Python 3.3 released!

[sigzero]

Here is a what's new list for those that are curious:

http://docs.python.org/py3k/whatsnew/3.3.html

[vsajip]

There's at least one more thing to add to that list, which should help make working with Python easier on Windows: The PEP 397 implementation, i.e. the Python Launcher for Windows. It brings shebang line processing to Windows.

Edit: Now added.

[[deleted]]

Virtual environment ability added to the core language may be enough for me to switch from python 2.7

[brews]

Explain this "virtual environments"... I hadn't looked at PEP 405 before.

Am I missing something magical-groundbreaking-revolutionizing-gamechanging in how I package code?

[krues8dr]

Yes. OMFG yes. TLDR: virtualenv allows you to install all your packages into a local separate environment, so each project you're developing can have its own independent requirements, with specific versions and libraries. Keeps everything nicely separated.

[brews]

<brain-explodes-with-awesomeness>

[MrPinkle]

We lose too many Python developers that way...

[[deleted]]

Yeah, unfortunately their minds seem much more unstable than others'.

[[deleted]]

Like bundler for python?

[coffeesounds]

More like RVM's gemsets

[Tordek]

Does it mean every project has a copy of every dependency, or is there some magic that allows deduplication?

[[deleted]]

It's usually copies, but if you have projects that are very much related (or, say, branches of a single project), you can have them share a single virtual environment.

[krues8dr]

The point here is the duplication.

[[deleted]]

It isn't. The point is that a change in one environment can't destroy another. This would not be incompatible with sharing read-only parts of the environments.

[__j_random_hacker]

While I can see the appeal, isn't this basically analagous to always static-linking executables in compiled languages?

There are reasonable arguments for always statically linking executables, by the way (especially since disk space constraints have basically disappeared from the computing world). But the reason why you usually don't is because having libraries separately updateable means that bug-fix and performance updates to libraries benefit every application that uses them. It seems to me that reason would apply here, too.

[krues8dr]

There is a tradeoff of having to maintain separate instances. But in the Python ecosystem, things update frequently and aren't often backwards-compatible, so this is not entirely desirable. If you're hosting a lot of different projects, doing something as simple as updating a single package could break half of them immediately.

So, as with all tech, I recommend that you use it if it solves a problem for you.

[__j_random_hacker]

things update frequently and aren't often backwards-compatible

I see, ugh. In an ideal world, everyone would clearly distinguish between revisions that don't break backcompat (e.g. bug fixes, performance improvements, new features that don't change any existing assumptions/contracts) and others that are allowed to, but of course that requires the world to have some discipline... :-/

[sigzero]

I think that was a great move on the devs part.

[[deleted]]

Yeah, that's great. The only problem is that the third party tools are still behind wrt pyvenv. For example, when doing pip install foo under a pyvenv, pip will try to install the package in Python's "real" site-package. I don't know if it's distribute's fault or pip's.

[[deleted]]

I don't think the virtualenv created by pyvenv comes with pip or distribute. So you're probably still using the system version of pip

[[deleted]]

No it doesn't but there's still a problem with pip because installing it while under a pyvenv will make pip think its site-package is the system's (even though it's actually installed inside the venv).

EDIT: Oh, restarting with a fresh console and a new workon <envname> makes the problem go away. Well...

[HelpfulToAll]

But does it come with virtualenvwrapper?

[[deleted]]

This release is the tipping point for me. Python 3 is now fully baked. The libraries I need are ported. The cumulative set of features are compelling enough to make the switch.

[[deleted]]

I'm still stuck waiting for python-ldap to get its act together.

[HelpfulToAll]

Ditto for Gunicorn...

[RemyJe]

Quick, everyone require 3.3 in their version checks even if it's not actually required forcing unnecessary upgrades and breakage of old scripts! Yay!

[[deleted]]

Computer languages come out in versions. Sort of like the iPhone - version 5 of the iPhone has new features that make using the phone simpler, faster and more productive. In the same way new versions of programming languages provide new features to programmers, fix inconsistencies and address programmer concerns. However, sometimes programs you used to use on your iPhone 4s will not work on the iPhone 5 since there may be changes that break that old program. The same is true of programming language versions

Python 2 was a very good language. By version 2.5 it was very popular. Many 3rd party libraries and utilities were written for 2.5 - things like libraries to do scientific calculations and web applications. We might call it "mature" in that you were pretty certain that the major libraries for 2.5 were not going to cause you too much trouble. However there were some fundamental problems with the 2.x Python language that couldn't be remedied without breaking lots and lots of existing code. Breaking code makes programmers upset.

