Misc/pymemcompat.h

   1 /* The idea of this file is that you bundle it with your extension,
   2    #include it, program to Python 2.3's memory API and have your
   3    extension build with any version of Python from 1.5.2 through to
   4    2.3 (and hopefully beyond). */
   5
   6 #ifndef Py_PYMEMCOMPAT_H
   7 #define Py_PYMEMCOMPAT_H
   8
   9 #include "Python.h"
  10
  11 /* There are three "families" of memory API: the "raw memory", "object
  12    memory" and "object" families.  (This is ignoring the matter of the
  13    cycle collector, about which more is said below).
  14
  15    Raw Memory:
  16
  17        PyMem_Malloc, PyMem_Realloc, PyMem_Free
  18
  19    Object Memory:
  20
  21        PyObject_Malloc, PyObject_Realloc, PyObject_Free
  22
  23    Object:
  24
  25        PyObject_New, PyObject_NewVar, PyObject_Del
  26
  27    The raw memory and object memory allocators both mimic the
  28    malloc/realloc/free interface from ANSI C, but the object memory
  29    allocator can (and, since 2.3, does by default) use a different
  30    allocation strategy biased towards lots of "small" allocations.
  31
  32    The object family is used for allocating Python objects, and the
  33    initializers take care of some basic initialization (setting the
  34    refcount to 1 and filling out the ob_type field) as well as having
  35    a somewhat different interface.
  36
  37    Do not mix the families!  E.g. do not allocate memory with
  38    PyMem_Malloc and free it with PyObject_Free.  You may get away with
  39    it quite a lot of the time, but there *are* scenarios where this
  40    will break.  You Have Been Warned.
  41
  42    Also, in many versions of Python there are an insane amount of
  43    memory interfaces to choose from.  Use the ones described above. */
  44
  45 #if PY_VERSION_HEX < 0x01060000
  46 /* raw memory interface already present */
  47
  48 /* there is no object memory interface in 1.5.2 */
  49 #define PyObject_Malloc         PyMem_Malloc
  50 #define PyObject_Realloc        PyMem_Realloc
  51 #define PyObject_Free           PyMem_Free
  52
  53 /* the object interface is there, but the names have changed */
  54 #define PyObject_New            PyObject_NEW
  55 #define PyObject_NewVar         PyObject_NEW_VAR
  56 #define PyObject_Del            PyMem_Free
  57 #endif
  58
  59 /* If your object is a container you probably want to support the
  60    cycle collector, which was new in Python 2.0.
  61
  62    Unfortunately, the interface to the collector that was present in
  63    Python 2.0 and 2.1 proved to be tricky to use, and so changed in
  64    2.2 -- in a way that can't easily be papered over with macros.
  65
  66    This file contains macros that let you program to the 2.2 GC API.
  67    Your module will compile against any Python since version 1.5.2,
  68    but the type will only participate in the GC in versions 2.2 and
  69    up.  Some work is still necessary on your part to only fill out the
  70    tp_traverse and tp_clear fields when they exist and set tp_flags
  71    appropriately.
  72
  73    It is possible to support both the 2.0 and 2.2 GC APIs, but it's
  74    not pretty and this comment block is too narrow to contain a
  75    desciption of what's required... */
  76
  77 #if PY_VERSION_HEX < 0x020200B1
  78 #define PyObject_GC_New         PyObject_New
  79 #define PyObject_GC_NewVar      PyObject_NewVar
  80 #define PyObject_GC_Del         PyObject_Del
  81 #define PyObject_GC_Track(op)
  82 #define PyObject_GC_UnTrack(op)
  83 #endif
  84
  85 #endif /* !Py_PYMEMCOMPAT_H */