On Thu, Apr 28, 2022 at 4:15 PM Ethan Furman <ethan@stoneleaf.us> wrote:
NOTE: another key question for this proposal is how you would handle mutable defaults -- anything special, or "don't do that"?
Why should they be handled at all? If the programmer writes
def __init__(a, @b, @c=[]): pass
then all instances that didn't have `c` given will share the same list -- just like if the code was:
def __init__(a, b, c=[]): self.b = b self.c = c
so the answer is "don't do that" (unless, in the rare case, that's what you actually want). The purpose of the syntax is to automatically save arguments to same-named
attributes, not to perform any other magic.
If the programmer writes
def __init__(a, @b, @c=[]): pass sure but that's the coon case -- more common would be: def __init__(a, @b, c=None): handle_a if c is None: c = [] or some such. so without "any other magic", then we have a less useful proposal. One thing you can say about dataclasses is that they provide a way to handle all parameters, mutable and immutable. Anyway, I just thought it should be clearly said. -CHB -- Christopher Barker, PhD (Chris) Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython