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https://sourceware.org/git/binutils-gdb.git
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1c9bcee307
Python extension objects that support __dict__ must inherit from gdbpy_dict_wrapper, a wrapper class that stores the PyObject corresponding to the __dict__ attribute. Because this dictionary is not managed directly by Python, each extension objects must provide appropriate accessors so that attributes stored in __dict__ are looked up correctly. Currently, management of this dictionary is not centralized, and each Python extension object implements its own logic to create, access, and destroy it. A previous patch centralized the creation logic; this patch focuses on centralizing the access to the dictionary. It introduces two new macros: - gdbpy_dict_wrapper_cfg_dict_getter, which defines a getter for __dict__. - gdbpy_dict_wrapper_getsetattro, which sets tp_getattro and tp_setattro in PyTypeObject to gdb_py_generic_getattro and gdb_py_generic_setattro, respectively. These helpers already centralizes attribute access for Python extension objects having a __dict__. Note: this macro will eventually be removed once Python extension types are migrated to heap-allocated types. Approved-By: Tom Tromey <tom@tromey.com>
105 lines
3.4 KiB
C++
105 lines
3.4 KiB
C++
/* Python reference-holding class
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Copyright (C) 2016-2026 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef GDB_PYTHON_PY_REF_H
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#define GDB_PYTHON_PY_REF_H
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#include "gdbsupport/gdb_ref_ptr.h"
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/* A policy class for gdb::ref_ptr for Python reference counting. */
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struct gdbpy_ref_policy
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{
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static void incref (PyObject *ptr)
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{
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Py_INCREF (ptr);
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}
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static void decref (PyObject *ptr)
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{
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Py_DECREF (ptr);
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}
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};
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/* A gdb::ref_ptr that has been specialized for Python objects or
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their "subclasses". */
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template<typename T = PyObject> using gdbpy_ref
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= gdb::ref_ptr<T, gdbpy_ref_policy>;
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/* A wrapper class for Python extension objects that have a __dict__ attribute.
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Any Python C object extension needing __dict__ should inherit from this
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class. Given that the C extension object must also be convertible to
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PyObject, this wrapper class publicly inherits from PyObject as well.
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Access to the dict requires a custom getter defined via PyGetSetDef.
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gdb_PyGetSetDef my_object_getset[] =
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{
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gdbpy_dict_wrapper_cfg_dict_getter ("object"),
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...
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{ nullptr }
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};
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It is also important to note that __dict__ is used during the attribute
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look-up. Since this dictionary is not managed by Python and is not exposed
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via tp_dictoffset, custom attribute getter (tp_getattro) and setter
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(tp_setattro) are required to correctly redirect attribute access to the
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dictionary:
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- gdb_py_generic_getattro (), assigned to tp_getattro for static types,
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or Py_tp_getattro for heap-allocated types.
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- gdb_py_generic_setattro (), assigned to tp_setattro for static types,
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or Py_tp_setattro for heap-allocated types. */
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struct gdbpy_dict_wrapper : public PyObject
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{
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/* Dictionary holding user-added attributes.
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This is the __dict__ attribute of the object. */
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PyObject *dict;
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/* Compute the address of the __dict__ attribute for the given PyObject. */
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static PyObject **compute_addr (PyObject *self)
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{
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auto *wrapper = reinterpret_cast<gdbpy_dict_wrapper *> (self);
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return &wrapper->dict;
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}
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#define gdbpy_dict_wrapper_cfg_dict_getter(object_name) \
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{ \
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"__dict__", /* name */ \
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(getter) gdb_py_generic_dict_getter, \
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(setter) nullptr, \
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"The __dict__ for this " object_name ".", /* doc */ \
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nullptr, /* closure */ \
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}
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#define gdbpy_dict_wrapper_getsetattro \
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/*tp_getattro*/ \
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gdb_py_generic_getattro, \
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/*tp_setattro*/ \
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gdb_py_generic_setattro
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/* Allocate the dictionary pointed by 'dict'.
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Note: this method should be called once the object was allocated,
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when setting its attributes. */
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bool allocate_dict ()
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{
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dict = PyDict_New ();
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return dict != nullptr;
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}
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};
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#endif /* GDB_PYTHON_PY_REF_H */
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