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  r71898 | jeroen.ruigrok | 2009-04-25 16:24:30 +0200 (za, 25 apr 2009) | 2 lines

  Reformat prior to editing.
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  r71899 | jeroen.ruigrok | 2009-04-25 16:27:00 +0200 (za, 25 apr 2009) | 3 lines

  The type for ppos has been Py_ssize_t since 2.5, reflect this in the
  documentation.
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  r71900 | jeroen.ruigrok | 2009-04-25 16:28:02 +0200 (za, 25 apr 2009) | 2 lines

  Reformat paragraph.
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  r71910 | jeroen.ruigrok | 2009-04-25 19:59:03 +0200 (za, 25 apr 2009) | 4 lines

  Issue #4129: Belatedly document which C API functions had their argument(s) or
  return type changed from int or int * to Py_ssize_t or Py_ssize_t * as this
  might cause problems on 64-bit platforms.
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  r71914 | jeroen.ruigrok | 2009-04-25 20:31:20 +0200 (za, 25 apr 2009) | 2 lines

  Reformat prior to editing.
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  r71915 | jeroen.ruigrok | 2009-04-25 20:46:03 +0200 (za, 25 apr 2009) | 2 lines

  Issue #4129: Document more int -> Py_ssize_t changes.
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  r71916 | jeroen.ruigrok | 2009-04-25 20:53:48 +0200 (za, 25 apr 2009) | 2 lines

  Reformat prior to editing.
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  r71917 | jeroen.ruigrok | 2009-04-25 20:57:32 +0200 (za, 25 apr 2009) | 2 lines

  Reference to an int type, whereas it's a Py_ssize_t as the synopsis states.
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  r71918 | jeroen.ruigrok | 2009-04-25 21:04:15 +0200 (za, 25 apr 2009) | 2 lines

  Since I edited this file, reformat for future edits.
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  r71919 | jeroen.ruigrok | 2009-04-25 21:10:52 +0200 (za, 25 apr 2009) | 2 lines

