Changes

== Summary ==

== Summary ==

'''Sugar needs to rebase itself on new generations of its key underlying technologies: GTK+ 3 and PyGObject Introspection.''' This page aims to summarise options and community opinions around this challenging shift, and to help formulate a plan of how it will be executed. In other words, it tries to take community input, answer all the unanswered questions, and present a logical path forward that can be adopted by the developers.

'''Sugar needs to rebase itself on new generations of its key underlying technologies: GTK+ 3 and PyGObject Introspection.''' Sugar is already somewhat broken on recent distribution versions as a result of this. This page aims to summarise options and community opinions around this challenging shift, and to help formulate a plan of how it will be executed. In other words, it tries to take community input, answer all the unanswered questions, and present a logical path forward that can be adopted by the developers.

== Owner ==

== Owner ==

== Current status ==

== Current status ==

* Targeted release: (SUGAR_VERSION)

* Targeted release: <b>0.96</b> (at least for sugar-toolkit port)

* Last updated: (DATE)

* Last updated: (DATE)

* Percentage of completion: XX%

* Percentage of completion: XX%

== Detailed Description ==

== Detailed Description ==

# The move to GTK3 allows us to [http://blog.tomeuvizoso.net/2011/05/time-to-port-your-python-application-to.html keep up with our GNOME neighbours], as they improve and refine the base technologies that we share.

# The move to GTK3 allows us to [http://blog.tomeuvizoso.net/2011/05/time-to-port-your-python-application-to.html keep up with our GNOME neighbours], as they improve and refine the base technologies that we share.

# The move to PyGI is expected to result in [http://blog.tomeuvizoso.net/2009/05/reducing-sugars-memory-usage.html lower memory usage and faster startup].

# The move to PyGI is expected to result in [http://blog.tomeuvizoso.net/2009/05/reducing-sugars-memory-usage.html lower memory usage and faster startup].

# Browse has no future under GTK2, it [[Features/WebKit|needs to move to WebKit]] and that move is dependent on Sugar moving to PyGI/GTK3.

# Browse has no future under GTK2 and is '''already broken''', it [[Features/WebKit|needs to move to WebKit]] and that move is dependent on Sugar moving to PyGI/GTK3.

# Similarly, Read has a grim future under GTK2 due to static evince bindings no longer being maintained and libevince itself moved to GTK3; we need to switch to PyGI/GTK3 to be able to keep calling into evince and let the Read activity live on.

# Similarly, Read is '''already broken''' under GTK2 due to static evince bindings no longer being maintained and libevince itself moved to GTK3; we need to switch to PyGI/GTK3 to be able to keep calling into evince and let the Read activity live on.

== Implementation Plan ==

== Implementation Plan ==

One complication is that hippo usage is not limited to Sugar's core; some activities use hippo, or they pull on sugar-toolkit classes which are implemented with hippo. These are: Chat (<em>please list others here</em>).

One complication is that hippo usage is not limited to Sugar's core; some activities use hippo, or they pull on sugar-toolkit classes which are implemented with hippo. These are: Chat (<em>please list others here</em>).

=== Backwards-compatibility for activities ===

=== Backwards-compatibility for activities ===

As we do not have plentiful developer resources, I propose that the PyGTK/GTK2 version of sugar-toolkit is frozen as soon as this feature development is underway. No bugfixes or improvements, just a copy of the code at that point.

As we do not have plentiful developer resources, I propose that the PyGTK/GTK2 version of sugar-toolkit is frozen as soon as this feature development is underway. No bugfixes or improvements, just a copy of the code at that point.

The GTK3 version of sugar-toolkit would be installed under a new module named <b>sugar1</b>, distinguishing it from the frozen GTK2 <b>sugar</b> version to be removed later. All code will need extensive textual changes in moving to GTK3, changing "import sugar.foo" to "import sugar1.foo" will just be another step in that process.

 

With two versions of sugar-toolkit available, activities need a mechanism for choosing which toolkit they will use. As we require existing activities to continue working without modifications, this selection mechanism must be <em>opt-in</em> - ported activities must somehow mark themselves as being GTK3-ported, and hence will receive the GTK3 version of sugar-toolkit, and all other activities will receive the GTK2 version.

