[Python-checkins] CVS: python/dist/src PLAN.txt,1.1.2.23,1.1.2.24

[Tim Peters]

Update of /cvsroot/python/python/dist/src
In directory usw-pr-cvs1:/tmp/cvs-serv7970/descr/dist/src

Modified Files:
      Tag: descr-branch
	PLAN.txt 
Log Message:
Add a "real" tp_new slot to dicts, in order to get dicts initialized
before use.  I'm certain I didn't do it correctly, but don't understand
what "correctly" entails, exactly.  See PLAN.txt for more details.
test_descr.py doesn't core dump anymore, but fails one line later with
a verify() failure.


Index: PLAN.txt
===================================================================
RCS file: /cvsroot/python/python/dist/src/Attic/PLAN.txt,v
retrieving revision 1.1.2.23
retrieving revision 1.1.2.24
diff -C2 -r1.1.2.23 -r1.1.2.24
*** PLAN.txt	2001/07/08 07:47:05	1.1.2.23
--- PLAN.txt	2001/07/08 19:16:30	1.1.2.24
***************
*** 268,272 ****
  he dies of frustration while wrestling with CVS <0.9 wink>).
  
! ------------------------------------------------------------------
  2001-07-07
  
--- 268,272 ----
  he dies of frustration while wrestling with CVS <0.9 wink>).
  
! ----------------------------------------------------------------------------
  2001-07-07
  
***************
*** 286,317 ****
            correct exact order <wink>).
  
!           Now dies with a memory error right after
!               Testing Python subclass of dict...
  
!           Small program that reproduces the problem:
!               class C(dictionary):
!                   def __init__(self):
!                       self['a'] = 1
! 
!               a = C()
! 
!           Gross cause:  The dictionary has not been initialized, i.e.
!           mp->ma_table is NULL when we get into lookdict_string.  But
!           mp->ma_table must never be NULL after the trunk dict rewrite (any
!           legit way of creating the dict will leave ma_table pointing to
!           the ma_smalltable member).
! 
!           Note:  We get into lookdict_string because insertdict forces
!           mp->ma_lookup to lookdict_string if mp->ma_lookup is NULL.  It
!           is in this case.  But that again says this object never went thru
!           dict initialization:  insertdict should really be asserting that
!           mp->ma_lookup is not NULL on entry!  The trunk version simply
!           assumes it's not NULL (it's impossible to create a dict object
!           with it NULL).
! 
!           Looks like Guido added this in descr-branch rev 2.80.2.6
!           of dictobject.c; but this form of casting cheat doesn't work
!           anymore on dicts.
! ------------------------------------------------------------------
  2001-07-06
  
--- 286,317 ----
            correct exact order <wink>).
  
!           A core dump was "fixed" (unsure about that!) via adding a
!           tp_new slot to dict objects, to ensure that they're initialized
!           before being used.
! 
!           Now dies with
!             File "../lib/test\test_descr.py", line 325, in pydicts
!                 verify(a1.state == 12)
!             AttributeError: 'dictionary' object has no attribute 'state'
! 
!           I don't understand what tp_new is supposed to do for dicts,
!           exactly.  PEP 253 says
! 
!           - If the base type defines tp_init as well as tp_new, its tp_new
!             should be inheritable: it should call the tp_alloc and the
!             tp_init of the type passed in as its first argument.
! 
!           The tp_new I added doesn't do that, mostly because I couldn't find
!           any code that already does that in order to fill in the fine
!           points.  PEP 253 also says tp_alloc has signature:
! 
!             PyObject *tp_alloc(PyTypeObject *type,
!                                PyObject *args,
!                                PyObject *kwds)
  
!           but in reality it appears to be this instead:
! 
!               typedef PyObject *(*allocfunc)(struct _typeobject *, int);
! ----------------------------------------------------------------------------
  2001-07-06