Minor change to LOAD_ATTR Opcode in 3.13 not documented

Documentation

The order that items are pushed to the stack by LOAD_ATTR changed in 3.13, but this is not mentioned in the dis module documentation for the LOAD_ATTR Opcode.

Further Details

For the LOAD_ATTR Opcode, the following change from 3.12 is documented

Changed in version 3.12: If the low bit of namei is set, then a NULL or self is pushed to the stack before the attribute or unbound method respectively.

And this can be seen in frameobject.c: https://github.com/python/cpython/blob/3.12/Objects/frameobject.c#L422 where NULL is pushed before Object.

However, in 3.13 this has changed, presumably due to changes to the CALL Opcode;

Changed in version 3.13: The callable now always appears at the same position on the stack.

And for LOAD_ATTR the NULL is now pushed to the stack after the attribute or unbound method.

This ordering change can be seen in frameobject.c for 3.13: https://github.com/python/cpython/blob/3.13/Objects/frameobject.c#L1280 where Object is now pushed before NULL.

Suggested Resolution

My suggestion would be adding something like this to the LOAD_ATTR documentation;

Changed in version 3.13: When the low bit of namei is set, NULL or self is pushed to the stack after the attribute or unbound method respectively.

Linked PRs

• gh-138631

從 Python 3.13 dis 模組文件中的 LOAD_ATTR 項目開始，將其措辭與 issue 中連結的 3.12 和 3.13 frameobject.c 位置進行比較。在進行變更前檢查連結的 PR gh-138631；當 3.13 的堆疊順序變更被準確記錄後，文件工作就完成了。