[Python-checkins] CVS: python/dist/src/Doc/lib libweakref.tex,1.14,1.15

2001年10月26日 10:40:24 -0700

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory usw-pr-cvs1:/tmp/cvs-serv6801/lib
Modified Files:
	libweakref.tex 
Log Message:
Many, many small fixes and improvements, most suggested by Detlef Lannert.
Index: libweakref.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libweakref.tex,v
retrieving revision 1.14
retrieving revision 1.15
diff -C2 -d -r1.14 -r1.15
*** libweakref.tex	2001年10月26日 11:27:54	1.14
--- libweakref.tex	2001年10月26日 17:40:22	1.15
***************
*** 15,18 ****
--- 15,21 ----
 \dfn{weak references} to objects.

+ In the discussion which follows, the term \dfn{referent} means the
+ object which is referred to by a weak reference.
+ 
 XXX --- need to say more here!

***************
*** 25,34 ****

 \begin{funcdesc}{ref}{object\optional{, callback}}
! Return a weak reference to \var{object}. If \var{callback} is
 provided, it will be called when the object is about to be
 finalized; the weak reference object will be passed as the only
 parameter to the callback; the referent will no longer be available.
- The original object can be retrieved by calling the reference
- object, if the referent is still alive.

 It is allowable for many weak references to be constructed for the
--- 28,38 ----

 \begin{funcdesc}{ref}{object\optional{, callback}}
! Return a weak reference to \var{object}. The original object can be
! retrieved by calling the reference object if the referent is still
! alive; if the referent is no longer alive, calling the reference
! object will cause \code{None} to be returned. If \var{callback} is
 provided, it will be called when the object is about to be
 finalized; the weak reference object will be passed as the only
 parameter to the callback; the referent will no longer be available.

 It is allowable for many weak references to be constructed for the
***************
*** 49,56 ****

 Weak references support tests for equality, but not ordering. If
! the \var{object} is still alive, two references are equal if the
! objects are equal (regardless of the \var{callback}). If
! \var{object} has been deleted, they are equal only if the references
! being compared are the same reference object.
 \end{funcdesc}

--- 53,61 ----

 Weak references support tests for equality, but not ordering. If
! the referents are still alive, two references have the same
! equalality relationship as their referents (regardless of the
! \var{callback}). If either referent has been deleted, the
! references are equal only if the reference objects are the same
! object.
 \end{funcdesc}

***************
*** 90,94 ****
 Mapping class that references values weakly. Entries in the
 dictionary will be discarded when no strong reference to the value
! exists anymore.
 \end{classdesc}

--- 95,99 ----
 Mapping class that references values weakly. Entries in the
 dictionary will be discarded when no strong reference to the value
! exists any more.
 \end{classdesc}

***************
*** 159,163 ****

 \begin{verbatim}
! o = ref()
 if o is None:
 # referent has been garbage collected
--- 164,169 ----

 \begin{verbatim}
! # r is a weak reference object
! o = r()
 if o is None:
 # referent has been garbage collected
***************
*** 170,174 ****
 Using a separate test for ``liveness'' creates race conditions in
 threaded applications; another thread can cause a weak reference to
! become invalidated before the \method{get()} method is called; the
 idiom shown above is safe in threaded applications as well as
 single-threaded applications.
--- 176,180 ----
 Using a separate test for ``liveness'' creates race conditions in
 threaded applications; another thread can cause a weak reference to
! become invalidated before the weak reference is called; the
 idiom shown above is safe in threaded applications as well as
 single-threaded applications.
***************
*** 190,197 ****

 def remember(obj):
! _id2obj_dict[id(obj)] = obj

! def id2obj(id):
! return _id2obj_dict(id)
 \end{verbatim}

--- 196,205 ----

 def remember(obj):
! oid = id(obj)
! _id2obj_dict[oid] = obj
! return oid

! def id2obj(oid):
! return _id2obj_dict[oid]
 \end{verbatim}

***************
*** 206,210 ****

 For an object to be weakly referencable, the extension must include a
! \ctype{PyObject *} field in the instance structure for the use of the
 weak reference mechanism; it must be initialized to \NULL{} by the
 object's constructor. It must also set the \member{tp_weaklistoffset}
--- 214,218 ----

 For an object to be weakly referencable, the extension must include a
! \ctype{PyObject*} field in the instance structure for the use of the
 weak reference mechanism; it must be initialized to \NULL{} by the
 object's constructor. It must also set the \member{tp_weaklistoffset}
***************
*** 237,241 ****
 The only further addition is that the destructor needs to call the
 weak reference manager to clear any weak references. This should be
! done before any other parts of the destruction have occurred:

 \begin{verbatim}
--- 245,250 ----
 The only further addition is that the destructor needs to call the
 weak reference manager to clear any weak references. This should be
! done before any other parts of the destruction have occurred, but is
! only required if the weak reference list is non-\NULL:

 \begin{verbatim}
***************
*** 243,251 ****
 instance_dealloc(PyInstanceObject *inst)
 {
! /* Allocate tempories if needed, but do not begin
 destruction just yet.
 */

! PyObject_ClearWeakRefs((PyObject *) inst);

 /* Proceed with object destruction normally. */
--- 252,261 ----
 instance_dealloc(PyInstanceObject *inst)
 {
! /* Allocate temporaries if needed, but do not begin
 destruction just yet.
 */

! if (inst->in_weakreflist != NULL)
! PyObject_ClearWeakRefs((PyObject *) inst);

 /* Proceed with object destruction normally. */