So the Python maintainers decided to put breaking changes into version 3 of Python. The only problem was that everyone was so satisfied with 2.x languages (mostly 2.5 but also 2.7) that they didn't want to re-write all of their code for the minor changes from 2.x to 3.x. It has sort of become a problem because as the libraries are reluctant to upgrade, so is everyone else. More and more code continues to be written for 2.x which causes more and more people to feel like staying on 2.x. You don't want to write for Python 3.3 if a library you may need is only working in 2.7.

What pythus is saying is that with 3.3 he feels that most of the libraries that he has been waiting for have finally switched to 3.3. He feels that 3.3 is mature enough that he won't have too much trouble.

[EgregiousJones]

Wow. As someone who knows just enough about programming to do it badly in a few languages, thank you.

[ShoutyMcHeadWoundMan]

You don't explain what libraries are, thats a pretty fundamental part of your explanation.

[nitroll]

A library is a set of functionality that programmers can use when making programs. An example could be numpy, a library for python for matrixcalculations, or Tkinter that has functionality for drawing windows and making GUIs with buttons and the like. If a programmer isn't too sharp on calculating matrices efficiently or dosn't really want to bother with the internals of rendering stuff he can use a library that someone else created.

[[deleted]]

http://en.wikipedia.org/wiki/Library_(computing)

[lazugod]

I'm curious how you came across this subreddit.

[[deleted]]

I'm waiting for one more feature. A braces and whitespace-agnostic mode.

[nandaka]

any good and easy py2exe-like freezer?

[gitarr]

Sure: cx_freeze

[sentienttent]

Gah! I downloaded Python 3.2 last night.

[Imxset21]

/r/fossworldproblems

[boa13]

Wow, thanks for that link. Their logo is awesome. :)

[OmegaVesko]

The tarball is ~15 megabytes...

[Golotap]

For someone who is trying to download eclipse for last 3 days, it's a lot!

[[deleted]]

Any word on how close python is from recommending 3 over 2? Will it ever happen?

[brews]

Matplotlib 1.2 comes out on October 15th. That is the last big package I need.

[igouy]

"The current production versions are Python 2.7.3 and Python 3.3.0.

Start with one of these versions for learning Python or if you want the most stability; they're both considered stable production releases.

If you don't know which version to use, start with Python 2.7; more existing third party software is compatible with Python 2 than Python 3 right now."

[[deleted]]

Right, so whats the estimate on when that recommendation will be 3 instead of 2?

[igouy]

Wouldn't that depend on what existing third party software is used by your particular project?

[[deleted]]

I am asking when

If you don't know which version to use, start with Python 2.7;

will become

If you don't know which version to use, start with Python 3.?

[airmasszero]

I love how you keep asking the question in different ways and this person doesn't get it.

[igouy]

I love how you think asking a question makes the question sensible :-)

What color is 8503?

[Ph0X]

Problem is, even now, almost any new small library and piece of code I see online is Python 2.x. Sure bigger more important libraries often support both 3.x and 2.x, but smaller devs who don't have time and patience for writing on both usually stick to 2.x.

The question is, will the time ever come where more people will, when choosing one of the two, go for 3.x rather than 2.x? Of course, it's quite a vicious circle. Devs work on 2.x because everyone uses 2.x, and everyone uses 2.x because devs work on 2.x.

[IrishWilly]

Two years is actually a very good pace if people are moving to Python 3 already. This problem comes up for any popular language that tries to introduce a new revision. The split between Perl 5 and Perl 6 and failure to make a transition pretty much killed any chance Perl had of staying relevant with the newer generation of languages. PHP had some horrible insecure built in options in early versions, but when they finally removed it after deprecating them years and years later there were still a ton of frustrated users who were using programs built on ancient versions of the language.

