Debian Bug report logs - #802659
dbus-python: Please drop recommends on PyQt4 packages

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Dmitry Shachnev <mitya57@debian.org>

To: submit@bugs.debian.org

Subject: dbus-python: Please drop recommends on PyQt4 packages

Date: Thu, 22 Oct 2015 12:29:54 +0300

[Message part 1 (text/plain, inline)]

Source: dbus-python
Version: 1.2.0-2
Severity: minor
Tags: patch

Dear Maintainer,

Attached is a patch that does the following:

  Drop obsolete recommendations of Qt 4 packages

  * python-qt4-dbus is a replacement for dbus-python; if one uses one package,
    he will not need the other.
  * python3-dbus.mainloop.qt is a package providing support for Qt (4.x) main
    loop. However, Qt uses GLib main loops on UNIX systems by default, so this
    package is needed very rarely and we should not recommend it.

  In the description of python-dbus-dev, replace dbus.mainloop.qt with
  dbus.mainloop.pyqt5, which is the modern successor of dbus.mainloop.qt.

  Also, drop the alternative recommendation for python-gobject-2. That
  package has been deprecated for a long time and we want to remove it from
  the archive as soon as possible.

Please consider applying it.

--
Dmitry Shachnev

[0001-Drop-obsolete-recommendations-of-Qt-4-packages.patch (text/x-diff, attachment)]

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Message #10 received at 802659@bugs.debian.org (full text, mbox, reply):

From: Simon McVittie <smcv@debian.org>

To: Dmitry Shachnev <mitya57@debian.org>, 802659@bugs.debian.org

Cc: debian-qt-kde@lists.debian.org

Subject: Re: Bug#802659: dbus-python: Please drop recommends on PyQt4 packages

Date: Wed, 20 Jan 2016 09:15:24 +0000

Sorry for the delay in responding to this; dbus-python hasn't been high
on my priority list.

On Thu, 22 Oct 2015 at 12:29:54 +0300, Dmitry Shachnev wrote:
>   Drop obsolete recommendations of Qt 4 packages
...
>   * python3-dbus.mainloop.qt is a package providing support for Qt (4.x) main
>     loop. However, Qt uses GLib main loops on UNIX systems by default, so this
>     package is needed very rarely and we should not recommend it.

I'd be happy enough to do this, but I'd like to give the Qt/KDE
maintainers (Cc'd) the opportunity to object first, so that if I get
bug reports asking me to revert the change because someone feels that
python[3]-gi is insufficiently desktop-neutral, I can point the bug
reporter to the relevant discussion and close the bug.

The library can be used without main loop support, and it doesn't
really care which main loop glue you use (options are currently GLib,
(GLib via) Qt, or E); but the majority of its functionality relies
on having *some* main loop glue for dbus-python, and then running a
compatible main loop in your program.  I included the Recommends so
that "apt install python{,3}-dbus" would give users enough modules to
run locally-written programs similar to dbus-python's own examples.
See <https://bugs.debian.org/656230> for further context.

(Anything that specifically imports dbus.mainloop.whatever should of course
continue to depend on the appropriate package.)

This main loop glue nonsense is an artefact of dbus-python trying hard
to be non-desktop-specific. With hindsight, that was a bad idea, and
these days I much prefer self-contained D-Bus implementations/bindings
(GDBus, QtDBus, sd-bus) that assume a particular main-loop framework
and can benefit from being properly integrated with it.

>   * python-qt4-dbus is a replacement for dbus-python; if one uses one package,
>     he will not need the other.

Really? It looks a lot like a direct equivalent of python3-dbus.mainloop.qt
to me:

% dpkg -L python-qt4-dbus
[... the usual /usr/share/doc noise ...]
[... some directories ... ]
/usr/lib/python2.7/dist-packages/dbus/mainloop/qt.so

Its name is presumably for historical reasons; if it was created today,
it would be named python-dbus.mainloop.qt.

At the time dbus-python was written, PyQt did not bind QtDBus; now it
does (which I believe was partially a response to how long it took to
make dbus-python work in Python 3), and I would advise developers who are
using Python with Qt to consider using the QtDBus bindings in preference
to dbus-python. dbus-python is not actually a great API, and has
several historical design mistakes, which we can't correct because its
most significant advantage over other D-Bus bindings/implementations
is compatibility with older versions of itself. I haven't tried QtDBus
but I suspect it may be better, or at least present a more Qt-like API.

>   In the description of python-dbus-dev, replace dbus.mainloop.qt with
>   dbus.mainloop.pyqt5, which is the modern successor of dbus.mainloop.qt.

Done in git, thanks.

>   Also, drop the alternative recommendation for python-gobject-2. That
>   package has been deprecated for a long time and we want to remove it from
>   the archive as soon as possible.

Also done, thanks.

I'll apply the remaining changes (losing the Qt equivalents from
Recommends) if there's consensus that this is what people who like
Qt want me to do.

