Hi Simon, On Tue, Jan 26, 2016 at 06:49:11PM +0100, Simon McVittie wrote: > On 26/01/16 10:37, Dmitry Shachnev wrote: >> My point was that Qt main loop is usually used on Windows / OS X but *not* >> on Debian. Here, Qt is compiled with GLib support and will use GLib main >> loop unless explicitly asked not to do so (via QT_NO_GLIB=1 env variable). >> That is a very rare use case and I don't see why one will ever need it. > > Am I right in thinking that Qt programs always the same external-facing > main-loop API, and that results in callbacks being scheduled from GLib's > GMainContext on Debian under normal circumstances, or from Qt's built-in > equivalent of GMainContext/libevent/etc. on Windows, OS X, or with > QT_NO_GLIB?
Right. Applications always use QCoreApplication/QEventLoop, that creates an event dispatcher internally, which is different on different platforms. On other platforms it may also use platform-specific dispatchers, though it is not relevant for us. For UNIX the logic is at: https://code.woboq.org/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp.html#489 > dbus-python needs two things to work with a particular main-loop: it > needs to be told how to make that main-loop monitor libdbus connections > (a dbus.mainloop.* module), and the application author needs to actually > be iterating that main-loop. > > For GLib, dbus.mainloop.glib is bundled with dbus-python, but the > application author also needs to iterate the GLib main-loop via PyGI, > either directly or by using a higher-level API like Gtk or GApplication. > For Qt, dbus.mainloop.whatever replaces dbus.mainloop.glib (but on > Debian, dbus.mainloop.glib would also work), and QApplication replaces > PyGI (but on Debian, PyGI would also work). > > The "main loop" terminology for the dbus-python addons is perhaps > unfortunate; it's really more like "event dispatcher integration glue". I know — I have been playing with that stuff a bit in past :) >> If you don't remove these packages from Recommends, then at least please >> replace them with their modern PyQt5 alternatives, i.e.: >> >> python-qt4-dbus → python-dbus.mainloop.pyqt5 >> python3-dbus.mainloop.qt → python3-dbus.mainloop.pyqt5 > > I've done that in git for now, while we decide whether to remove them > altogether. Thanks! -- Dmitry Shachnev
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