I declare this post Off Topic. Please open another thread (preferably on python-ideas).

Everybody else, please don't respond to this particular post by the OP.

On Wed, Jun 24, 2020 at 11:12 AM pylang <pylang3@gmail.com> wrote:
Great timing! Last week I was trying to emulate a certain Rust example in Python.
Rust has a way to implement families of classes without subclassing,
which I think could be a great addition to Python someday.  I'll explain below.

Here is a Rust example (https://youtu.be/WDkv2cKOxx0?t=3795)
that demonstrates a way to implement classes without subclassing.
# Rust Code
enum Shape {
    Rectangle(f32, f32)

impl Shape {
    fn area(self) -> f32 {
        match self {
            Shape::Circle(r) => 3.1 * r * r,
            Shape::Square(l) => l * l,
            Shape::Rectangle(l, w) => l * w

fn main () {
    let c = Shape::Circle(3.0);
    let s = Shape::Square(3.0);
    let r = Shape::Rectangle(3.0, 7.5);
    println!("○ {}", c.area());
    println!("□ {}", s.area());
    println!("▭ {}", r.area());

# Output
○ 27.899998
□ 9
▭ 22.5

The general idea is:
- declare classes that share a certain type
- extend common methods with a match-case style

That's it.  No sub-classing required.  

I wondered if someday, can we do this in Python? This match-case proposal seems to fit well in this example.

While I know this PEP does not focus on detailed applications,
does anyone believe we can achieve elegant class creation (sans subclassing) with match-cases?  

On Wed, Jun 24, 2020 at 2:04 PM Guido van Rossum <guido@python.org> wrote:
On Tue, Jun 23, 2020 at 11:27 PM Emily Bowman <silverbacknet@gmail.com> wrote:
> I wonder if it's time to officially designate _ as a reserved name.

Alas, it's too late for that. The i18n community uses _("message text") to mark translatable text. You may want to look into the gettext stdlib module.

--Guido van Rossum (python.org/~guido)
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Pronouns: he/him (why is my pronoun here?)