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What’s New in Python 3.8

docs.python.org

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Re: What’s New in Python 3.8

#111

Post by jtdev »

Pxtl wrote: post #66

Ugh, I hate assignment expressions. I liked that they were missing from Python. I've been coding in algolesque languages for 20 years and hiding assignments inside of expressions instead of putting them on the left like a statement has always tripped me up.

But, but, but... now you don’t need to write that extra line of code! It’s going to make everything sooooo much better, code will practically write itself now.

I’ll just leave this here:

“There should be one—and preferably only one—obvious way to do it.”

Re: What’s New in Python 3.8

#112

Post by est »

geofft wrote: post #69
CivBase wrote: post #22

As a developer who has primarily developed applications in Python for his entire professional career, I can't say I'm especially excited about any of the "headlining" features of 3.8. The "walrus operator" will occasionally be useful, but I doubt I will find many effective uses for it. Same with the forced positional/keyword arguments and the "self-documenting" f-string expressions. Even when they have a use, it's us…

> The "walrus operator" will occasionally be useful, but I doubt I will find many effective uses for it. The primary one I want is if m := re.match(...): print(m.group(1)) and while s := network_service.read(): process(s) both of which are both clearer and less error-prone than their non-walrus variants. The other one that I would have found useful an hour ago is in interactive exploration with comprehensions. I freq…

IMHO the whole `re.match` is a design flaw in stdlib.

re.match() should always return a match object, but instead .group(1) will return None. Then we can write one-liners easier without the walrus operator.

Re: What’s New in Python 3.8

#113

Post by ben509 »

j88439h84 wrote: post #17
ohazi wrote: post #14

> The typing module incorporates several new features: > A dictionary type with per-key types. Ah, I've been waiting for this. I've been able to use Python's optional types pretty much everywhere except for dictionaries that are used as pseudo-objects, which is a fairly common pattern in Python. This should patch that hole nicely.

IMO A better fix is to use http://attrs.org or dataclasses to replace the dicts entirely.

And then use a library like json-syntax[1] to translate those into JSON.

[1]: https://pypi.org/project/json-syntax/

Re: What’s New in Python 3.8

#114

Post by hermitdev »

3PS wrote: post #92
drdaeman wrote: post #86

Earlier quoted context omitted.

Coming from Perl, I used to want this badly, but then I thought that there's absolutely nothing wrong with m = re.match(...) if m is not None: pass Now, I wonder what you meant saying that single-line version is less error-prone, because I don't think so. I believe they're exactly the same in this regard, except for a bizarre case when someone would bastardize the code by putting some irrelevant lines between the ass…

The issue, in my opinion, is when you want something like this: while m := f(many, args): # do stuff with m Now, if you're writing this in Python 3.7, you often end up with some code duplication: m = f(many, args) while m: # do stuff with m m = f(many, args) # duplicate Or something like this: while True: m = f(many, args) if not m: break # do stuff with m Personally, I consider the last version to be the most elegan…

I literally wrote your last example twice last week to hash files in 4k chunks. Those 4 lines would be reduced to 1 with the walrus operator. I welcome it, as well.

Edit: 1 line, not 2 (excluding the "do stuff")

Re: What’s New in Python 3.8

#115

Post by nine_k »

est wrote: post #112
geofft wrote: post #69

Earlier quoted context omitted.

> The "walrus operator" will occasionally be useful, but I doubt I will find many effective uses for it. The primary one I want is if m := re.match(...): print(m.group(1)) and while s := network_service.read(): process(s) both of which are both clearer and less error-prone than their non-walrus variants. The other one that I would have found useful an hour ago is in interactive exploration with comprehensions. I freq…

IMHO the whole `re.match` is a design flaw in stdlib. re.match() should always return a match object, but instead .group(1) will return None. Then we can write one-liners easier without the walrus operator.

Sometimes you just check for a match (e.g.of entire string) and define no groups.

The problem is not in re.match but in None being a relatively poor Maybe / Optional (still ways better than C-style `null` of many other languages).

Re: What’s New in Python 3.8

#116

Post by est »

nine_k wrote: post #115
est wrote: post #112

Earlier quoted context omitted.

IMHO the whole `re.match` is a design flaw in stdlib. re.match() should always return a match object, but instead .group(1) will return None. Then we can write one-liners easier without the walrus operator.

