You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
68 lines
1.6 KiB
68 lines
1.6 KiB
5 years ago
|
r'''
|
||
|
This tests the '_objects' attribute of ctypes instances. '_objects'
|
||
|
holds references to objects that must be kept alive as long as the
|
||
|
ctypes instance, to make sure that the memory buffer is valid.
|
||
|
|
||
|
WARNING: The '_objects' attribute is exposed ONLY for debugging ctypes itself,
|
||
|
it MUST NEVER BE MODIFIED!
|
||
|
|
||
|
'_objects' is initialized to a dictionary on first use, before that it
|
||
|
is None.
|
||
|
|
||
|
Here is an array of string pointers:
|
||
|
|
||
|
>>> from ctypes import *
|
||
|
>>> array = (c_char_p * 5)()
|
||
|
>>> print(array._objects)
|
||
|
None
|
||
|
>>>
|
||
|
|
||
|
The memory block stores pointers to strings, and the strings itself
|
||
|
assigned from Python must be kept.
|
||
|
|
||
|
>>> array[4] = b'foo bar'
|
||
|
>>> array._objects
|
||
|
{'4': b'foo bar'}
|
||
|
>>> array[4]
|
||
|
b'foo bar'
|
||
|
>>>
|
||
|
|
||
|
It gets more complicated when the ctypes instance itself is contained
|
||
|
in a 'base' object.
|
||
|
|
||
|
>>> class X(Structure):
|
||
|
... _fields_ = [("x", c_int), ("y", c_int), ("array", c_char_p * 5)]
|
||
|
...
|
||
|
>>> x = X()
|
||
|
>>> print(x._objects)
|
||
|
None
|
||
|
>>>
|
||
|
|
||
|
The'array' attribute of the 'x' object shares part of the memory buffer
|
||
|
of 'x' ('_b_base_' is either None, or the root object owning the memory block):
|
||
|
|
||
|
>>> print(x.array._b_base_) # doctest: +ELLIPSIS
|
||
|
<ctypes.test.test_objects.X object at 0x...>
|
||
|
>>>
|
||
|
|
||
|
>>> x.array[0] = b'spam spam spam'
|
||
|
>>> x._objects
|
||
|
{'0:2': b'spam spam spam'}
|
||
|
>>> x.array._b_base_._objects
|
||
|
{'0:2': b'spam spam spam'}
|
||
|
>>>
|
||
|
|
||
|
'''
|
||
|
|
||
|
import unittest, doctest
|
||
|
|
||
|
import ctypes.test.test_objects
|
||
|
|
||
|
class TestCase(unittest.TestCase):
|
||
|
def test(self):
|
||
|
failures, tests = doctest.testmod(ctypes.test.test_objects)
|
||
|
self.assertFalse(failures, 'doctests failed, see output above')
|
||
|
|
||
|
if __name__ == '__main__':
|
||
|
doctest.testmod(ctypes.test.test_objects)
|