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Making Python 3 more attractive

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Re: Making Python 3 more attractive

#131

Post by actsasbuffoon »

plesner wrote: post #41

Making python 3 more attractive is not the solution, it's part of the problem. I can't use just python 3 because python 2 is still widely used. I can write code that works on both but now I'm using the worst of both worlds, and even worse I now have to test on both. And that'll last until python 2 goes away completely which, - when has a language ever gone away quickly? These aren't fun problems. Improving python 3,…

Making print a statement again could break a lot of Python 3 code. In Python 2 it's a statement, and statements can't appear in lambdas. In Python 3 it's a function call, and function calls are expressions, which can appear in lambdas.

I don't think it could (easily) be resolved by treating it like a function when followed by parens and a statement otherwise. For illustration, consider what happens when you use parens after print in Python 2: the parens are treated like they would be in a mathematical expression — only there for the sake of order of operations. The parens effectively disappear when parsing.

Re: Making Python 3 more attractive

#132

Post by dvirsky »

aidos wrote: post #104
dvirsky wrote: post #49

Earlier quoted context omitted.

Most of this stuff is great and I'm actually looking forward to moving to py3k. But I've been looking forward for a few years now, though, and it seems like that will continue to for a while longer. The main problem for me remains dependencies. Python makes it so easy to integrate stuff via pip/easy_install, but that's a double edged sword in this case: Since there's such a huge abundance of great libraries for anyth…

Do you have a list of dependencies that are causing you the issues? When I did my migration (about 9 months ago) I found that there were a few dependencies that had been superseded by much better libraries. At the time there were a couple where I had to use a py3 branch, but no longer.

One of the most annoying ones is Thrift. But I just googled it and it seems like they are very close to supporting Python 3. A couple others - mysql-python, fabric, oauth2. These are the ones that are on the wall-of-shame. But I didn't test the entire dependency set.

Re: Making Python 3 more attractive

#133

Post by Leynos »

bufordsharkley wrote: post #52
plesner wrote: post #41

Making python 3 more attractive is not the solution, it's part of the problem. I can't use just python 3 because python 2 is still widely used. I can write code that works on both but now I'm using the worst of both worlds, and even worse I now have to test on both. And that'll last until python 2 goes away completely which, - when has a language ever gone away quickly? These aren't fun problems. Improving python 3,…

Removing the print statement is, to me, an extremely frustrating breaking change to make. If nothing else, I feel that backward compatibility should be given toward's a language's canonical "hello world" example.

It can't be that difficult to do a one-off `find . -type f -name '*.py' -print0 | xargs -0 grep 'print '`, change the print statements to functions and add `from __future__ import print_function` can it?

Re: Making Python 3 more attractive

#134

Post by rburhum »

qznc wrote: post #76
rburhum wrote: post #12

OK... so from a _practical_ perspective, can someone tell me why I should move to python 3? None of the arguments presented to switch are strong enough :-/

A practical perspective depends very much on your specific use case. Server programming? Scripting? Scientific computing? Games? Tooling?

I am honestly curious if there is a good argument for any of the examples you mentioned.

Re: Making Python 3 more attractive

#135

Post by cookiecaper »

ghshephard wrote: post #13
cookiecaper wrote: post #7

I don't think any of the things proposed will really drive conversion from Py2 to Py3. I don't think developers need to be excited about it, it just needs to be plausible. Python 3 has some significant momentum now (these talks seem overly negative about it). Developers are waiting for the signal from the enterprise Linux distributions that Py3 is "truly stable", i.e., they're waiting for it to be made the default Py…

Mercurial is a canary - if they see so much pain involved in moving from Py2 to Py3, and little reward, then that's representative of the overall ecosystem. Having people on older versions of the interpreter is a problem, because it divides the community in half when it comes to knowledge, skillset, capability, etc.. It also confuses outsiders who are looking at the situation, and don't understand which version they…

Mercurial is a large, complicated project, so it makes sense that they'd delay a backend upgrade like Py2->Py3 as long as they can get away with it. It's not representative of the overall ecosystem. That's like arguing that as long as "canaries" like Facebook don't see any reason to move to Ruby or Python for web dev, the rest of us might as well stay on PHP too. There's a large investment in the existing infrastructure that often can't be ignored no matter how compelling the features of the new platform are.

The differences between Py2 and Py3 are not substantial enough that it "divides the community in half" in any tangible fashion. Yes, it's possible new software may not take Py2 compatibility into account and you'll need to switch to Py3 to get new stuff, but that's been the plan all along, right?

183 of the 200 most-used libraries are Py3 compatible now, including major systems like SciPy and Django. It's not 2009 anymore, and we should stop talking like it is. Py3 is the way forward and the Python Foundation needs to quickly and firmly deconstruct any sign of flapping on that front if they hope to convert the remaining Py2 holdouts.

