Deprecate the tuple API (`object[index]`) of structseq types (ex: os.stat_result)

[vstinner]

Hi,

I propose deprecating the tuple API (object[index]) of the following structseq objects:

• _interpchannels.ChannelInfo
• _lsprof.profiler_entry
• _lsprof.profiler_subentry
• _thread._ExceptHookArgs
• grp.struct_group
• os.sched_param
• os.stat_result
• os.statvfs_result
• os.terminal_size
• os.times_result
• os.uname_result
• os.waitid_result
• pwd.struct_passwd
• resource.struct_rusage
• signal.struct_siginfo
• sys.UnraisableHookArgs
• sys._emscripten_info
• sys.asyncgen_hooks
• sys.flags
• sys.float_info
• sys.getwindowsversion
• sys.hash_info
• sys.int_info

The tuple API of the following structseq objects is kept, since it's useful:

• sys.version_info: for example, sys.version_info[:2] is commonly used.
• curses.ncurses_version: same rationale than sys.version_info.
• time.struct_time: for example, y, m, d, hh, mm, ss = struct_time[:6] is used to unpack a time struct.

---

In the early days of Python, it was tedious to create an object with attributes in C. So to keep the implementation simple, many functions returned simply a tuple (trivial to build in C). Example on Python 1.5 (yes, Python version one!):

$ ./python
Python 1.5.2 (#1, Aug  7 2026, 17:03:12)  [GCC 16.1.1 20260515 (Red Hat 16.1.1-2) on linux7
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> import os
>>> st=os.stat(".")
>>> type(st)
<type 'tuple'>
>>> st
(16877, 60670004, 43, 1, 1000, 1000, 476, 1786114992, 1786114992, 1786114992)

The stat module provides indices to state struct members:

# Indices for stat struct members in the tuple returned by os.stat()

ST_MODE  = 0
ST_INO   = 1
ST_DEV   = 2
ST_NLINK = 3
ST_UID   = 4
ST_GID   = 5
ST_SIZE  = 6
ST_ATIME = 7
ST_MTIME = 8
ST_CTIME = 9

For example, st[stat.ST_INO] gets the inode number.

---

Over time, APIs became more and more complex and the structseq type was added to Python 2.2. It preserves the tuple API (object[index]), but adds also named attributes to object.

For example, st.st_ino gets the inode number. The tuple API is kept for backward compatibility.

os.stat_result has a complex history:

• At the beginning, os.stat() simply returned a tuple of 10 integers.
• Python 2.2 changed os.stat() result type to os.stat_result to give access to attribute by name, but keep the tuple API for backward compatibility.
• Python 2.3 added os.stat_float_times(True) which allowed to get timestamps as float: timestamps remain integers by default. Only st.st_atime, st.st_ctime and st.st_mtime can be float. st[7], st[8] and st[9] are always integers, for backward compatibility.
• Python 2.5 switched timestamps to float by default.
• Python 3.3 added st_atime_ns, st_ctime_ns and st_mtime_ns.

So timestamps are stored in 3 formats in Python 3.15:

• integer (tuple API: seconds) for backward compatibility with Python 2.2 and older (yep, that's quite old!);
• float for st_[acm]time (seconds);
• integer for st_[acm]time_ns (nanoseconds).

I would prefer to deprecate this tuple API. It's time to move on to named attributes introduced in Python 2.3!

---

Last years, new structseq objects were added with the tuple API even if these new objects didn't have to provide a backward compatibility with a previous tuple API. It's just because structseq doesn't give the choice, the tuple API is always provided.

---

By the way, later, _PyNamespace_New() and types.SimpleNamespace were added to Python 3.3 to create a simple object with attributes from a dictionary (attribute name => attribute value). For example, sys.implementation uses this API.

Linked PRs

• gh-155358: [WIP] Deprecate tuple API of structseq objects #155359
• gh-155358: Use named attributes with pwd and grp modules #155362
• gh-155358: Use named attributes with urllib.parse module #155364
• gh-155358: Use named attributes with os module #155366
• gh-155358: Use named attributes with test.support.script_helper #155367
• gh-155358: Convert sys structseq types to heap types #155368

[vstinner]

I created a discussion for this change: https://discuss.python.org/t/deprecate-the-tuple-api-object-index-of-structseq-objects-like-os-stat-result/108464.