1 cdef extern from "Python.h": 2 ctypedef struct PyTypeObject 3 ctypedef struct PyObject: 4 Py_ssize_t ob_refcnt 5 PyTypeObject *ob_type 6 cdef PyTypeObject *Py_TYPE(object) 7 8 9 ##################################################################### 10 # 3. Reference Counts 11 ##################################################################### 12 # The macros in this section are used for managing reference counts of Python objects. 13 void Py_INCREF(object o) 14 # Increment the reference count for object o. The object must not 15 # be NULL; if you aren't sure that it isn't NULL, use 16 # Py_XINCREF(). 17 18 void Py_XINCREF(PyObject* o) 19 # Increment the reference count for object o. The object may be NULL, in which case the macro has no effect. 20 21 void Py_DECREF(object o) 22 # Decrement the reference count for object o. The object must not 23 # be NULL; if you aren't sure that it isn't NULL, use 24 # Py_XDECREF(). If the reference count reaches zero, the object's 25 # type's deallocation function (which must not be NULL) is 26 # invoked. 27 28 # Warning: The deallocation function can cause arbitrary Python 29 # code to be invoked (e.g. when a class instance with a __del__() 30 # method is deallocated). While exceptions in such code are not 31 # propagated, the executed code has free access to all Python 32 # global variables. This means that any object that is reachable 33 # from a global variable should be in a consistent state before 34 # Py_DECREF() is invoked. For example, code to delete an object 35 # from a list should copy a reference to the deleted object in a 36 # temporary variable, update the list data structure, and then 37 # call Py_DECREF() for the temporary variable. 38 39 void Py_XDECREF(PyObject* o) 40 # Decrement the reference count for object o. The object may be 41 # NULL, in which case the macro has no effect; otherwise the 42 # effect is the same as for Py_DECREF(), and the same warning 43 # applies. 44 45 void Py_CLEAR(PyObject* o) 46 # Decrement the reference count for object o. The object may be 47 # NULL, in which case the macro has no effect; otherwise the 48 # effect is the same as for Py_DECREF(), except that the argument 49 # is also set to NULL. The warning for Py_DECREF() does not apply 50 # with respect to the object passed because the macro carefully 51 # uses a temporary variable and sets the argument to NULL before 52 # decrementing its reference count. 53 # It is a good idea to use this macro whenever decrementing the 54 # value of a variable that might be traversed during garbage 55 # collection. 56 57
