Canonical Voices

Posts tagged with 'python'


I released PyGObject 3.3.4. This is mostly a bug fix only release to fix existing API. Highlights are that lists of GVariants and other corner cases are now working correctly when being passed from C to Python, and that calling help() on a GI module now does something sensible.

Thanks to all contributors!

Complete list of changes:

  • Drop bogus filter_new() conversion (Martin Pitt) (#679999)
  • Fix help() for GI modules (Martin Pitt) (#679804)
  • Skip gi.CallbackInfo objects from a module’s dir() (Martin Pitt) (#679804)
  • Fix __path__ module attribute (Martin Pitt)
  • Fix some child ? getChild() false positives (Joe R. Nassimian) (#680004)
  • Fix array handling for interfaces, properties, and signals (Mikkel Kamstrup Erlandsen) (#667244)
  • Add conversion of the Gdk.PropMode constants to script (Manuel Quiñones) (#679775)
  • Add the same rules for pack_start to convert pack_end (Manuel Quiñones) (#679760)
  • Add error-checking for the case where _arg_cache_new() fails (Dave Malcolm) (#678914)
  • Add conversion of the Gdk.NotifyType constants to script (Manuel Quiñones) (#679754)
  • Fix PyObject_Repr and PyObject_Str reference leaks (Simon Feltman) (#675857)
  • [API add] Gtk overrides: Add TreePath.__len__() (Martin Pitt) (#679199)
  • GLib.Variant: Fix repr(), add proper str() (Martin Pitt) (#679336)
  • m4/python.m4: Update Python version list (Martin Pitt)
  • Remove “label” property from Gtk.MenuItem if it is not set (Micah Carrick) (#670575)

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I just received confirmation that my request for a PyGObject hackfest has been approved by the GUADEC organizers.

If you are developing GObject-introspection based Python applications and have some problems with PyGObject, this is the time and place to get to know each other, getting bugs fixed, learn about pygobject’s innards, or update libraries to become introspectable. I will prepare a list of easy things to look into if you are interested in learning about and getting involved in PyGObject’s development.

See you on July 30th in A Coruña!


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I released PyGObject 3.3.3.

The most notable changes are that you can now access methods (and other identifiers) which are Python keywords, PyGObject automatically escapes them now by appending a ‘_’. For example, you can now call myGdkWindow.raise_() or GLib.Thread.yield_() instead of having to resort to the previous workaround getattr(myGdkWindow, 'raise')().

This version also restores the deprecated get_data() and set_data() methods. They were never really meant to be used from Python programs, they can potentially mess up your program and cause crashes, and do not give you anything that regular Python object properties would not already provide in a much safer way (i. e. just write = 'bar' instead of my_obj.set_data('foo', 'bar')). Apparently some software projects are using them, so they will now raise a deprecation warning and be removed for the GNOME 3.8 cycle instead.

Thanks to all contributors!

Complete list of changes:

  • Remove obsolete release-tag make target (Martin Pitt)
  • Do not do any python calls when GObjects are destroyed after the python interpreter has been finalized (Simon Schampijer) (#678046)
  • Do not change constructor-only “type” Window property (Martin Pitt) (#678510)
  • Escape identifiers which are Python keywords (Martin Pitt) (#676746)
  • Fix code for PEP-8 violations detected by the latest pep8 checker. (Martin Pitt)
  • Fix crash in GLib.find_program_in_path() (Martin Pitt) (#678119)
  • Revert “Do not bind gobject_get_data() and gobject_set_data()” (Martin Pitt) (#641944)
  • GVariant: Raise proper TypeError on invalid tuple input (David Keijser) (#678317)

Update:Just released to fix a regresssion from the keyword escaping patch. It also escaped enum and flags names, but as they are translated to upper case they are never keywords.

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I just released PyGObject 3.3.2, (almost) in time for tomorrow’s GNOME 3.5.2 release. No API breaks or new features this time, just lots of bug fixes and some minor API completions. My personal favorite is making closure calls work with GVariant arguments, which I finally figured out after over half a year; this finally unblocks making GDBus fully introspectable with not too much additional work, only that in the meantime dbus-python was ported to Python 3 so that the need for it is actually a lot smaller now.

