The Case Against Python 3

Which is exactly opposite for c++11 - it doesn't break backwards compatibility, but I really want those new features. I think if it broke backwards compatibility, I'd still switch to the new c++.

At work we use py2 and c++11...

> Not In Your Best Interests

I say what's in my best interest and py3 fixed a lot of issues for me. I'm happy with the upgrade and dropped py2 for new projects this year.

> No Working Translator

A flawless translator is simply not possible. 2to3 is the best effort idea. At some point you'll run into `def f(x): return x[0]` and without doing a full program static analysis you won't be able to say what's the right translation. You have to do it manually where needed.

> Difficult To Use Strings

I understand that the py2's "just works" strings are easier. But at the same time, having a non-ascii name I know that most applications "just work" simply because nobody actually tested them outside of ascii set. Py3 doesn't explode on encoding for fun - it basically says: you made an assumption that kind of worked so far by accident, but now you need to say explicitly what you want to do. I think it's a good thing, even if it takes people time to adjust.

> Core Libraries Not Updated

I don't even know what he means. This really needs an example, or it's just a meaningless rant.

> Purposefully Crippled 2to3 Translator

As above. Some things are just not possible to translate without knowing what the programmer meant. Some things in py2 strings happened to work a bit "by accident" and simply won't work in py3 for good reasons. For example py2 code:

    In [1]: "abc".encode('ascii').encode('ascii')
    Out[1]: 'abc'

Great things, IMHO. Now that the painful changes of 2 to 3 are done (or nearly so), recent releases have focused on incremental and steady progress. Take a look at the "What's New" documents:

https://docs.python.org/3.6/whatsnew/3.6.html https://docs.python.org/3/whatsnew/3.5.html

There is a lot of great stuff there without ripping up the world and breaking all your programs. For example, the new compact dict implementation in 3.6 is a great improvement. All Python programs can potentially benefit from the memory use reduction. Bug fixes and improvements to library code are great.

The transition from 2.x to 3.x was not handled well. The core Python team should have focused much more on making transitioning code easier. Allowing code that can easily run in both 2.x and 3.x (with suitable shims like 'six') should have been a focus early on. Disallowing 'u' prefix on strings in 3.x is an example of a serious mistake. The argument of keeping 3.x pure was wrong. It is much more important to make transition easier rather than making 3.x extremely pure. That's something that C++ has got right, although maybe they went too far the other way.

My small contribution to transitioning 2.x to 3.x is "ppython". See my github repo:

https://github.com/nascheme/ppython

Now that I've been programming in Python 3 for a few months, I find it pleasant. Writing programs that handle Unicode text correctly is easier. For small programs, it is easy to make them run under either Python 2 or 3.