 

One easy way to achieve this would be to give the GTK3 version of sugar-toolkit a different name. The unported GTK2 activities could continue to <tt>import sugar.foo</tt> and ported GTK3 activities would <tt>import sugar1.foo</tt>. "sugar1" is chosen as an example to indicate Sugar-1.0, but other naming schemes would obviously work equally well.

 

If the community has strong desires, it would be possible maintain the <tt>sugar</tt> module name through a Python trick which could be deployed during the transition period, and then removed once the GTK2 version is dropped. Here is how it could be done:

 

* The new GTK3 version of sugar toolkit would be installed with name <tt>sugar</tt>, and the old GTK2 version would be installed with name <tt>sugar_gtk2</tt>.

* Before <tt>sugar-activity</tt> imports sugar.activity (or any other sugar-toolkit class), it would look for an empty file called "GTK3_PORTED" in the activity's directory. If present, it would run a little trick:

if not os.path.exists("GTK3_PORTED"):

    import sugar_gtk2

    sys.modules["sugar"] = sugar_gtk2

* The result is that all unported/unmodified activities (without the GTK3_PORTED file) would <tt>import sugar.foo</tt> as before, but the above trick that modifies Python's module table would result in them (transparently, magically, automatically) being redirected to sugar_gtk2.foo.

* At the end of the transition period, sugar_gtk2 would be deleted in entirity, the above addition to sugar-activity would be dropped, and activities could drop the GTK3_PORTED files at their leisure.

Further consideration must be given to sugar-base. This package installs some classes which are then used by sugar-toolkit, so they would need to be duplicated into sugar_gtk2. This may be a good opportunity to consider merging sugar-base with sugar-toolkit.

The removal of the GTK2 sugar-toolkit version would happen one year after the first stable release of a sugar-toolkit that includes GTK3 support. In this context, 'removal' means that it gets deleted from the sugar-toolkit master branch of the git tree. Old versions of sugar-toolkit will of course be left available, in old git branches and release tarballs.

=== Proposed plan of action ===

=== Proposed plan of action ===

The steps below prioritise the porting of sugar-toolkit, as this is where Sugar would see the most immediate benefit: the revival of Browse and Read. The steps that follow can largely be parallelised.

The steps below prioritise the porting of sugar-toolkit, as this is where Sugar would see the most immediate benefit: the revival of Browse and Read. The steps that follow can largely be parallelised; the important bit is placing sugar-toolkit first in line.

# Remove hippocanvas from sugar-toolkit

# Remove hippocanvas from sugar-toolkit

# Port sugar-toolkit to GTK3 while keeping backwards compatibility

# Port sugar-toolkit to GTK3 while keeping backwards compatibility, release as sugar-toolkit-0.95.x

# Rescue Browse and Read, and allow independent activity porting efforts to begin

# Rescue Browse and Read, and allow independent activity porting efforts to begin

# Remove hippocanvas from all other parts of Sugar, including activities

# Remove hippocanvas from all other parts of Sugar, including activities

# Port Sugar core to GTK3

# Port Sugar core to GTK3

# Some time later, remove sugar-toolkit's GTK2 compatibility.

# Remove sugar-toolkit's GTK2 compatibility one year after the first GTK3 sugar-toolkit stable release

#* I propose that this happens 1 year after release of the first sugar-toolkit GTK3 version

=== How to port ===

=== How to port ===

The migration of sugar-toolkit, sugar, datastore, etc, is likely to take more than 1 release cycle, but the above scheme can still apply. When each component is ported to GTK3, it would then pick up the 1.0 tag. For example, the first major release that includes any GTK3 may well include sugar-toolkit-1.0 (GTK3 ported) alongside sugar-datastore-0.96 (not yet ported).

The migration of sugar-toolkit, sugar, datastore, etc, is likely to take more than 1 release cycle, but the above scheme can still apply. When each component is ported to GTK3, it would then pick up the 1.0 tag. For example, the first major release that includes any GTK3 may well include sugar-toolkit-1.0 (GTK3 ported) alongside sugar-datastore-0.96 (not yet ported).

=== Python 3 ===

=== Python 3 ===