Thanks to all contributors!

Complete list of changes:

  • foreign: Register cairo.Path and cairo.FontOptions foreign structs (Bastian Winkler) (#677388)
  • Check types in GBoxed assignments (Marien Zwart) (#676603)
  • [API add] Gtk overrides: Add TreeModelRow.get_previous() (Bastian Winkler) (#677389)
  • [API add] Add missing GObject.TYPE_VARIANT (Bastian Winkler) (#677387)
  • Fix boxed type equality (Jasper St. Pierre) (#677249)
  • Fix TestProperties.testBoxed test (Jose Rostagno) (#676644)
  • Fix handling of by-reference structs as out parameters (Carlos Garnacho) (#653151)
  • tests: Add more vfunc checks for GIMarshallingTestsObject (Martin Pitt)
  • Test caller-allocated GValue out parameter (Martin Pitt) (#653151)
  • GObject.bind_property: Support transform functions (Bastian Winkler) (#676169)
  • Fix lookup of vfuncs in parent classes (Carlos Garnacho) (#672864)
  • tests/ Fix whitespace (Martin Pitt)
  • gi: Support zero-terminated arrays with length arguments (Jasper St. Pierre) (#677124)
  • [API add] Add GObject.bind_property method (Simon Feltman) (#675582)
  • pygtkcompat: Correctly set flags (Jose Rostagno) (#675911)
  • Gtk overrides: Implement __delitem__ on TreeModel (Jose Rostagno) (#675892)
  • Gdk Color override should support red/green/blue_float properties (Simon Feltman) (#675579)
  • Support marshalling of GVariants for closures (Martin Pitt) (#656554)
  • _pygi_argument_from_object(): Check for compatible data type (Martin Pitt)
  • pygtkcompat: Fix color conversion (Martin Pitt)
  • test_gi: Check setting properties in constructor (Martin Pitt)
  • Support getting and setting GStrv properties (Martin Pitt)
  • Support defining GStrv properties from Python (Martin Pitt)
  • Add GObject.TYPE_STRV constant (Martin Pitt)
  • Unref GVariants when destroying the wrapper (Martin Pitt) (#675472)
  • Fix TestArrayGVariant test cases (Martin Pitt)
  • pygtkcompat: Add gdk.pixbuf_get_formats compat code (Jose Rostagno) (#675489)
  • pygtkcompat: Add some more compat functions (Jose Rostagno) (#675489)
  • Fix tests for Python 3 (Martin Pitt)
  • Fix building with –disable-cairo (Martin Pitt)
  • tests: Fix deprecated assertions (Martin Pitt)
  • Run tests with MALLOC_PERTURB_ (Martin Pitt)

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I just uploaded Apport 2.1 to Quantal. A big change in that version is that the whole code now works with both Python 2 and 3, except for the launchpadlib crash database backend (as we do not yet have a python3-launchpadlib package).

I took some care that apport report objects get along with both strings (unicode type in Python 2) and byte arrays (str type in Python 2) in values, so most package hooks should still work. However, now is the time to check whether they also work with Python 3, to make the impending transition to Python 3 easier.

However, you need to watch out if you use projects or scripts which directly use python-apport to process reports: The open(), write(), and write_mime() methods now require the passed file descriptors to be open in binary mode. You will get an exception otherwise.

A common pattern so far has been code like

  report = apport.Report()

This needs to be changed to

  report = apport.Report()
  with open('myfile.crash', 'rb') as f:

The “with” context is not strictly required, but it takes care of timely closing the files again. This avoids ResourceWarning spew when you run this in test suites or enable warnings.

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This announcement comes very late (a week after release), but better late than never..

The first PyGObject 3.3 series release is now out, with lots of yummy fixes and improvements. Dieter, Sebastian, and I went through a round of bugzilla spring cleaning to clean up old bugs, fix simple bugs, and apply good patches that were waiting, so as a result the patch queue is now almost empty and PyGObject works better than ever.

There was also quite some work on the test suite: it became a lot stricter and robust, and now also enforces PEP8 compatibility and absence of pyflake errors of the code.

One small but handy new feature is that the freeze_notify() and handler_block() methods are now context managers, i. e. they automatically call the corresponding thaw_notify()/handler_unblock() at the end of the with statement in an exception-safe way. ((#672324)

There are almost no API changes in this release, so it should work fine with GNOME 3.4 and applications developed with pygobject 3.2. The one exception is the removal of the Gobject.get_data() and Gobject.set_data() methods. They were prone to errors and crashes as they are not safely bindable, and in Python you can and should just use normal Python object attributes instead.

Complete list of changes:

  • GSettings: allow extra keyword arguments (Giovanni Campagna) (#675105)
  • pygtkcompat: Correct Userlist module use (Jose Rostagno) (#675084)
  • Add release-news make rule (Martin Pitt)
  • Add “make check.nemiver” target (Martin Pitt)
  • Test flags and enums in GHash values (Martin Pitt) (#637466)
  • tests: Activate test_hash_in and apply workaround (Martin Pitt) (#666636)
  • Add special case for Gdk.Atom array entries from Python (Martin Pitt) (#661709)
  • test_gdbus: Call GetConnectionUnixProcessID() with correct signature (Martin Pitt) (#667954)
  • Add test case for Gtk.ListStore custom sort (Martin Pitt) (#674475)
  • GTK overrides: Add missing keyword arguments (Martin Pitt) (#660018)
  • Add missing override for TreeModel.iter_previous() (Martin Pitt) (#660018)
  • Drop obsolete drag method conversions (Martin Pitt) (#652860)
  • tests: Replace deprecated assertEquals() with assertEqual() (Martin Pitt)
  • Plug tiny leak in constant_info_get_value (Paolo Borelli) (#642754)
  • Fix len_arg_index for array arguments (Bastian Winkler) (#674271)
  • Support defining GType properties from Python (Martin Pitt) (#674351)
  • Handle GType properties correctly (Bastian Winkler) (#674351)
  • Add missing GObject.TYPE_GTYPE (Martin Pitt)
  • Fix for Python 3 (Martin Pitt)
  • Make callback exception propagation test stricter (Martin Pitt) (#616279)
  • Add context management to freeze_notify() and handler_block(). (Simon Feltman) (#672324)
  • Add support for GFlags properties (Martin Pitt) (#620943)
  • Wrap GLib.Source.is_destroyed() method (Martin Pitt) (#524719)
  • Fix error message when trying to override a non-GI class (Martin Pitt) (#646667)
  • Fix segfault when accessing __grefcount__ before creating the GObject (Steve Frécinaux) (#640434)
  • Do not bind gobject_get_data() and gobject_set_data() (Steve Frécinaux) (#641944)
  • Add test case for multiple GLib.MainLoop instances (Martin Pitt) (#663068)
  • Add a ccallback type which is used to invoke callbacks passed to a vfunc (John (J5) Palmieri) (#644926)
  • Regression test: marshalling GValues in GHashTable (Alberto Mardegan) (#668903)
  • Update .gitignore (Martin Pitt)
  • Fix “distcheck” and tests with out-of-tree builds (Martin Pitt)
  • Add a pep8 check to the makefile (Johan Dahlin) (#672627)
  • PEP8 whitespace fixes (Johan Dahlin) (#672627)
  • PEP8: Remove trailing ; (Johan Dahlin) (#672627)
  • tests: Replace deprecated Python API (Martin Pitt)
  • Fail tests if they use or encounter deprecations (Martin Pitt)
  • Do not run tests in two phases any more (Martin Pitt)
  • test_overrides: Find local gsettings schema with current glib (Martin Pitt)
  • Add GtkComboBoxEntry compatibility (Paolo Borelli) (#672589)
  • Correct review comments from Martin (Johan Dahlin) (#672578)
  • Correct pyflakes warnings/errors (Johan Dahlin) (#672578)
  • Make tests fail on CRITICAL logs, too, and apply to all tests (Martin Pitt)
  • Support marshalling GI_TYPE_TAG_INTERFACE (Alberto Mardegan) (#668903)
  • Fix warnings on None values in added tree/list store rows (Martin Pitt) (#672463)
  • pygtkcompat test: Properly clean up PixbufLoader (Martin Pitt)

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I just released a new pygobject version 3.1.92, for this week’s GNOME 3.3.92. This was my first-ever GNOME release (yay!), so please bear with me.

