此AttributeError消息在CPython中在哪里实现? [英] Where is this AttributeError message implemented in CPython?

问题描述

我认为此Python会话中的 AttributeError 消息

I think that the AttributeError message in this Python session

>>> class A: pass
... 
>>> A().x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'x'

在_PyObject_GenericGetAttrWithDict 中实现.rel ="nofollow noreferrer">在CPython中这些行:

is implemented in the function _PyObject_GenericGetAttrWithDict at these lines in CPython:

    if (!suppress) {
        PyErr_Format(PyExc_AttributeError,
                     "'%.50s' object has no attribute '%U'",
                     tp->tp_name, name);
    }

但是我找不到此Python会话中 AttributeError 消息的位置

However I cannot find where the AttributeError message in this Python session

>>> class A: __slots__ = ('x',)
... 
>>> A().x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: x

在CPython中实现.您能否提供指向GitHub存储库中确切行的链接?

is implemented in CPython. Could you provide a link to the exact lines in the GitHub repository?

推荐答案

它是此处:

case T_OBJECT_EX:
    v = *(PyObject **)addr;
    if (v == NULL)
        PyErr_SetString(PyExc_AttributeError, l->name);
    Py_XINCREF(v);
    break;

那是 PyMember_GetOne 的摘录，这是

That's an excerpt from PyMember_GetOne, which is where most of the logic for the __get__ method of the slot descriptor is implemented.

您可能还对该描述符如何到达那里感兴趣.内部 type .__ new __ 将 __ slots __ 转换为生成基于 PyMemberDef 数组的广告位描述符.

You might also be interested in how that descriptor gets there. type.__new__ internally translates __slots__ to an array of PyMemberDef structs, one of the mechanisms classes written in C use to define access to their internal data. All PyMemberDef structs generated this way are marked T_OBJECT_EX, meaning they correspond to a PyObject * in the instance memory layout, and if the pointer is null, access should raise an AttributeError. PyType_Ready then generates the slot descriptors based on the PyMemberDef array.

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