overall - very less reason to consider Py3 at all. Performance would have been one - if there were a comparison between gevent and asyncio.
Unicode? Not having to deal with encoding all over the place has been well worth switch to Python 3. If performance is a a huge issue, I honestly don't know why you would stay on Python (regardless of version)
I wouldn't want to switch back to Python 2.7 is I can avoid it. There's honestly no reason not to go with 3.4 or 3.5 at this point, unless you happen to have a large Python 2 code base.
> do_something(*some_args, *some_more_args)
I see this a lot. That one doesn't care of performance that much to switch to, say, C++ or Go, doesn't mean one is OK with regressions to what they currently use.
But in large I agree. 3 hasn't provided enought of a carrot and 2 hasn't been enough of a pain for many people to want to switch. Especially when it comes to existing stable code bases. For new development, yes, many can and should pick Python 3. But if say Python 3 brought even a 20% speed improvement overwall, the move would have been a lot faster.
I find people are ok with accepting some breakages due to re-writes if either existing stuff is very broken, or new stuff is so much better.
I have zero problems with Python 3 per se - but when the vast majority of the ecosystem is on Py2 and there is no difference in performance... then I see no reason to consider any breakages.
As a result, guys like you who are thinking rationally become the problem for being 'lazy' (acting in your own best interests which is exactly what everyone is doing) and are the enemy. People, especially newcomers, get tired of waiting for Python2 to 'die' and instead of put the onus on those who made the mistakes with Python3 (they've stuck it out, refusing to correct their own mistakes because that's more work), it becomes twisted and you are now the problem in their mind. Even though you were probably a part of what made Python successful to begin with. Amazing how that pans out, right?
Usually these illusions go away once a full time job is found, there are some but the vast majority are companies with big Python2 codebases that have features to deliver. If they move services anywhere from CPython it's to PyPy for the performance gain.
Very helpful for porting: http://python-future.org
- Python 2 will be EOL in 2020, that's four years
- vastly improved Unicode support
- a number new libraries are Python 3 only
- asyncio and the new async syntax
- exception chaining (!)
- type annotations
- lots of improvements all over the placeI wont dispute you on any other aspects - except two. have you tried using gevent versus asyncio ? gevent is running in production at several of the largest API services in the world. Asyncio is not yet deployed at this scale.
Second about new libraries being python 3 only - really dispute that. In fact its the other way around. For example, the brand new Tensorflow library (which google uses in production for its own AI) was released on Python 2 only .. and Python 3 support was later patched in. This is the case with every new library of consequence that I'm seeing.
At some point, the opportunity cost of staying with Python 2.7 is higher than the one-time effort of porting everything to Python 3, so companies will move. Especially the likes of Google and Dropbox.
gevent vs. asyncio - sure, gevent is more mature. But asyncio is undoubtedly the better/nicer API. asyncio's explicit await syntax is much nicer than gevent's implicit monkey-patching, which makes it harder to reason about the code.
Tensorflow isn't really a new library, it was only recently open sourced.
As for Python 3-only libraries:
- https://pypi.python.org/pypi?:action=browse&show=all&c=595
Also note that Django will drop Python 2 support in time with the Python 2 EOL: https://www.djangoproject.com/weblog/2015/jun/25/roadmap/
Also, many new Python-based open source projects are Python 3 only.
There's a cost to maintain, and that's why PSF is moving to 3. I'm sure if Google and/or Dropbox would pay, PSF might continue maintenance[1].
Anyway the issue here is that you won't get any new features in python 2.7, and that already happened last year, currently python 2 only gets security fixes.
> have you tried using gevent versus asyncio ? gevent is running in production at several of the largest API services in the world. Asyncio is not yet deployed at this scale.
Both of them are available on python 3. On python 2 you can't chose. AsyncIO strength is that it is integrated into the language. Especially in 3.5 you have a new syntax to use it, no need to install new libraries, no need to compile anything. No monkey patching. Also AsyncIO is more generalized and could be adapted to other tasks, not necessarily for asynchronous calls.
[1] In fact surely Red Hat will continue to maintain it until 2027 since they decided to ship it with Red Hat 7, but question is whether they will share it with general users, or will they only provide it to paying customers.
Running out the clock on waiting for library support to become mostly python 3 is inevitable, but so far has been slower than molasses.