One highlight of this release is the new pygtkcompat module, contributed by Johan Dahlin. It provides backwards compatibility to pygtk far beyond to what the Gtk overrrides do, and also includes some shims for the old static webkit, gudev, and other modules. You can, and have to, enable them individually:

import gi.pygtkcompat

# enable "gobject" and "glib" modules

import glib
import gtk

Now you can use gtk.Window(), glib.timeout_add() etc. as before, and these will be transparently be converted into their modern GI counterparts. Please note that this is still in its infancy, and also mostly meant to ease the porting to GI. It’s not something we’ll keep forever.

Thanks to Michel Dänzer this release now also works properly on big-endian machines.

I mostly worked on fixing the calls of methods which take a list of GValues as arguments, such as Gtk.ListStore.insert_with_valuesv() and similar functions, and made the override API for tree models (append() etc. with providing row data) atomic wrt. the signals it sends out.

I want to thank Johan and Paolo for the nice teamwork with reviewing each other’s patches. That’s open source at its best!

Complete list of changes:

  • Correct Gtk.TreePath.__iter__ to work with Python 3 (Johan Dahlin)
  • Fix test_everything.TestSignals.test_object_param_signal test case (Martin Pitt)
  • Add a PyGTK compatibility layer (Johan Dahlin)
  • pygtkcompat: Remove first argument for get_origin() (Johan Dahlin)
  • Fix to work with Python 3 (Martin Pitt)
  • GtkViewport: Add a default values for the adjustment constructor parameters (Johan Dahlin)
  • GtkIconSet: Add a default value for the pixbuf constructor parameter (Johan Dahlin)
  • PangoLayout: Add a default value for set_markup() (Johan Dahlin)
  • Gtk[HV]Scrollbar: Add a default value for the adjustment constructor parameter (Johan Dahlin)
  • GtkToolButton: Add a default value for the stock_id constructor parameter (Johan Dahlin)
  • GtkIconView: Add a default value for the model constructor parameter (Johan Dahlin)
  • Add a default value for column in Gtk.TreeView.get_cell_area() (Johan Dahlin)
  • Atomic inserts in Gtk.{List,Tree}Store overrides (Martin Pitt)
  • Fix Gtk.Button constructor to accept use_stock parameter (Martin Pitt)
  • Correct bad rebase, remove duplicate Window (Johan Dahlin)
  • Add bw-compatible arguments to Gtk.Adjustment (Johan Dahlin)
  • GtkTreePath: make it iterable (Johan Dahlin)
  • Add a default argument to TreeModelFilter.set_visible_func() (Johan Dahlin)
  • Add a default argument to Gtk.TreeView.set_cursor (Johan Dahlin)
  • Add a default argument to Pango.Context.get_metrics() (Johan Dahlin)
  • Fix double-freeing GValues in arrays (Martin Pitt)
  • Renamed “property” class to “Property” (Simon Feltman)
  • Fix Python to C marshalling of GValue arrays (Martin Pitt)
  • Correct the Gtk.Window hierarchy (Johan Dahlin)
  • Renamed getter/setter instance attributes to fget/fset respectively. (Simon Feltman)
  • Add Gtk.Arrow/Gtk.Window constructor override (Johan Dahlin)
  • Fix marshalling to/from Python to work on big endian machines. (Michel Dänzer)
  • Use gi_cclosure_marshal_generic instead of duplicating it. (Michel Dänzer)
  • Override Gtk.TreeView.get_visible_range to fix return (René Stadler)
  • Plug memory leak in _is_union_member (Paolo Borelli)
  • tests: Split TestInterfaces into separate tests (Sebastian Pölsterl)
  • README: Update current maintainers (Martin Pitt)

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PackageKit has a “WhatProvides” API for mapping distribution independent concepts to particular package names. For example, you could ask “which packages provide a decoder for AC3 audio files?