I believe it would be very damaging for the community if Python backpedaled and said "OK, we know you just spent 7 years investing in the Py3 platform and converting your apps and libs to work on it, but visible projects like Mercurial still don't like it so we decided it wasn't worth it anymore." People don't take time out of their day to make their voices heard unless they're already discontented about something. We shouldn't assume that everyone hates Py3 just because Py3 users are going about their business quietly.

Re: Making Python 3 more attractive

#136

Post by aidos »

dvirsky wrote: post #132
aidos wrote: post #104

Earlier quoted context omitted.

Do you have a list of dependencies that are causing you the issues? When I did my migration (about 9 months ago) I found that there were a few dependencies that had been superseded by much better libraries. At the time there were a couple where I had to use a py3 branch, but no longer.

One of the most annoying ones is Thrift. But I just googled it and it seems like they are very close to supporting Python 3. A couple others - mysql-python, fabric, oauth2. These are the ones that are on the wall-of-shame. But I didn't test the entire dependency set.

I think on the mysql front there are a few alternatives (I use postgres now - and if there was any way of going that route, I'd do that instead). I believe the pure python version is the popular choice these days [0].

I mentioned it because when I went through the process, I was looking for py3 support from my existing libraries and didn't consider swapping them out (as in, initially it didn't even occur to me).

In some cases I found far better libs that were more actively developed (eg I ended up using xlsxwriter for my excel stuff and it was way better than my previous solution).

[0] https://pypi.python.org/pypi/PyMySQL

ps I believe they like to call it "Wall of Superpowers" these days :)

Re: Making Python 3 more attractive

#137

Post by cookiecaper »

reidrac wrote: post #72
eeZi wrote: post #23

Reasons I am excited about Python 3: * "yield from" * Unicode support (I'm German and the clear distinction between bytes and unicode really makes my life easier) * function annotations (PyCharm interprets them and uses them for static type checking) * cleaned up stdlib (not only names, but also features) * asyncio Library support is very good nowadays, pretty much all of the important libraries are either ported to…

So far I've focused on making new projects both Python 2 and 3 compatible, but "new stuff" in Python 3 is not always available when: - Laptop running Ubuntu Trusty: Python 3.4 - Production servers with Debian Wheezy: Python 3.2 - Laptop running Fedora 20: 3.3.2 You don't usually install Python in Linux using upstream, you install the version provided by your distribution and unfortunately Python 3 has differences bet…

Python is actually much better than almost all equivalent languages in this. Consider that custom package managers like rvm/bundler, nvm/npm, etc., are considered must-haves for any kind of serious development on Ruby or Node, whereas use of virtualenv is still kind of seen as a "bonus" feature. The fact that Python is good enough to allow that demonstrates its robustness.

Stop using Python 2. All of the justifications I'm seeing in this thread are complete non-starters. If you want to use a 3.3 feature, install Python 3.3. Are you seriously suggesting that we revert to the problems of 2.x, discarding all the effort that's been dumped into Py3 compat over the last 7 years, because you don't want to install a software package? It's really common to need to add extra sources to a package manager for new versions of things, and it's also common to need to build your own packages. It shouldn't be that hard. Be grateful that at least there's a possibility you can use the system Python, since Ruby communities don't really have that luxury.

Re: Making Python 3 more attractive

#138

Post by ghshephard »

cookiecaper wrote: post #135
ghshephard wrote: post #13

Earlier quoted context omitted.

Mercurial is a canary - if they see so much pain involved in moving from Py2 to Py3, and little reward, then that's representative of the overall ecosystem. Having people on older versions of the interpreter is a problem, because it divides the community in half when it comes to knowledge, skillset, capability, etc.. It also confuses outsiders who are looking at the situation, and don't understand which version they…

Mercurial is a large, complicated project, so it makes sense that they'd delay a backend upgrade like Py2->Py3 as long as they can get away with it. It's not representative of the overall ecosystem. That's like arguing that as long as "canaries" like Facebook don't see any reason to move to Ruby or Python for web dev, the rest of us might as well stay on PHP too. There's a large investment in the existing infrastruct…

Don't get me wrong - I'm totally on board with Py3, I'm just saying for newcomers to the language, they hear, "Python 2, if you want to be compatible" and "Python 3, it's the future" - and sometimes, they just throw up their hands and say - "I have no idea what version I should use."

I think things will get better when operating systems start to default to Python3.

Re: Making Python 3 more attractive

#139

Post by panglott »

bufordsharkley wrote: post #60
raverbashing wrote: post #57

Earlier quoted context omitted.

Exactly this Why is changing 'print stuff' to 'print (stuff)' such a big deal? I think 2To3 solves a lot of print cases https://docs.python.org/2/library/2to3.html

The print function is clearly a better, more precise way to handle it, to be sure... But the print statement was one prominent, attractive way that Python was essentially pseudocode-- its removal seems an improvement from a pedantic sense, but one that seems to run contrary to convenience and (perhaps) the expectations of a beginner.

As a beginner, I ~hated~ the print statement. The print function had analogous syntax to all other functions, whereas the print statement always seemed to use some kludgy tricks.
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