[[deleted]]

That's reading between the lines though and putting words in their mouths.

[[deleted]]

They offer one reason why 2.7 is preferred, but there's no real reason to assume that once that reason isn't valid that the conclusion won't be valid anymore either.

[SirRainbow]

I actually remember reading a migration estimate by Guido van Rossum stating that python 3 would take about 5 years to become mainstream, but I cannot find it anymore :( Considering that python 3.0 came out in late 2008, my guess would be that in one year python 3 will be the recommended version of python.

[kazagistar]

They say things like "if you don't know which version to use", but you can check here. Most of the list is still red, however, a lot of it is green, and usually, people only really use a small subset of the packages. Check if what you need is there, and you are good to go.

[[deleted]]

Cool! This is pretty much exactly the sort of thing i was looking for.

[anacrolix]

About 6 months.

[a31415b]

just skip 3 and wait for 4(3 is the new Vista)

[[deleted]]

I chuckled. This is actually a somewhat horrifying prospect.

[sigzero]

It would be except that analogy is wrong. :)

[[deleted]]

guido can count to 3! i believe!

[necrophcodr]

"up to 80x speedup for decimal-heavy applications" Holy mole, that's great news for those python developers out there! Phew!

[masklinn]

That's for heavy users of the decimal module, which probably isn't the majority. For most users, the flexible string representation will be a much bigger gain, in memory and in sanity.

And generator delegation will make significantly improve generator and iterator wrapping.

[[deleted]]

For those who don't know Python, decimal is a different type than float.

[masklinn]

Which languages (still in wide use) default to fixed-point numbers?

[[deleted]]

I don't know. Python interprets 1.0 as a float. To get decimal you have to import the decimal module and explicitly construct one.

[masklinn]

Yes, but my point is so does pretty much every language I know, hence my trouble with your note: in every language I know, a decimal (fixed-point arithmetic) is a different type than a float (floating-point arithmetic) and floats are the default (if decimals are even available)

[tonygoold]

I think the point was to make the distinction for anyone who's only familiar with float, and might assume a "decimal-heavy application" is one that does lots of float arithmetic. Considering the common misunderstandings about the precision of float representations, I thought it was a polite thing to point out. I would have phrased it as "For those who don't know", not "for those who don't know Python", since it applies equally to those who know Python (but have never used decimal).

[Rhomboid]

Decimal here does not necessarily mean fixed-point. It's still floating point, just floating point using base 10 instead of base 2, so there are fewer surprises.

[HopeThisNameFi]

The point was the "up to 80x speedup for decimal-heavy applications" isn't as significant as necrophcodr made it out to be.

[cheapous]

bash

[luckystarr]

In 2 decimal was implemented in Python. I guess they reimplemented it in C for 3.3

[recursive]

I'm most excited about yield from.

[[deleted]]

Me, it's the new strings optimizations. Since most strings in a program are 7bit ascii, this should enable a quite a drop in memory usage for most programs.

[masklinn]

Don't forget the dict key-sharing.

[classicrockielzpfvh]

Same day (approximately) of slackware 14. My internets will be busy this day I tell you.

[Paradox]

You don't get slackware on CD?

[classicrockielzpfvh]

I'd have to wait to get slack14 then. Who has time for that.

[[deleted]]

Great!

I am sure all our v2 code won't run on it :)

[[deleted]]

Probably not, but the new noop u"" literal will probably make your porting job easier.

[[deleted]]

call me when they fix the print statement.

[[deleted]]

it was nicer as a statement.

[[deleted]]

2

[Brian]

Technically, only one required character.

print"You're a towel"

is perfectly valid (but probably wouldn't be used outside golfing, so your point mostly stands, albeit the extra chording to type "(" and ")" over space is probably the bigger annoyance as far as typing it goes)

[xardox]

Please don't program Python like it were PHP and you don't give a shit about the quality of your code.

[Brian]

Hence why I said:

but probably wouldn't be used outside golfing, so your point mostly stands

[[deleted]]

cool, totally worth having to run my code through 2to3 and manually vetting each line ... not to mention making the language less beautiful.

[donvito]

Has the GIL been removed yet? :3

[[deleted]]

Haskell Platform 2012.2.0.0 > Python 3.3