$ pkcon what-provides  "gstreamer0.10(decoder-audio/ac3)"
Installed   	gstreamer0.10-plugins-good-	GStreamer plugins from the "good" set
Available  	gstreamer0.10-plugins-ugly-0.10.18-3ubuntu4.amd64	GStreamer plugins from the "ugly" set

This is the kind of question your video player would ask the system if it encounters a video it cannot play. In reality they of course use the D-BUS or the library API, but it’s easier to demonstrate with the PackageKit command line client.

PackageKit provides a fair number of those concepts; I recently added LANGUAGE_SUPPORT for packages which provide dictionaries, spell checkers, and other language support for a given language or locale code.

However, PackageKit’s apt backend does not actually implement a lot of these (only CODEC and MODALIAS), and aptdaemons’s PackageKit compatibility API does not implement any. That might be because their upstreams do not know enough how to do the mapping for a particular distro/backend, because doing so involves distro specific code which should not go into upstreams, or simply because of the usual chicken-egg problem of app developers rather doing their own thing instead of using generic APIs.

So this got discussed between Sebastian Heinlein and me, and voila, there it is: it is now very easy to provide Python plugins for “what-provides” to implement any of the existing types. For example, language-selector now ships a plugin which implements LANGUAGE_SUPPORT, so you can ask “which packages do I need for Chinese in China” (i. e. simplified Chinese)?

$ pkcon what-provides "locale(zh_CN)"
Available   	firefox-locale-zh-hans-10.0+build1-0ubuntu1.all	Simplified Chinese language pack for Firefox
Available   	ibus-sunpinyin-2.0.3-2.amd64            	sunpinyin engine for ibus
Available   	language-pack-gnome-zh-hans-1:12.04+20120130.all	GNOME translation updates for language Simplified Chinese
Available   	ttf-arphic-ukai-0.2.20080216.1-1.all    	"AR PL UKai" Chinese Unicode TrueType font collection Kaiti style

Rodrigo Moya is currently working on implementing the control-center region panel redesign in a branch. This uses exactly this feature.

In Ubuntu we usually do not use PackageKit itself, but aptdaemon and its PackageKit API compatibility shim python-aptdaemon.pkcompat. So I ported that plugin support for aptdaemon-pkcompat as well, so plugins work with either now. Ubuntu Precise got the new aptdaemon (0.43+bzr769-0ubuntu1) and language-selector (0.63) versions today, so you can start playing around with this now.

So how can you write your own plugins? This is a trivial, although rather nonsense example:

from packagekit import enums

def my_what_provides(apt_cache, provides_type, search):
    if provides_type in (enums.PROVIDES_CODEC, enums.PROVIDES_ANY):
        return [apt_cache["gstreamer-moo"]]
        raise NotImplementedError('cannot handle type ' + str(provides_type))

The function gets an apt.Cache object, one of enums.PROVIDES_* and the actual search type as described in the documentation (above dummy example does not actually use it). It then decides whether it can handle the request and return a list of apt.package.Package objects (i. e. values in an apt.Cache map), or raise a NotImplementedError otherwise.

You register the plugin through Python pkg-resources in your (this needs setuptools):



You can register arbitrarily many plugins, they will be all called and their resulting package lists joined.

All this will hopefully help a bit to push distro specifics to the lowest possible levels, and use upstream friendly and distribution agnostic APIs in your applications.

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On my 8 hour train ride to Budapest last Sunday I finally worked on making libxklavier introspectable. Thanks to Sergey’s fast review the code now landed in trunk. I sent a couple of refinements to the bug report still, but those are mostly just icing on the cake, the main functionality of getting and setting keyboard layouts is working nicely now (see the example script).

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As a followup action to my recent Talk about PyGI I now re-used my notes to provide some real wiki documentation.

