(Jakub, next time please trim the original post from your quote to what's
necessary.)
On Wed, Jun 24, 2020 at 9:11 AM <ja...@stasiak.at> wrote:
> Wow, I totally didn't see this coming, not after seeing what seems like a
> lot of rejected ideas on this topic (there was at least one PEP already
> that proposed this, right?). I have to admire the authors' determination to
> write such a lengthy and (from skimming it) complex and comprehensive
> proposal *and* providing a reference implementation on top of that, the
> amount of work (including internal bikeshedding) must've been substantial.
>
> Needless to say it's +1 from my humble person, big time, and I wouldn't
> want the comment below to detract from that.
>
> So, now for the one thing that makes me unhappy: the rejected idea to make
> it an expression. In my short experience with pattern matching, mainly in
> Rust, roughly half (very vague estimate) of its usefulness came from it
> being an expression. It's even small things like
>
> let i = match i {
> 9 => 10,
> 10 => 9,
> _ => i,
> };
>
> and
>
> let mut file: Box<Write> = match filename.as_ref() {
> "-" => Box::new(io::stdout()),
> _ => Box::new(File::create(filename).expect("Cannot open file for
> writing")),
> };
>
> and it adds up. I'm not sure how to approach this with Python syntax and
> I'll think about this, but I feel that it'd be a huge missed opportunity to
> not have this.
>
We considered it, but it simply doesn't work, for the same reason that we
haven't been able to find a suitable multi-line lambda expression. Since
Python fundamentally is not an expression language, this is no great loss
-- you simply write a match statement that assigns a value to the variable
in each branch. Alternatively, the match could be inside a function and
each block could return a value.
--
--Guido van Rossum (python.org/~guido)
*Pronouns: he/him **(why is my pronoun here?)*
<http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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