[Python-ideas] Smoothing transition to Python 3

[tritium-list at sdamon.com]

> -----Original Message-----
> From: Python-ideas [mailto:python-ideas-bounces+tritium-
> list=sdamon.com at python.org] On Behalf Of Neil Schemenauer
> Sent: Friday, June 3, 2016 9:18 AM
> To: python-ideas at python.org
> Subject: [Python-ideas] Smoothing transition to Python 3
> 
...
 > - comparision with None, smaller than all other types

In a hypothetical python 2.8, the python 3 behavior would be in my backport
list...

> - comparision of distinct types: use Python 2 behavior (i.e. order
>   by type name)

...and this

> - mixing of unicode strings with byte strings: decode/encode
>   using latin-1

...and this
 
> - dict objects: make keys() items() values() return special sequence
>   that warns if iterated over multiple times or indexed as sequence

...and this.  In fact most of the things you list here are the GOOD ideas
that python 3 enforces that reduces bugs when avoided in python 2.

What would actually help the transition, in my world-view at least is 

* A bytes type like the string type in python 2 (*without implicit
conversion!*) There are too many real world use cases that the bytes type
makes painful, including anything dealing with networking.
* an alias to the string type named 'unicode' (this just makes polyglot a
whole heck of a lot less stressful... yes I do this myself, it's annoying,
if it was there by default, like bytes is in 2.7, it would make life a lot
easier.  One just never just never references `str`)
* a "magic" mapping from old to new module names.  In my experience, this is
actually a bigger pain than it looks.

I had discussed, informally on IRC, the concept of building a hypothetical
'final version of python 2' that is, in fact, libpython3 with a python2
parser and shims in front of it.  The general response was the theme of the
entire python 3 transition story:  "I don't see the value added."  This was
in response to more than just my crazy idea, but to the entire process and
existence of python 3.  I cannot disagree; the entire situation is a lot of
effort for very little value added.  Maybe a 'more compatible python 3' is a
solution, maybe not.

I have seen the pypi download numbers[1], and it is not encouraging for
python 3; python 2 outstrips python 3 by a factor of 10 in terms of package
downloads on linux, and a factor of 6 on mac.  The only platform where
python 3 has a real story against 2 is windows.

If python 3 really is to be the future, a lot more needs to be done to bring
the vast majority of users on board.  Telling them "Just port your code" is
not good enough.

 [1] https://s.caremad.io/WPVkP3Ruhg/ (query:
https://bpaste.net/show/56443668b83f)