It would be great if you could add package name info for Fedora/SUSE/etc., and perhaps add more example links for porting different kinds of software! Please also let me know if you have suggestions how to improve the structure of the page.

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On next Monday this cycle’s Ubuntu Application Developer Week classes will start.

The topic that kept me busy most in this cycle was Python gobject-introspection, and porting pygtk2 apps to PyGI (see my initial steps and my report from the PyGI hackfest.)

To spread the love, there will be two talks about this next week: On Monday 17:00 UTC the very Tomeu Vizoso himself will explain what gobject-introspection (“GI”) is, why we need it, and how library developers use it to ship a good and useful GI binding (“typelib”) for application developers. I will then follow up on Tuesday 16:00 UTC about the app developer side, in particular how to use the GI typelibs in Python, and how to port PyGTK2 applications to PyGI.

For the most part these sessions are distribution neutral (we don’t have any special sauce for this in Debian/Ubuntu, it all happened right upstream :-) ); only a very small fraction of it (where I explain package names, etc.) will be specific to Debian/Ubuntu, but shouldn’t be hard to apply to other distributions as well.

So please feel invited to join, and bombard us with questions!

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GNOME 3.0 and Ubuntu Natty are currently undergoing a major architectural shift from GTK 2.0 to 3.0. Part of this is that the previous set of manually maintained language bindings, such as PyGTK, are being deprecated in favor of GObject Introspection, a really cool technology!

For us this means that we have to port all our PyGTK applications from PyGTK 2 to gobject-introspection and GTK 3.0 at the same time. I started with that for my own projects (Apport and Jockey) a few days ago, and along the way encountered a number of problems. They are being fixed (particular thanks to the quick responsiveness of John Palmieri!), so I guess after a few of those iterations, porting should actually become straight forward and solid.

So now I’m proud to announce Apport 1.16 which is now fully working with GTK 3.0 and pygobject-introspection. I just uploaded it to Ubuntu Natty, where it can get some wider testing. I also have a pygi/GTK3.0 branch for Jockey, which is also mostly working now, but it’s blocked on the availability of a GIR for AppIndicator. Once that lands, I’ll release and upload the Jockey as well.

For other people working on porting, these are the bugs and problems I’ve encountered:

  • [pygobject] GtkMessageDialog constructors did not work at all. This was fixed in pygobject 2.27, so it works fine in Natty, but there is little to no chance of making these work in Ubuntu 10.10.
  • [pygobject] Gtk.init_check() crashes (upstream bug). It’s not strictly necessary, though, just avoids crashes (and crash reports) when calling it without a $DISPLAY. I’ll put that back once that gets fixed.
  • [pygobject] You can’t pass unicode objects as method arguments or property values (upstream bug). Method arguments were recently fixed in upstream git head, and I backported it to the Natty package, so these work now. Property values are still outstanding. The workaround for both is to convert unicode values to bytes with .encode('UTF-8') everywhere.
  • [pygobject] is a great help which automates most of the mechanical rewriting work and thus gets you 90% of the porting done automatically. It’s currently missing MessageDialog constants, and is a bit inconvenient to call. I sent two patches upstream (upstream bug) which improve this.
  • [GIR availability] libnotify did not build a GIR yet (upstream bug). This was fixed in upstream git head with some contributions of mine, and I uploaded it to Natty. This works quite well now, although add_action() crashes on passing the callback. This is still to be investigated.
  • [GIR availability] There is no Application Indicator GIR, as already mentioned. Our DX team and Ken VanDine are working on this, so this should get fixed soon.
  • [GTK] Many dialogs now scale in a very ugly manner: Instead of resizing the contents, the dialog just grows huge outer padding. This is due to a change of the default “fill” property, and apparently is not fully understood yet (upstream bug). As a workaround I explicitly added the fill property to the top-level GTKBox in my GTKBuilder .ui files. (Note that this happens in C as well, it’s not a GI specific bug.)
  • [GTK] Building GtkRadioButton groups is currently a bit inconvenient and requires special-casing for the first group member, due to some missing annotations. I sent a patch upstream which fixes that (upstream bug).
  • [GTK] After initial porting, a lot of my dialogs got way too narrow with wrapped labels and text, because GTK 3 changed the behaviour and handling of widget and window sizes. This is intended, not a bug, but it does require some adaptions in the GtkBuilder files and also in the code. The GTK 2 ? 3 migration guide has a section about it.

