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"""
Check that the @cython.no_gc_clear decorator disables generation of the
tp_clear slot so that __dealloc__ will still see the original reference
contents.
Discussed here: http://article.gmane.org/gmane.comp.python.cython.devel/14986
"""
cimport cython
from cpython.ref cimport PyObject, Py_TYPE
# Pull tp_clear for PyTypeObject as I did not find another way to access it
# from Cython code.
cdef extern from *:
ctypedef struct PyTypeObject:
void (*tp_clear)(object)
ctypedef struct __pyx_CyFunctionObject:
PyObject* func_closure
def is_tp_clear_null(obj):
return (<PyTypeObject*>Py_TYPE(obj)).tp_clear is NULL
def is_closure_tp_clear_null(func):
return is_tp_clear_null(
<object>(<__pyx_CyFunctionObject*>func).func_closure)
@cython.no_gc_clear
cdef class DisableTpClear:
"""
An extension type that has a tp_clear method generated to test that it
actually clears the references to NULL.
>>> uut = DisableTpClear()
>>> is_tp_clear_null(uut)
True
>>> uut.call_tp_clear()
>>> type(uut.requires_cleanup) == list
True
>>> del uut
"""
cdef public object requires_cleanup
def __cinit__(self):
self.requires_cleanup = [
"Some object that needs cleaning in __dealloc__"]
def call_tp_clear(self):
cdef PyTypeObject *pto = Py_TYPE(self)
if pto.tp_clear != NULL:
pto.tp_clear(self)
cdef class ReallowTpClear(DisableTpClear):
"""
>>> import gc
>>> obj = ReallowTpClear()
>>> is_tp_clear_null(obj)
False
>>> obj.attr = obj # create hard reference cycle
>>> del obj; _ignore = gc.collect()
# Problem: cannot really validate that the cycle was cleaned up without using weakrefs etc...
"""
cdef public object attr
def test_closure_without_clear(str x):
"""
>>> c = test_closure_without_clear('abc')
>>> is_tp_clear_null(c)
False
>>> is_closure_tp_clear_null(c)
True
>>> c('cba')
'abcxyzcba'
"""
def c(str s):
return x + 'xyz' + s
return c
def test_closure_with_clear(list x):
"""
>>> c = test_closure_with_clear(list('abc'))
>>> is_tp_clear_null(c)
False
>>> is_closure_tp_clear_null(c)
False
>>> c('cba')
'abcxyzcba'
"""
def c(str s):
return ''.join(x) + 'xyz' + s
return c
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