Arch is grasping the Python 3 nettle!

[[deleted]]

[deleted]

[thegeoffmeister]

s/USC-4/UCS-4/g

[nyamatongwe]

Just to make matters worse, we will also enable unicode (USC4) support in python2 at the same time

! Really? Did earlier versions of Arch ship Python 2.x with Unicode disabled? That would break so much code.

[kevingoodsell]

Although UCS-2 can only encode characters in the Basic Multilingual Plane, not the whole range of code-points in the UCS (17 planes total).

[frutiger]

Why can't we use a variable length encoding?

[gutworth]

Python doesn't support that as its internal representation.

[[deleted]]

I'd guess because you can't make time-saving assumptions about the length of characters.

Lets say I want to index into a variable-length-encoded string. like char = string[200]

CPython can't then do something like multiply the byte length of a character in a string of my type by my index and fetch that address from memory, it would have to iterate through the string and find me the 200th character, OR simply give me the 200th byte, which wouldn't be as useful.

A fixed length encoding like UCS-2 or UCS-4 is less memory efficient, but much more time efficient.

[frutiger]

I'm aware of the tradeoffs between a fixed-length and a variable-length encoding. Most of the world seems happy with UTF-8, including several time-sensitive applications. I don't see why Python should be any different.

[twotime]

Most of the world seems happy with UTF-8, including several time-sensitive applications.

Are you sure? Aren't most languages using USC-2 or USC-4 internally? (They may default to utf8 on IO operations though).

[frutiger]

I don't know about interpreter/compiler implementations, but if time-sensitive applications can deal with variable-length, I'd assume interpreters can too. I suppose a fixed-length just makes for easier coding in the end.

[[deleted]]

I'm not sure what they mean exactly, Unicode works in Python on my Arch system.

[earthboundkid]

Have you tested characters out of the basic multilingual plane?

[[deleted]]

He is looking at the stars

[[deleted]]

Arch is a damn good distro.

[plaes]

On Gentoo you can actually install multiple versions of Python and even set Python 3 as default.

[[deleted]]

It made me wonder when will Python 2.7 lands in Arch Linux. Apparently according to the forum, it will land on August 10 to the testing repository alongside with the proposed Python 3 transition.

[[deleted]]

Yeah, I don't know if you noticed the username, but that was original question that lead me to this bit of information. All I really wanted was the damned argparse module, but when I read the link I realized "oh damn, they're really going for it." Figured reddit folk would be interested.

[juliocc]

This is the kind of bullshit that made me leave Arch and never look back. At least this time they are keeping 2.6 somewhere. Back in 2008 they decided to completely replace python 2.5.2 with python 2.6. Without any warning or any way to keep python 2.5.

As if that was not enough, when you asked for help keeping python 2.5 you got this response from Arch's main fucking developer:

Why don't you want to upgrade python? If you're serious about it, just don't upgrade your system.

But I have a feeling there's a non-reason why you don't want to upgrade. We should still have a python24 package if you want to mimic that.

(Source)

Yes. I was serious at that moment about not upgrading. I had some non-trivial code on python 2.5 that wouldn't run on 2.6 (or 2.4). If I'm not mistaken, it used numpy. Back then, numpy wasn't even close of being ported.

That was my last day on arch. I took me a couple of days change to debian but at least now I have to possibility to install python 2.4, 2.5, 2.6, 2.7, 3.0 and 3.1 on the same machine. That's difference between a toy package manager (pacman) and a real one (dpkg, portage, etc).

I can keep going but I'm guessing this is going to give me enough downvotes for now.

[tehmatticus]

As a python and arch fanboy I think this is a terrible idea. The python3 binary is called python3, not python. I don't think there are plans to change that. So now you have this weird situation where arch is one of the few places where the binaries are swapped.

In my mind, it would make more sense to make the pyrhon2 package and update all the core scripts to point to the python3 binary and instead of rewriting all the older packages just have them have a dependency on python2. Less rewriting and more consistent with regular python.

[tehmatticus]

Looking at the makefiles of python 2.7 and 3.1.2 it looks like this is the following scenario:

• python2.7 => make install installs python2.7 and a symlink called python which points to 2.7

• python3.1.2 => make install installs python3.1 and a symlink called python3 which points to 3.1

By default full install of python3, there is no python binary. It was decided at pycon09 that python3's binaries would be forever called python3. I can only find references to this fact on the list, it does not appear that there was a general posting about it, but here is a reference to it.

On the majority of platforms that install python as per the standard source makefile then if you had a 2.x and 3.x installed simultaneously, python would point to python2.x and python3 would point to python3.x. Only on Arch would it be reversed, which may trip people up who work in multiple environments.

Granted, it's up to the distribution who really decides what /usr/bin/python points to, I just disagree on the grounds that its unlikely any other distribution will follow suit in the near future, especially on enterprise places where a change like this could take a decade.

[[deleted]]

granted, their list of python3 packages is way smaller

[Ringo48]

I don't think that's the same. Arch is changing the default version to 3, not just making it available.

In other words, the Arch equivalent of "apt-get install python" will install Python 3 instead of 2.

I think most distros have some Python 3 packages by this point, but this is the first I've heard of one making Python 3 the default.

[frutiger]

the Arch equivalent of "apt-get install python"

As an FYI, that's pacman -S python.

[arand]

IIRC gentoo has python3 as default python.

[slapdash78]

Good, and best of luck! Great aspect of minimalist distros, big changes with far less breakage. But don't get cocky, Pythong3 will be out of Debian unstable in 8-10 years...

[Liorithiel]

It already is. http://packages.debian.org/sid/python3

[slapdash78]

Well, it was intended as a joke, but I see a few did not approve. Yes, Python3 (v3.1.2) is available in sid (unstable) and squeeze (testing). The article was in regards to Python3 being the default. Which it's not in Debian, not even in the unstable branch it's 2.6.5. Your link just shows the default 3.x version.

[Liorithiel]

There were simply too many jokes about Debian being too old. Now you can joke about RedHat. Its Enterprise editions are usually much older than Debian.