Despite those, I’m impressed how well gobject-introspection already works. It was relatively painless for me to generate a GIR from a libnotify (thanks to the annotations already being mostly correct for building the documentation) and use it from Python. In another couple of months this will be rock solid, and porting our bigger pygtk projects like ubiquity and software-center will hopefully become feasible.

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(Update: Link to Tomeu’s blog post, repost for

Last week I was in Prague to attend the GNOME/Python 2011 Hackfest for gobject-introspection, to which Tomeu Vizoso kindly invited me after I started working with PyGI some months ago. It happened at a place called brmlab which was quite the right environment for a bunch of 9 hackers: Some comfy couches and chairs, soldering irons, lots of old TV tubes, chips, and other electronics, a big Pirate flag, really good Wifi, plenty of Club Mate and Coke supplies, and not putting unnecessary effort into mundane things like wallpapers.

It was really nice to get to know the upstream experts John (J5) Palmieri and Tomeu Vizoso (check out Tomeu’s blog post for his summary and some really nice photos). When sitting together in a room, fully focussing on this area for a full week, it’s so much easier to just ask them about something and getting things done and into upstream than on IRC or bugzilla, where you don’t know each other personally. I certainly learned a lot this week (and not only how great Czech beer tastes :-) )!

So what did I do?

Application porting

After already having ported four Ubuntu PyGTK applications to GI before (apport, jockey, aptdaemon, and language-selector),
my main goal and occupation during this week was to start porting a bigger PyGTK application. I picked system-config-printer, as it’s two magnitudes bigger than the previous projects, exercises quite a lot more of the GTK GI bindings, and thus also exposes a lot more GTK annotation and pygobject bugs. This resulted in a new pygi s-c-p branch which has the first 100 rounds of “test, break, fix” iterations. It now at least starts, and you can do a number of things with it, but a lot of functionality is still broken.

As a kind of “finger exercise” and also to check for how well pygi-convert works for small projects now, I also ported computer-janitor. This went really well (I had it working after about 30 minutes), and also led me to finally fixing the unicode vs. str mess for GtkTreeView that you got so far with Python 2.x.

pygobject and GTK fixes

Porting system-config-printer and computer-janitor uncovered a lot of opportunities to improve, a big “perl -e” kind of script to do the mechanical grunt work of the porting process. It doesn’t fix up changed signatures (such as adding missing arguments which were default arguments in PyGTK, or the ubiquitous “user_data” argument for signal handlers), but at least it gets a lot of namespaces, method, and constant names right.

I also fixed three annotation fixes in GTK+. We also collaboratively reviewed and tested Pavel’s annotation branch which helped to fix tons of problems, especially after Steve Frécinaux’s excellent reference leak fix, so if you play around with current pygobject git head, you really also have to use the current GTK+ git head.

Speaking of which, if you want to port applications and always stay on top of the pygobject/GTK development without having to clutter your package system with “make install”s of those, it works very well to have this in your ~/.bashrc:

export GI_TYPELIB_PATH=$HOME/projects/gtk/gtk:$HOME/projects/gtk/gdk
export PYTHONPATH=$HOME/projects/pygobject