  Reformat prior to editing.
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This commit is contained in:
Jeroen Ruigrok van der Werven 2009-04-26 21:06:15 +00:00
parent 939c178379
commit bd87552a34
14 changed files with 312 additions and 156 deletions
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74
Doc/c-api/gcsupport.rst
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@ -9,7 +9,8 @@ Python's support for detecting and collecting garbage which involves circular
references requires support from object types which are "containers" for other
objects which may also be containers. Types which do not store references to
other objects, or which only store references to atomic types (such as numbers
or strings), do not need to provide any explicit support for garbage collection.
or strings), do not need to provide any explicit support for garbage
collection.
To create a container type, the :attr:`tp_flags` field of the type object must
include the :const:`Py_TPFLAGS_HAVE_GC` and provide an implementation of the
@ -20,13 +21,14 @@ include the :const:`Py_TPFLAGS_HAVE_GC` and provide an implementation of the
.. data:: Py_TPFLAGS_HAVE_GC
:noindex:
Objects with a type with this flag set must conform with the rules documented
here. For convenience these objects will be referred to as container objects.
Objects with a type with this flag set must conform with the rules
documented here. For convenience these objects will be referred to as
container objects.
Constructors for container types must conform to two rules:
#. The memory for the object must be allocated using :cfunc:`PyObject_GC_New` or
:cfunc:`PyObject_GC_VarNew`.
#. The memory for the object must be allocated using :cfunc:`PyObject_GC_New`
or :cfunc:`PyObject_GC_VarNew`.
#. Once all the fields which may contain references to other containers are
initialized, it must call :cfunc:`PyObject_GC_Track`.
@ -46,17 +48,17 @@ Constructors for container types must conform to two rules:
.. cfunction:: PyVarObject * PyObject_GC_Resize(PyVarObject *op, Py_ssize_t)
Resize an object allocated by :cfunc:`PyObject_NewVar`. Returns the resized
object or *NULL* on failure.
Resize an object allocated by :cfunc:`PyObject_NewVar`. Returns the
resized object or *NULL* on failure.
.. cfunction:: void PyObject_GC_Track(PyObject *op)
Adds the object *op* to the set of container objects tracked by the collector.
The collector can run at unexpected times so objects must be valid while being
tracked. This should be called once all the fields followed by the
:attr:`tp_traverse` handler become valid, usually near the end of the
constructor.
Adds the object *op* to the set of container objects tracked by the
collector. The collector can run at unexpected times so objects must be
valid while being tracked. This should be called once all the fields
followed by the :attr:`tp_traverse` handler become valid, usually near the
end of the constructor.
.. cfunction:: void _PyObject_GC_TRACK(PyObject *op)
@ -82,10 +84,10 @@ rules:
.. cfunction:: void PyObject_GC_UnTrack(void *op)
Remove the object *op* from the set of container objects tracked by the
collector. Note that :cfunc:`PyObject_GC_Track` can be called again on this
object to add it back to the set of tracked objects. The deallocator
(:attr:`tp_dealloc` handler) should call this for the object before any of the
fields used by the :attr:`tp_traverse` handler become invalid.
collector. Note that :cfunc:`PyObject_GC_Track` can be called again on
this object to add it back to the set of tracked objects. The deallocator
(:attr:`tp_dealloc` handler) should call this for the object before any of
the fields used by the :attr:`tp_traverse` handler become invalid.
.. cfunction:: void _PyObject_GC_UNTRACK(PyObject *op)
@ -98,11 +100,12 @@ The :attr:`tp_traverse` handler accepts a function parameter of this type:
.. ctype:: int (*visitproc)(PyObject *object, void *arg)
Type of the visitor function passed to the :attr:`tp_traverse` handler. The
function should be called with an object to traverse as *object* and the third
parameter to the :attr:`tp_traverse` handler as *arg*. The Python core uses
several visitor functions to implement cyclic garbage detection; it's not
expected that users will need to write their own visitor functions.
Type of the visitor function passed to the :attr:`tp_traverse` handler.
The function should be called with an object to traverse as *object* and
the third parameter to the :attr:`tp_traverse` handler as *arg*. The
Python core uses several visitor functions to implement cyclic garbage
detection; it's not expected that users will need to write their own
visitor functions.
The :attr:`tp_traverse` handler must have the following type:
@ -111,10 +114,10 @@ The :attr:`tp_traverse` handler must have the following type:
Traversal function for a container object. Implementations must call the
*visit* function for each object directly contained by *self*, with the
parameters to *visit* being the contained object and the *arg* value passed to
the handler. The *visit* function must not be called with a *NULL* object
argument. If *visit* returns a non-zero value that value should be returned
immediately.
parameters to *visit* being the contained object and the *arg* value passed
to the handler. The *visit* function must not be called with a *NULL*
object argument. If *visit* returns a non-zero value that value should be
returned immediately.
To simplify writing :attr:`tp_traverse` handlers, a :cfunc:`Py_VISIT` macro is
provided. In order to use this macro, the :attr:`tp_traverse` implementation
@ -123,9 +126,9 @@ must name its arguments exactly *visit* and *arg*:
.. cfunction:: void Py_VISIT(PyObject *o)
Call the *visit* callback, with arguments *o* and *arg*. If *visit* returns a
non-zero value, then return it. Using this macro, :attr:`tp_traverse` handlers
look like::
Call the *visit* callback, with arguments *o* and *arg*. If *visit* returns
a non-zero value, then return it. Using this macro, :attr:`tp_traverse`
handlers look like::
static int
my_traverse(Noddy *self, visitproc visit, void *arg)
@ -135,14 +138,15 @@ must name its arguments exactly *visit* and *arg*:
return 0;
}
The :attr:`tp_clear` handler must be of the :ctype:`inquiry` type, or *NULL* if
the object is immutable.
The :attr:`tp_clear` handler must be of the :ctype:`inquiry` type, or *NULL*
if the object is immutable.
.. ctype:: int (*inquiry)(PyObject *self)
Drop references that may have created reference cycles. Immutable objects do
not have to define this method since they can never directly create reference
cycles. Note that the object must still be valid after calling this method
(don't just call :cfunc:`Py_DECREF` on a reference). The collector will call
this method if it detects that this object is involved in a reference cycle.
Drop references that may have created reference cycles. Immutable objects
do not have to define this method since they can never directly create
reference cycles. Note that the object must still be valid after calling
this method (don't just call :cfunc:`Py_DECREF` on a reference). The
collector will call this method if it detects that this object is involved
in a reference cycle.