[Python-checkins] python/dist/src/Doc/lib libweakref.tex,1.17,1.18

[rhettinger@users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory usw-pr-cvs1:/tmp/cvs-serv19689

Modified Files:
	libweakref.tex 
Log Message:
Described responsibilty of weakly referenced extension types to initialize
the weakreflist to NULL in the constructor and to fill the tp_flags
slot with Py_TPFLAGS_HAVE_WEAKREFS.  Closes SF bug 586583.


Index: libweakref.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libweakref.tex,v
retrieving revision 1.17
retrieving revision 1.18
diff -C2 -d -r1.17 -r1.18
*** libweakref.tex	8 Dec 2001 18:02:49 -0000	1.17
--- libweakref.tex	7 Aug 2002 16:18:54 -0000	1.18
***************
*** 218,222 ****
  object's constructor.  It must also set the \member{tp_weaklistoffset}
  field of the corresponding type object to the offset of the field.
! For example, the instance type is defined with the following structure:
  
  \begin{verbatim}
--- 218,224 ----
  object's constructor.  It must also set the \member{tp_weaklistoffset}
  field of the corresponding type object to the offset of the field.
! Also, it needs to add \constant{Py_TPFLAGS_HAVE_WEAKREFS} to the
! tp_flags slot.  For example, the instance type is defined with the
! following structure:
  
  \begin{verbatim}
***************
*** 239,244 ****
      /* Lots of stuff omitted for brevity... */
  
!     offsetof(PyInstanceObject, in_weakreflist) /* tp_weaklistoffset */
  };
  \end{verbatim}
  
--- 241,265 ----
      /* Lots of stuff omitted for brevity... */
  
!     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_WEAKREFS   /* tp_flags */
!     0,                                          /* tp_doc */
!     0,                                          /* tp_traverse */
!     0,                                          /* tp_clear */
!     0,                                          /* tp_richcompare */
!     offsetof(PyInstanceObject, in_weakreflist), /* tp_weaklistoffset */
  };
+ \end{verbatim}
+ 
+ The type constructor is responsible for initializing the weak reference
+ list to \NULL:
+ 
+ \begin{verbatim}
+ static PyObject * 
+ instance_new() { 
+     /* Other initialization stuff omitted for brevity */ 
+ 
+     self->in_weakreflist = NULL; 
+ 
+     return (PyObject *) self; 
+ } 
  \end{verbatim}