[pypy-dev] Summary of Leysin Sprint

[Samuele Pedroni]

Hello,

This is a summary of what was accomplished and worked on during last sprint
in Leysin.  Leysin is a village in the Swiss Alps, home to Armin Rigo.  The
views of the surrounding mountains were spectacular.  It seemed to 
inspire us
to work harder.  Thanks to Armin for organizing it:

* All project participants met and worked together for the first time.
  We introduced newcomers to the project to the PyPy code base and the
  development process.  We gave introductions to the basic functioning
  and the structure of the code base.  py.test our unit testing
  framework was introduced to those who hadn't seen it before.

* We also got to know our Process Manager, Bea Düring from
  Changemaker.  Bea will produce her own report.  If you don't know
  the difference between 'project management', 'people management',
  and 'process management' then you probably would enjoy learning the
  differences from Bea.  Bea interviewed the sprint participants to
  find out about their expectations, dissemination and more general
  ideas about the PyPy project and where it should go in the future.
  This Sprint went extremely well, but future ones should go even
  better, since we are learning how to improve all the time.  Bea is
  making a report that discusses this more.

* We made plans for new and improved infrastructure. Thank you svn, we
  can change our repository layout whenever we feel it would be a good
  idea.  :-)

But as for technical changes to pypy itself:

* The flow object space now uses variable names derived from the
  original python ones and propagate them as possible. (Armin, Olivier
  Dormond)

* The typedunwrap branch has been merged back to the trunk. (Armin,
  Samuele)

  Type specific unwraps (int_w, str_w, ...) should be used everywhere
  possible. The type generic unwrap should be used only in tests, at
  bootstrap time and or temporarily in cases where we are borrowing
  heavily from underlying CPython, because it is annotator unfriendly
  and is able to unwrap mixed types containers which are not
  reasonably RPythonic.
 
* Updated documentation to describe new type specific unwrap
  operations. (Michael, Samuele)

* We can now import and run the CPython tests on top of PyPy.  This
  found lots of small problems, and a few not so small ones.  So we
  made lots of small fixes, and implemented missing stuff, which was a
  good way for newcomers to get to know the codebase.  We added or
  completed functionality to sys module:
   
   - _getframe()
   - set/getrecursionlevel()
   - exc_clear() ...

  (Adrien Di Mascio, Anders Chrigström, Armin, Christian, Holger,
   Jacek Generowicz, Ludovic Aubry, Olivier, Samuele, Laura)

* Work on the annotator:
   - SomeBuiltin.call

   - implemented annotation for some built-ins that were missing

   - SomeSlice support and annotating some ops involving them

   - iter built-in

   - dict methods support for SomeDict

   - preserve instance types when unifying with None

   - dict object dummy value is a W_Root subclass instance, so as not
     to confuse the annotator

   - taught the annotator how to deduce the type of e in

     try:
       ...
     except SomeException, e:
       ... <-- here   

   - removal of most *args call sites used in the multi-method slicing
     mechanism, like what was done for gateways. The annotator no longer
     chokes on such call sites.  :-)

   - wrote a small test case to show the remaining problems with the
     current setup of BuiltinCode and BuiltinFrame subclasses and the
     highly polymorphic BuiltinCode.func callable attribute.

  (Adrien, Michael, Samuele, some design discussion with Armin)

* Added shortcuts is_w(.,.) (= space.is_true(space.is_(.,.))),
  eq_w(.,.)  (= space.is_true(space.eq(.,.))) to base object
  space. (Adrien)

* Allow arguments to be named in the stdobjspace's type's methods.  As
  a first example, this enables list.sort(cmp=...). (Armin)

* Generated app-level exceptions module and from there using
  geninterplevel an interp-level module (in particular this circumvent
  bootstrap issues). (Christian)

  This implementation approach for built-in modules should be polished
  and generalized.

* Added python library as of 2.3.4 to our tree as
  dist/lib-python-2.3.4.  After discussion, it was agreed that this
  should be left unchanged and modules needing modifications should be
  copied to pypy/lib (renamed from appspace) and modified there, also
  new pypy-specific app-level modules should live there. That means
  that as general rule we should copy and borrow from this specific
  Python version, in the not too distant future we will switch to
  Python 2.4.

  Pypy specific modified or new app-level tests should go to
  pypy/lib/test2. (Holger)

  Work is needed on how those should be run, we would like to be able
  to run them both on PyPy and on CPython.

* py.test support for unittest and output-comparing tests has been
  added to dist/lib-python-2.3.4 (this is a special exception to the
  above rules), as conftest.py and pypy_unittest.py in
  dist/lib-python-2.3.4/test.  Look at conftest.py for details, there
  are lists of passing tests there (Anders, Holger)

* Work on our sio based file implementation. (Armin did a major
  rework)

* Support for __del__ on user-defined classes. For now borrowing
  functionality from underlying CPython. (Armin)

* Work has been started on an app-level implementation for old-style
  classes, we have a good chunk of the implementation but it is not
  that much tested nor integrated for now. (Christian, Samuele)

* Marcus Denker gave a presentation on Squeak, its continuations based
  web framework Seaside and Croquet. We discussed whether PyPy is a
  sensible approach to give in the future comprehensive Python support
  as scripting language to Squeak/Croquet.

* We set tasks for the next few weeks, and now begin to prepare for the
  next Sprint, before PyCon.

regards.
Samuele and Laura


PS: I (Samuele) did the listing of tech changes, sorry if I missed 
someone's credits.