What's Coming in Python 3.8

Post by wil421 » Wed, Jul 17, 2019, 9:55 PM UTC

Post by nerdponx » Wed, Jul 17, 2019, 9:56 PM UTC

ashton314 wrote: post #53

stakhanov wrote: post #10

Speaking as someone who has written Python code almost every day for the last 16 years of my life: I'm not happy about this. Some of this stuff seems to me like it's opening the doors for some antipatterns that I'm consistently frustrated about when working with Perl code (that I didn't write myself). I had always been quite happy about the fact that Python didn't have language features to blur the lines between what…

Many languages don't distinguish between statements and expressions—in some languages, this is because everything is an expression! I'm most familiar with these kinds of languages. I'm not familiar much with Python, beyond a little I wrote in my linear algebra class. How much does the statement/literal distinction matter to readability? What does that do for the language?

Post by RaptorJ » Wed, Jul 17, 2019, 9:57 PM UTC

txcwpalpha wrote: post #97

nneonneo wrote: post #74

Earlier quoted context omitted.

Regular = can only be used in statements. Walrus := can only be used in expressions. There's no overlap there. However, := does simplify certain expressions (like those nested if-else statements and the common "while chunk := read()" loop), which I think does justify its existence.

This honestly makes it seem more confusing to me. The fact that there is now an operator that can only be used in certain statements just makes things more confusing. And if there really is no overlap, then why wasn't the "=" operator just extended to also work in expressions? "while chunk = read()" seems like it makes just as much sense without adding the confusion of another operator.

Post by thaumasiotes » Wed, Jul 17, 2019, 9:57 PM UTC

txcwpalpha wrote: post #105

thaumasiotes wrote: post #73

Earlier quoted context omitted.

Read it "if y" - that's what's being tested. The walrus simultaneously names the value being tested so you can refer to it within the condition; it's sort of the inverse of Perl code using $_. So instead of if (do_something()) { act_on($_); } you have if placeholder := do_something(): act_on(placeholder) But when reading aloud, however you'd read the perl will flow as more natural english. "If the string contains z,…

>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…

    if x := y():
        act_on(x)

    if y():
        act_on(y())

Post by Areading314 » Wed, Jul 17, 2019, 9:58 PM UTC

londons_explore wrote: post #70

I long for a language which has a basic featureset, and then "freezes", and no longer adds any more language features. You may continue working on the standard library, optimizing, etc. Just no new language features. In my opinion, someone should be able to learn all of a language in a few days, including every corner case and oddity, and then understand any code. If new language features get added over time, eventua…