What's Coming in Python 3.8

Post by shakna » Thu, Jul 18, 2019, 1:59 AM UTC

thaumasiotes wrote: post #117

txcwpalpha wrote: post #105

Earlier quoted context omitted.

>Read it "if y" - that's what's being tested. Once way to test if this works is to take the code, read it aloud, and then use the read-aloud version to rewrite the code. If you don't have a high degree of certainty that you end up with the same code, something has failed along the way. In this case, if I take "if x:= y()" and read it aloud as "if y", I think the vast majority of people would translate that to code as…

You will end up with the same code under two conditions: 1. You read more than one line of code. 2. Executing the code in the conditional more than once doesn't matter. If you meet those two assumptions, then the reading I suggested will transform this if x := y(): act_on(x) into this if y(): act_on(y()) which is, in fact, the same thing.

Post by ben509 » Thu, Jul 18, 2019, 2:04 AM UTC

zephyrfalcon wrote: post #313

ben509 wrote: post #292

Earlier quoted context omitted.

You don't even need the locals() function to get into trouble: x = [1, 2, 3, 4] def foo(): x[0] += 3 # Okay def bar(): x += [3] # UnboundLocalError def qux(): x = [5, 6, 7, 8] # Binds a new `x`.

def bar(): x += [3] # UnboundLocalError This is an especially funky one. x.extend([3]) would be allowed. Presumably x += [3] is not because it expands to x = x + [3]... However, the += operator on lists works the same as extend(), i.e. it changes the list in-place.

              0 LOAD_FAST                0 (x)
              2 LOAD_CONST               1 (3)
              4 INPLACE_ADD
              6 STORE_FAST               0 (x)
              8 LOAD_CONST               0 (None)
             10 RETURN_VALUE

Post by kragen » Thu, Jul 18, 2019, 2:16 AM UTC

RhodesianHunter wrote: post #293

tachyonbeam wrote: post #180

Earlier quoted context omitted.

I'm 34 and I don't like this, so it's definitely not only those above 35. Jokes aside, I would say I'm a minimalist and this is where my resistance comes from. One of the things that I dislike the most in programming is feature creep. I prefer smaller languages. I like the idea of having a more minimal feature set that doesn't change very much. In a language with less features, you might have to write slightly more c…

> In a language with less features, you might have to write slightly more code, but the code you write will be more readable to everyone else. I disagree with this, which is precisely why I prefer feature rich languages like Java or better yet Kotlin. It doesn't get much more readable than something like: users.asSequence() .filter { it.lastName.startsWith("S") } .sortedBy { it.lastName } .take(3) Now try writing tha…

    sorted((u for u in users
           if u.last_name.startswith("S")),
           key=lambda u: u.last_name
    )[:3]

    sorted((u for u in users
           if last_name(u).startswith("S")),
           key=last_name
    )[:3]

Post by donio » Thu, Jul 18, 2019, 2:18 AM UTC

marmada wrote: post #241

simondw wrote: post #62

Earlier quoted context omitted.

But now there are two ways to do assignment. That's not very pythonic, is it?

I never felt like there was only one way to do something in Python. Every Stack Overflow question has a multitude of answers ranging from imperative to functional style and with various benefits and drawbacks. Python is one of the least "only one way to do things" languages I've used. This even extends to its packaging system, where you can choose between virtualenv, pipenv, pyenv, etc. Same goes for the installation…

Post by ben509 » Thu, Jul 18, 2019, 2:24 AM UTC

toxik wrote: post #278

nerdponx wrote: post #207

Earlier quoted context omitted.

I envisioned it like "if/else" or "for/else" or "while/else", where a "do" block must be followed by a "while" block. x = 0 do: x += 1 while: x

This completely contradicts the rest of Python grammar, and indeed many languages’ grammars. The consistent way would then be `while x < 10` but that too looks ridiculous. The issue is that you can’t have post-clause syntax in Python due to its infamous spacing-is-syntax idea.

    do:
        body()
        body()
    while x