Better GVariant/GDBus support

The GNOME world is moving from the old dbus-glib python bindings to GDBus, which is integrated into GLib. However, dbus-python exposed a really nice and convenient way of doing D-Bus calls, while using GDBus from Python was hideously complicated, especially for nontrivial arguments with empty or nested arrays:

from gi.repository import Gio, GLib
from gi._gi import variant_type_from_string

d = Gio.bus_get_sync(Gio.BusType.SESSION, None)
notify = Gio.DBusProxy.new_sync(d, 0, None, 'org.freedesktop.Notifications',
    '/org/freedesktop/Notifications', 'org.freedesktop.Notifications', None)

vb = GLib.VariantBuilder()
vb.add_value(GLib.Variant('s', 'test'))
vb.add_value(GLib.Variant('u', 1))
vb.add_value(GLib.Variant('s', 'gtk-ok'))
vb.add_value(GLib.Variant('s', 'Hello World!'))
vb.add_value(GLib.Variant('s', 'Subtext'))
# add an empty array
eavb = GLib.VariantBuilder()
# add an empty dict
eavb = GLib.VariantBuilder()
vb.add_value(GLib.Variant('i', 10000))
args = vb.end()

result = notify.call_sync('Notify', args, 0, -1, None)
id = result.get_child_value(0).get_uint32()
print id

So I went to making the GLib.Variant constructor work properly with nested types and boxed variants, adding Pythonic GVariant iterators and indexing (so that you can treat GVariant dictionaries/arrays/tuples just like their Python equivalents), and finally a Variant.unpack() method for converting the return value of a D-Bus call back into a native Python data type. This looks a lot friendlier now:

from gi.repository import Gio, GLib

d = Gio.bus_get_sync(Gio.BusType.SESSION, None)
notify = Gio.DBusProxy.new_sync(d, 0, None, 'org.freedesktop.Notifications',
    '/org/freedesktop/Notifications', 'org.freedesktop.Notifications', None)

args = GLib.Variant('(susssasa{sv}i)', ('test', 1, 'gtk-ok', 'Hello World!',
    'Subtext', [], {}, 10000))
result = notify.call_sync('Notify', args, 0, -1, None)
id = result.unpack()[0]
print id

I also prepared another patch in GNOME#640181 which will provide the icing on the cake, i. e. handle the variant building/unpacking transparently and make the explicit call_sync() unnecessary:

from gi.repository import Gio, GLib

d = Gio.bus_get_sync(Gio.BusType.SESSION, None)
notify = Gio.DBusProxy.new_sync(d, 0, None, 'org.freedesktop.Notifications',
    '/org/freedesktop/Notifications', 'org.freedesktop.Notifications', None)

result = notify.Notify('(susssasa{sv}i)', 'test', 1, 'gtk-ok', 'Hello World!',
            'Subtext', [], {}, 10000)
print result[0]

I hope that I can get this reviewed and land this soon.

Thanks to our sponsors!

Many thanks to the GNOME Foundation and Collabora for sponsoring this event!

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For a test suite I need to create a local SSL-enabled HTTPS server in my Python project. I googled around and found various recipes using pyOpenSSL, but all of those are quite complicated, and I didn’t even get the referenced one to work.

Also, Python has shipped its own built-in SSL module for quite a while. After reading some docs and playing around, I eventually got it to work with a remarkably simple piece of code using the builtin ssl module:

import BaseHTTPServer, SimpleHTTPServer
import ssl

httpd = BaseHTTPServer.HTTPServer(('localhost', 4443), SimpleHTTPServer.SimpleHTTPRequestHandler)
httpd.socket = ssl.wrap_socket (httpd.socket, certfile='path/to/localhost.pem', server_side=True)

(I use port 4443 so that I can run the tests as normal user; the usual port 443 requires root privileges).

Way to go, Python!

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These days I often use launchpadlib in my projects for scripting access/modifications in Launchpad. While launchpadlib has quite a good API documentation, this only covers the method calls, not the attributes or collections. So it often takes some poking and trying until you figure out how to access/change things.

I found myself typing the same things over and over, so I finally wrote a little script called lpshell:

#!/usr/bin/python -i
import code, os, sys
from launchpadlib.launchpad import Launchpad, STAGING_SERVICE_ROOT, EDGE_SERVICE_ROOT
lp = Launchpad.login_with('test', STAGING_SERVICE_ROOT)

This logs into Launchpad and gives you an interactive Python shell with an “lp” object:

$ lpshell
>>> lp.bugs[439482].duplicate_of

Update: I committed this to ubuntu-dev-tools now, renamed to lp-shell for consistency with the other lp-* commands.

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