    S

Message #15 received at 802659@bugs.debian.org (full text, mbox, reply):

From: Dmitry Shachnev <mitya57@debian.org>

To: Simon McVittie <smcv@debian.org>

Cc: 802659@bugs.debian.org, pkg-kde-talk@lists.alioth.debian.org

Subject: Re: Bug#802659: dbus-python: Please drop recommends on PyQt4 packages

Date: Tue, 26 Jan 2016 13:37:26 +0300

[Message part 1 (text/plain, inline)]

Hi Simon,

On Wed, Jan 20, 2016 at 09:15:24AM +0000, Simon McVittie wrote:
> Sorry for the delay in responding to this; dbus-python hasn't been high
> on my priority list.

No problem!

> On Thu, 22 Oct 2015 at 12:29:54 +0300, Dmitry Shachnev wrote:
>>   Drop obsolete recommendations of Qt 4 packages
> ...
>>   * python3-dbus.mainloop.qt is a package providing support for Qt (4.x) main
>>     loop. However, Qt uses GLib main loops on UNIX systems by default, so this
>>     package is needed very rarely and we should not recommend it.
>
> I'd be happy enough to do this, but I'd like to give the Qt/KDE
> maintainers (Cc'd) the opportunity to object first, so that if I get
> bug reports asking me to revert the change because someone feels that
> python[3]-gi is insufficiently desktop-neutral, I can point the bug
> reporter to the relevant discussion and close the bug.

The list you added is mostly for robots, the one we actually use is what I
CCed now. Though I was filing this bug with my Qt/PyQt co-maintainer hat,
so that's probably not much needed :)

> The library can be used without main loop support, and it doesn't
> really care which main loop glue you use (options are currently GLib,
> (GLib via) Qt, or E); but the majority of its functionality relies
> on having *some* main loop glue for dbus-python, and then running a
> compatible main loop in your program.  I included the Recommends so
> that "apt install python{,3}-dbus" would give users enough modules to
> run locally-written programs similar to dbus-python's own examples.
> See <https://bugs.debian.org/656230> for further context.

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.

So I still think these packages should not be recommended. If they are,
(Py)Qt developers will have a false assumption that they probably need them.

> (Anything that specifically imports dbus.mainloop.whatever should of course
> continue to depend on the appropriate package.)
>
> This main loop glue nonsense is an artefact of dbus-python trying hard
> to be non-desktop-specific. With hindsight, that was a bad idea, and
> these days I much prefer self-contained D-Bus implementations/bindings
> (GDBus, QtDBus, sd-bus) that assume a particular main-loop framework
> and can benefit from being properly integrated with it.
>
>>   * python-qt4-dbus is a replacement for dbus-python; if one uses one package,
>>     he will not need the other.
>
> Really? It looks a lot like a direct equivalent of python3-dbus.mainloop.qt
> to me:
> 
> % dpkg -L python-qt4-dbus
> [... the usual /usr/share/doc noise ...]
> [... some directories ... ]
> /usr/lib/python2.7/dist-packages/dbus/mainloop/qt.so
>
> Its name is presumably for historical reasons; if it was created today,
> it would be named python-dbus.mainloop.qt.

Oh, sorry, you are right and I was indeed confused by the name.

> At the time dbus-python was written, PyQt did not bind QtDBus; now it
> does (which I believe was partially a response to how long it took to
> make dbus-python work in Python 3), and I would advise developers who are
> using Python with Qt to consider using the QtDBus bindings in preference
> to dbus-python. dbus-python is not actually a great API, and has
> several historical design mistakes, which we can't correct because its
> most significant advantage over other D-Bus bindings/implementations
> is compatibility with older versions of itself. I haven't tried QtDBus
> but I suspect it may be better, or at least present a more Qt-like API.

dbus-python is still useful for those who need a simple Python API and don't
want to depend on bigger libraries like Qt and GLib/Gtk.

>>   In the description of python-dbus-dev, replace dbus.mainloop.qt with
>>   dbus.mainloop.pyqt5, which is the modern successor of dbus.mainloop.qt.
>
> Done in git, thanks.
>
>>   Also, drop the alternative recommendation for python-gobject-2. That
>>   package has been deprecated for a long time and we want to remove it from
>>   the archive as soon as possible.
>
> Also done, thanks.

Thanks!

> I'll apply the remaining changes (losing the Qt equivalents from
> Recommends) if there's consensus that this is what people who like
> Qt want me to do.

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

--
Dmitry Shachnev

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Message #20 received at 802659@bugs.debian.org (full text, mbox, reply):

From: Simon McVittie <smcv@debian.org>

To: Dmitry Shachnev <mitya57@debian.org>

Cc: 802659@bugs.debian.org, pkg-kde-talk@lists.alioth.debian.org

Subject: Re: Bug#802659: dbus-python: Please drop recommends on PyQt4 packages

Date: Tue, 26 Jan 2016 18:49:11 +0100

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?

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".

> 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.