Sometimes you just check for a match (e.g.of entire string) and define no groups. The problem is not in re.match but in None being a relatively poor Maybe / Optional (still ways better than C-style `null` of many other languages).

> Sometimes you just check for a match

re.match vs re.search

Re: What’s New in Python 3.8

#117

Post by kps »

grincho wrote: post #85
robocat wrote: post #56

Earlier quoted context omitted.

There are programming fonts that use ligatures to convert >= to ≥, or -> to →, so the source code remains in ASCII but symbol sequences show as unique Unicode characters. A next step could be for common dev environments to actually convert symbol/key sequences to operators (how do APL programmers do it?) Avoiding ambiguity and semantic overloading of ASCII symbols would surely help beginners (if also given a UI that…

The Mac has provided easy access to symbols since 1984, with nice mnemonics like these: option-= ≠ option- ≥ option-/ ÷ option-o ø option-w ∑ I don't know why other OSes haven't adopted something similar. The first couple of these were even idiomatic in HyperCard's scripting language.

X has Compose, which originated slightly earlier (the key, that is, not the X11/xkb implementation), and is a tolerable alternative. e.g. [Compose / =] ↦ [≠]

Re: What’s New in Python 3.8

#118

Post by kps »

robocat wrote: post #98
grincho wrote: post #85

Earlier quoted context omitted.

The Mac has provided easy access to symbols since 1984, with nice mnemonics like these: option-= ≠ option- ≥ option-/ ÷ option-o ø option-w ∑ I don't know why other OSes haven't adopted something similar. The first couple of these were even idiomatic in HyperCard's scripting language.

That's like visual puns, and is limited to whatever symbols seemed important to the developer at the time. How do you discover how to type ß, °, «, ‡ etc? Android's gboard uses phonetics (long press [s] key for ß), symbolic similarity (long press [*] key for ‡) and visual similarity (long press [<] key for «) which is guessable for some symbols, but isn't discoverable for others (you can search for emoji by name, but…

It's easy on the Mac to have a custom or purpose-built keyboard layout that makes sense for the user or context. It's a little harder with X (mostly due to uncoöperative DEs) but still doable.

Re: What’s New in Python 3.8

#119

Post by hermitdev »

CameronNemo wrote: post #67
cfors wrote: post #34

Earlier quoted context omitted.

It’s a business play. If companies don’t want to move off 2.x and are willing to pay a Software vendor to backport security fixes so that they can CYA, so be it.

Easy. Don't buy products that are obviously still using python2. Problem should solve itself in some time. Hard to tell sometimes, but looking at dependencies and plugin languages is a good way.

The only software I've written in Python that's been sold was written against 2.5 and has long been out of my control. We sold the source to the sole client (was a financial services migration tool for a very specific domain during a joint venture; I can't divulge anymore).

I know longer work at the company, but i'd wager that the client wouldnt have been willing to pay $500/hr (the rate my company billed me out at for support, features, etc), 10 years ago, to have me port the app and the handful of 3rd party dependencies to Python 3.

Moving from 2 to 3 took a while. I moved once the libs I used moved. For an "app" developer, the migration was easy once my dependencies were ready. Most of the changes were straightforward. The print statement becoming a function was easy. str becoming Unicode and introducing bytes has been a headache. Still having issues time to time with text encoding, especially with encoded text dealing with SQL Server (looking at the default CP-1252 for US English). Another one that still trips me up is is needing a "newline=''" argument when opening as CSV file.

That said, I love Python 3. Ita mostly about forgetting/relearning old syntax, which is going to happen for anything youve been using for decades and undergoes a significant change. I started with Python over 15 years ago, at version 2.2, for reference.

Re: What’s New in Python 3.8

#120

Post by hermitdev »

j88439h84 wrote: post #17
ohazi wrote: post #14

> The typing module incorporates several new features: > A dictionary type with per-key types. Ah, I've been waiting for this. I've been able to use Python's optional types pretty much everywhere except for dictionaries that are used as pseudo-objects, which is a fairly common pattern in Python. This should patch that hole nicely.

IMO A better fix is to use http://attrs.org or dataclasses to replace the dicts entirely.

One of the features I'm looking forward to using is the kwdargs support in dataclasses. Honestly, find it so much more useful and intuitive than the 3.7 positional only.
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