format, to be processed by further
tools.
Sounds like a good idea.
In addition, moc should also gain the ability to collect multiple
such per-C++-file JSON files into one per-module JSON file. The latter
is a pure JSON transformation and doesn't require any insight about the
actual types.
But this post-processing of the .json files is not necessarily something for
moc. It could be in a separate tool. (But I realize that you can just add the
option to the moc binary to avoid creating another small tool just for that.)
The proposed change to moc is
https://codereview.qt-project.org/c/qt/qtbase/+/248470 and a proposed
qmltyperegistrar which would use the metatype information to generate
plugins.qmltypes files at compile time can be seen at
https://codereview.qt-project.org/c/qt/qtdeclarative/+/248471 (mind the
dependency chain).
The question is also how does it fits in the build system? How do you know
which .json to collect and at what stage do you do that?
Is this going to add some burden for people using custom build systems?
And how mandatory will it be? Is it ok if this does not work?
Also I would need to find a solution for Verdigris. (Was thinking about
generating the json at compile time in a constexpr string put in a specific
section of the binary, but how does it ends up in a qmltypes then?)
--
Olivier
_______________________________________________
Development mailing list
Development@qt-project.org
https://lists.qt-project.org/listinfo/development
