What’s New in Python 3.8

Post by xamuel » Tue, Oct 15, 2019, 3:00 PM UTC

CreRecombinase wrote: post #310

xamuel wrote: post #307

Earlier quoted context omitted.

I don't understand why anyone would want singledispatch. Instead of having the function defined in one place where you can look it up, now the function is potentially scattered all over the place. (I'm not talking hypothetically. I've had the 'pleasure' of working on a codebase where different singledispatch cases of the same function were defined in different files!)

Because if you need to branch based on type more than a few times in your function it can get pretty hard to read. Am I right that the basis of your complaint is that it's now harder to find all the members of (what you'd call in C++) the "overload set" for a particular function? If so I can see your point.

Post by DonaldPShimoda » Tue, Oct 15, 2019, 3:08 PM UTC

fjp wrote: post #316

DonaldPShimoda wrote: post #312

Earlier quoted context omitted.

> I'm still looking forward to using assignment expressions for testing my re.match() objects. The fact that this is the go-to example that everybody is using in justifying the introduction of the assignment expression convinces me that the real problem lies with the re module's API. (To be clear: I will also be using assignment expressions for this case, but I don't think assignment expressions are really in line wi…

re's API sucks but I'm looking forward to safe dictionary access with assignment as well. No more if my_map.get(key) is not None: // do something with my_map[key]

    match my_map.get(key):
      case None:
        // do thing (or nothing, i.e., pass)
      case Some(val):
        // do other thing

Post by ciupicri » Tue, Oct 15, 2019, 3:20 PM UTC

zb wrote: post #313

ciupicri wrote: post #311

Earlier quoted context omitted.

Instead of raising StopIteration you could also just return from the function. You could also make it a bit shorter if you swap the if branches. def f_iter(many, args): while True: m = f(many, args) if not m: return yield m

Instead of raising StopIteration you have to return from the function, otherwise you'll just get a RuntimeError starting with Python 3.7.

Post by omginternets » Tue, Oct 15, 2019, 3:24 PM UTC

Liquid_Fire wrote: post #308

probably_wrong wrote: post #270

Earlier quoted context omitted.

I feel the same way as you do. For me, which version of an interpreter I'm using should be the kind of issue I only need to worry when solving extremely specific, deep-level problems. Python 3+ breaks this pact too often for my taste. Considering this f-string example taken from another announcement: f"Diameter {(diam := 2 * r)} gives circumference {math.pi * diam:.2f}" This is valid Python 3.8, but it's not valid in…

I'm not sure why you frame this as an issue with Python 3. This has always been the case, even in the 2.x days every release added new features, and if you ran code using them in an older version it wouldn't work. The minor releases are always backward-compatible, so just run the latest version and everything will work.

Post by diminoten » Tue, Oct 15, 2019, 3:33 PM UTC

jimktrains2 wrote: post #57

diminoten wrote: post #25

Earlier quoted context omitted.

Not misunderstood; luddites (lowercase l, or at least the generalized form) means something different than Luddites (capitalized L).

I'm fairly certain the lowercase l version is the same, but the Luddites are remembered as being ant technology, not pro labour.