Brett Cannon: A reverse chronology of some Python features

I occasionally hear people lament that Python is "bloated", "too big", "going enterprise", or some other phrasing to suggest there was once an "ideal" version of Python that had less bloat and was closer to what the person wanted.

But then this lament is also often followed by, "but I would want this one feature from a newer version of Python". 🤨 What I think a lot of people don&apost realize is that various features are interconnected in ways that may not be obvious. And this can go beyond the typical cause-and-effect scenario where you can&apost cleanly separate inspiration, etc. from each other.

Take, for instance, pattern matching. Plenty of people complained that it wasn&apost going to be necessary and they could live without it. But the adding of pattern matching necessitated writing a new parser for Python. That new parser allowed for improved error messages (something I have yet to hear anyone say was a bad thing to introduce and for a lot of people their favourite feature in Python 3.10). So if you don&apost want the match statement, are you willing to give up the better error messages as a trade?

To help those who wish for the "good old days" of some older Python version, I thought I would write down a bunch of the major language features that were added in Python in reverse chronological order. Start from top and work your way down until you come across a feature you aren&apost willing to give up. The Python version which has that feature is the version you would be okay going back to.

By the way, you also have to give up all subsequent performance improvements when you go back as new features lead to code clean up, new insights on how to make something better, etc. And I can tell you right now, if you like performance you are probably going to be making Python 3.11 your favourite version of Python. 😁

• Python 3.10 (2021-10-04)
  • Parenthesized context managers
  • Better error messages
  • match statement
  • Union operator for types (str | bytes)
• 3.9 (2020-10-05)
  • Dictionary support for | and |=
  • str.removeprefix() and str.removesuffix()
  • Type hinting generics for the built-in collections (list[int])
• 3.8 (2019-10-14)
  • Assignment expressions (:=)
  • Positional-only parameters (def func(x, /): ...)
  • f-string support for = (f"{val=}")
• 3.7 (2018-06-27)
  • from __future__ import annotations
  • breakpoint()
  • Show deprecations in __main__
  • Generic types (__class_getitem__() and __mro_entries__)
  • Dictionaries preserve insertion order
• 3.6 (2016-12-23)
  • f-strings (f"{yes}!")
  • Variable annotations (var : int)
  • Underscores in numeric literals (1_000_000)
  • Asynchronous generators (await in async def)
  • Asynchronous comprehensions ([i async for i in aiter() if i % 2])
  • __init_subclass__()
  • __set_name__() for descriptors
  • __fspath__()
  • Preserving class attribute definition order
  • Preserving keyword argument order
• 3.5 (2015-09-13)
  • async and await
  • @ infix operator for matrix multiplication
  • Multiple iterable unpacking simultaneously (print(*[1], *[2], 3, *[4, 5]))
  • Interpolation support for bytes and bytearray via %
  • Type hints for function parameters
  • Change how StopIteration is handled in generators
• 3.4 (2013-08-03)
  • __spec__
• 3.3 (2012-09-29)
  • Virtual environments
  • Implicit namespace packages
  • yield from
  • Suppressing exception context (raise exc from None)
  • __qualname__
  • Import system moved to importlib
• 3.2 (2011-02-20)
• 3.1 (2009-06-27)
  • Thousands separator for str.format()

I&aposm going to stop at Python 3.1 because Python 3.0 is intertwined with Python 2.6 and the list is way too long to want to write out. And I&aposm not going past Python 3.0 because it&aposs time to move on already. 😁

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