ctypes Stucture._fields_ cannot be set when Structure has been subclassed #100980
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Bug report
Currently the method for defining Structure fields that cannot be defined within the class, is to define the class with pass and then set _fields_ outside. But ctypes.Structure incorrectly raises AttributeError, even when no class has ever set a _fields_.
from ctypes import *
class PyObject(Structure):
pass
class PyVarObject(PyObject):
pass
class PyTypeObject(PyVarObject):
pass
PyObject._fields_ = [
("ob_refcnt", c_long),
("ob_type", POINTER(PyTypeObject)),
] PyObject._fields_ = [
^^^^^^^^^^^^^^^^^
AttributeError: _fields_ is finalStrangely, suppressing this Attribute error reveals the _fields_ attribute does actually get set?
with suppress(AttributeError):
PyObject._fields_ = [
("ob_refcnt", c_long),
("ob_type", POINTER(PyTypeObject)),
]
print(PyObject._fields_)
>> [('ob_refcnt', <class 'ctypes.c_long'>), ('ob_type', <class '__main__.LP_PyTypeObject'>)]Your environment
- CPython versions tested on: 3.11.1, main
- Operating system and architecture: macOS ARM, ubuntu x64
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