diff options
author | Jeroen Ruigrok van der Werven <asmodai@in-nomine.org> | 2009-04-26 21:06:15 (GMT) |
---|---|---|
committer | Jeroen Ruigrok van der Werven <asmodai@in-nomine.org> | 2009-04-26 21:06:15 (GMT) |
commit | bd87552a3453539f2a70f2b7c50c2980a436c567 (patch) | |
tree | 4b505dd36616aa61eb6e67c6fa965e3aee07b28d /Doc/c-api/gcsupport.rst | |
parent | 939c178379c6d979f49a083a6f3cbabf7b10b479 (diff) | |
download | cpython-bd87552a3453539f2a70f2b7c50c2980a436c567.zip cpython-bd87552a3453539f2a70f2b7c50c2980a436c567.tar.gz cpython-bd87552a3453539f2a70f2b7c50c2980a436c567.tar.bz2 |
Merged revisions 71898-71900,71910,71914-71919 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r71898 | jeroen.ruigrok | 2009-04-25 16:24:30 +0200 (za, 25 apr 2009) | 2 lines
Reformat prior to editing.
........
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.
........
r71900 | jeroen.ruigrok | 2009-04-25 16:28:02 +0200 (za, 25 apr 2009) | 2 lines
Reformat paragraph.
........
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.
........
r71914 | jeroen.ruigrok | 2009-04-25 20:31:20 +0200 (za, 25 apr 2009) | 2 lines
Reformat prior to editing.
........
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.
........
r71916 | jeroen.ruigrok | 2009-04-25 20:53:48 +0200 (za, 25 apr 2009) | 2 lines
Reformat prior to editing.
........
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.
........
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.
........
r71919 | jeroen.ruigrok | 2009-04-25 21:10:52 +0200 (za, 25 apr 2009) | 2 lines
Reformat prior to editing.
........
Diffstat (limited to 'Doc/c-api/gcsupport.rst')
-rw-r--r-- | Doc/c-api/gcsupport.rst | 74 |
1 files changed, 39 insertions, 35 deletions
diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst index fe2b0ca..dd75191 100644 --- a/Doc/c-api/gcsupport.rst +++ b/Doc/c-api/gcsupport.rst @@ -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. |