Hi, I recently realised one can use immutable default arguments to avoid a chain of:
def append_to(element, to=None):
if to is None:
to = []
at the beginning of each function with default argument for set, list, or dict.
This is the way you’re supposed to write it in Python.
It is something you get used to, yet I think it’s sad.
You can use mutable default arguments now with a new syntax:
https://peps.python.org/pep-0671/
def bisect_right(a, x, lo=0, hi=>len(a), *, key=None): def connect(timeout=>default_timeout): def add_item(item, target=>[]): def format_time(fmt, time_t=>time.time()):Oh wow! This would be great I really hope it’s accepted and implemented, makes a lot of sense!
This is only a Draft for now though
Does not seems to work on 3.12:
Python 3.12.11 (main, Jun 29 2025, 16:18:35) [MSC v.1944 64 bit (AMD64)] on win32 >>> def toto(tata=>[]): File "<stdin>", line 1 def toto(tata=>[]): ^ SyntaxError: invalid syntaxUpvote for the sanity check.
As the OP mentioned, this is a proposed/draft feature that may or may not ever happen.
With these kinda posts, should start a betting pool. To put money down on whether this feature sees the light of day within an agreed upon fixed time frame.
Thank you
Yeah, but you can also write it like I proposed which is less boilerplaty and gives the same advantages