    S

Message #25 received at 802659@bugs.debian.org (full text, mbox, reply):

From: Dmitry Shachnev <mitya57@debian.org>

To: Simon McVittie <smcv@debian.org>

Cc: 802659@bugs.debian.org, pkg-kde-talk@lists.alioth.debian.org

Subject: Re: Bug#802659: dbus-python: Please drop recommends on PyQt4 packages

Date: Wed, 27 Jan 2016 10:20:37 +0300

[Message part 1 (text/plain, inline)]

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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Message #30 received at 802659@bugs.debian.org (full text, mbox, reply):

From: Lisandro Damián Nicanor Pérez Meyer <perezmeyer@gmail.com>

To: pkg-kde-talk@lists.alioth.debian.org

Cc: Simon McVittie <smcv@debian.org>, Dmitry Shachnev <mitya57@debian.org>, 802659@bugs.debian.org

Subject: Re: Bug#802659: dbus-python: Please drop recommends on PyQt4 packages

Date: Wed, 27 Jan 2016 14:25:15 -0300

[Message part 1 (text/plain, inline)]

Hi Simon! For what it's worth Dmitry is the python-knowledgeable guy in the Qt 
packaging team. So I just trust him :)

Kinds regards, Lisandro.

-- 
Why should I care about posterity?
What's posterity ever done for me?
  -- Groucho Marx

Lisandro Damián Nicanor Pérez Meyer
http://perezmeyer.com.ar/
http://perezmeyer.blogspot.com/

[signature.asc (application/pgp-signature, inline)]

Message #35 received at 802659-close@bugs.debian.org (full text, mbox, reply):

From: Simon McVittie <smcv@debian.org>

To: 802659-close@bugs.debian.org

Subject: Bug#802659: fixed in dbus-python 1.2.2-1

Date: Mon, 22 Feb 2016 17:50:04 +0000

Source: dbus-python
Source-Version: 1.2.2-1

We believe that the bug you reported is fixed in the latest version of
dbus-python, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 802659@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Simon McVittie <smcv@debian.org> (supplier of updated dbus-python package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Format: 1.8
Date: Mon, 22 Feb 2016 16:44:00 +0000
Source: dbus-python
Binary: python-dbus python3-dbus python-dbus-dev python-dbus-dbg python3-dbus-dbg python-dbus-doc
Architecture: source
Version: 1.2.2-1
Distribution: unstable
Urgency: low
Maintainer: Utopia Maintenance Team <pkg-utopia-maintainers@lists.alioth.debian.org>
Changed-By: Simon McVittie <smcv@debian.org>
Description:
 python-dbus - simple interprocess messaging system (Python interface)
 python-dbus-dbg - debug build of the D-Bus Python 2 interface
 python-dbus-dev - main loop integration development files for python-dbus
 python-dbus-doc - Documentation for the D-Bus Python interface
 python3-dbus - simple interprocess messaging system (Python 3 interface)
 python3-dbus-dbg - debug build of the D-Bus Python 3 interface
Closes: 802659
Changes:
 dbus-python (1.2.2-1) unstable; urgency=low
 .
   * New upstream release
     - build-depend on autoconf-archive, now required for autoreconf
     - explicitly set build system to autoconf since there is now a stub
       setup.py
     - d/copyright: update
   * Switch Vcs-Git to https (see #810378)
   * Remove dbus.mainloop.qt recommendation as requested by Qt maintainers
     (Closes: #802659)
   * Run dh_install with --list-missing to guard against mistakes
   * Override lintian warnings about confusing dbus with D-Bus: we are
     careful to use both terms correctly
   * python-dbus-dev: add missing dependency on libdbus-1-dev
   * Enable build-time testing
     - build-depend on dbus
   * Add infrastructure for installed-tests for architecture-specific
     builds, and add corresponding autopkgtests
     - disable installed-tests for the architecture-indep build, which is
       only there for the documentation
     - temporarily disable the new packages for this upload,
       to avoid the NEW queue
Checksums-Sha1:
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 c2b93b1f0e4945711d6f6d232e63cb9aa3a93359 608781 dbus-python_1.2.2.orig.tar.gz
 f3a702183b216bd751d83d15cb337e5666da5c5b 16608 dbus-python_1.2.2-1.debian.tar.xz
Checksums-Sha256:
 45dc568ddfc4a20671dfe00863ec18532a6cc6435884bfc3f711dbe8bec962f5 2719 dbus-python_1.2.2-1.dsc
 f79741510cad485afba1303b43e639aacdd7ddecf3ce7c6cca0b1a849bdf8fb3 608781 dbus-python_1.2.2.orig.tar.gz
 1d1be858dc0365fb70e31e128e248c39f1a034484cfb5f1d5bb37179d8258906 16608 dbus-python_1.2.2-1.debian.tar.xz
Files:
 3b34ea96cac0a0742f868d9515a91e34 2719 devel optional dbus-python_1.2.2-1.dsc
 d1f2c7ba976d457206caf57d20b5cb5d 608781 devel optional dbus-python_1.2.2.orig.tar.gz
 1bb536f57e7b387f667a1dd7a1be12df 16608 devel optional dbus-python_1.2.2-1.debian.tar.xz

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