Re: Stop writing Python 4 incompatible code

From	Terry Reedy <tjreedy@udel.edu>
Newsgroups	comp.lang.python
Subject	Re: Stop writing Python 4 incompatible code
Date	2016-01-14 00:45 -0500
Message-ID	<mailman.133.1452750375.13488.python-list@python.org> (permalink)
References	<5695fd0e$0$11119$c3e8da3@news.astraweb.com> <0529e7d6-0de1-4e38-9a19-2b5ed1ecc39f@googlegroups.com> <mailman.110.1452702751.13488.python-list@python.org> <5696e77e$0$1597$c3e8da3$5496439d@news.astraweb.com> <5d7a5bb1-f229-4755-a0bf-dd3ad9d99fba@googlegroups.com>

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On 1/13/2016 8:02 PM, Rick Johnson wrote:
> and a leader who lost his cushy job at Google

Unless you have access to facts that I do not, 'lost' is impolite 
speculation. But lets move on.

I have a contrary hypothesis based on the facts quoted below.  As far as 
I know, Google is somewhat stuck on 2.7.  Dropbox, on the other, is 
migrating to modern 3.x Python (see below).  Guido wants the world to do 
this, so he moved to a company where he can help make this practical, by 
helping to work out some of the practical details of how to do so, and 
then share them with the rest of the Python community.

On Jan 8, 6 days ago, Guido posted on python-idea "Proposal to extend 
PEP 484 (gradual typing) to support Python 2.7"

"At Dropbox we're trying to be good citizens and we're working towards 
introducing gradual typing (PEP 484) into our Python code bases (several 
million lines of code). However, that code base is mostly still Python 
2.7 and we believe that we should introduce gradual typing first and 
start working on conversion to Python 3 second (since having static 
types in the code can help a big refactoring like that).

Since Python 2 doesn't support function annotations we've had to look 
for alternatives. We considered stub files, a magic codec, docstrings, 
and additional `# type:` comments. In the end we decided that `# type:` 
comments are the most robust approach. We've experimented a fair amount 
with this and we have a proposal for a standard."

A few days later, in the absence of objection to the proposed comment 
syntax, he added the proposal.  Not mentioned in the quote is that mypy 
will support the new comments for static analysis.  2.x interpreters 
will happily ignore then.

If Dropbox comment-annotates a public 2.x package, it can contribute the 
work back for the use of others.  Google, on the other hand, decided to 
support annotation in 2.7 creating a custom 2.7 interpreter than will 
ignore them.  Any code annotated by Google will be useless on standard 
interpreters without being run through a converter.

-- 
Terry Jan Reedy

Thread

Stop writing Python 4 incompatible code Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-01-13 18:30 +1100
  Re: Stop writing Python 4 incompatible code sjmsoft@gmail.com - 2016-01-13 06:21 -0800
    Re: Stop writing Python 4 incompatible code Random832 <random832@fastmail.com> - 2016-01-13 11:25 -0500
      Re: Stop writing Python 4 incompatible code Steven D'Aprano <steve@pearwood.info> - 2016-01-14 11:10 +1100
        Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-13 22:40 -0200
          Re: Stop writing Python 4 incompatible code Steven D'Aprano <steve@pearwood.info> - 2016-01-14 12:02 +1100
            Re: Stop writing Python 4 incompatible code Michael Torrie <torriem@gmail.com> - 2016-01-13 18:24 -0700
            Re: Stop writing Python 4 incompatible code Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-01-13 21:39 -0500
            Re: Stop writing Python 4 incompatible code Gene Heskett <gheskett@wdtv.com> - 2016-01-13 21:59 -0500
            Re: Stop writing Python 4 incompatible code Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-01-14 07:41 -0500
            Re: Stop writing Python 4 incompatible code Peter Otten <__peter__@web.de> - 2016-01-14 14:43 +0100
            Re: Stop writing Python 4 incompatible code "D'Arcy J.M. Cain" <darcy@VybeNetworks.com> - 2016-01-14 08:47 -0500
            Re: Stop writing Python 4 incompatible code Peter Otten <__peter__@web.de> - 2016-01-14 16:32 +0100
            Re: Stop writing Python 4 incompatible code "D'Arcy J.M. Cain" <darcy@VybeNetworks.com> - 2016-01-14 10:47 -0500
            Re: Stop writing Python 4 incompatible code Peter Otten <__peter__@web.de> - 2016-01-14 17:52 +0100
            Re: Stop writing Python 4 incompatible code Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-01-15 16:08 +1300
              Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-15 15:56 +1100
                Re: Stop writing Python 4 incompatible code Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-01-16 10:02 +1300
              Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-15 09:40 -0200
          Re: Stop writing Python 4 incompatible code Robin Koch <robin.koch@t-online.de> - 2016-01-15 19:29 +0100
            Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-15 16:43 -0200
        Re: Stop writing Python 4 incompatible code Terry Reedy <tjreedy@udel.edu> - 2016-01-13 19:53 -0500
        Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-13 17:02 -0800
          Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-14 12:29 +1100
          Re: Stop writing Python 4 incompatible code Michael Torrie <torriem@gmail.com> - 2016-01-13 19:11 -0700
            Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-13 18:51 -0800
              Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-14 14:08 +1100
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-13 19:29 -0800
                Re: Stop writing Python 4 incompatible code Michael Torrie <torriem@gmail.com> - 2016-01-13 22:18 -0700
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-14 07:30 -0800
                Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-15 04:41 +1100
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-14 10:40 -0800
                Re: Stop writing Python 4 incompatible code <paul.hermeneutic@gmail.com> - 2016-01-14 13:16 -0700
                Re: Stop writing Python 4 incompatible code Steven D'Aprano <steve@pearwood.info> - 2016-01-15 09:04 +1100
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-14 15:16 -0800
                Re: Stop writing Python 4 incompatible code Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-01-14 19:16 +1100
                Re: Stop writing Python 4 incompatible code wxjmfauth@gmail.com - 2016-01-14 01:37 -0800
          Re: Stop writing Python 4 incompatible code Terry Reedy <tjreedy@udel.edu> - 2016-01-14 00:45 -0500
            Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-14 07:52 -0800
              Re: Stop writing Python 4 incompatible code Ian Kelly <ian.g.kelly@gmail.com> - 2016-01-14 15:52 -0700
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-14 15:55 -0800
                Re: Stop writing Python 4 incompatible code Emile van Sebille <emile@fenx.com> - 2016-01-15 06:52 -0800
                Re: Stop writing Python 4 incompatible code Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-01-16 09:49 +1300
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-15 14:34 -0800
                Re: Stop writing Python 4 incompatible code Rick Johnson <rantingrickjohnson@gmail.com> - 2016-01-15 13:45 -0800
                Re: Stop writing Python 4 incompatible code William Ray Wing <wrw@mac.com> - 2016-01-15 12:02 -0500
                Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-15 16:09 -0200
                Re: Stop writing Python 4 incompatible code Alister <alister.ware@ntlworld.com> - 2016-01-15 18:46 +0000
                Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-15 16:55 -0200
                Re: Stop writing Python 4 incompatible code Alister <alister.ware@ntlworld.com> - 2016-01-16 14:41 +0000
                Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-16 12:48 -0200
                Re: Stop writing Python 4 incompatible code paul.hermeneutic@gmail.com - 2016-01-16 09:08 -0700
                Re: Stop writing Python 4 incompatible code William Ray Wing <wrw@mac.com> - 2016-01-16 13:00 -0500
                Re: Stop writing Python 4 incompatible code Michael Torrie <torriem@gmail.com> - 2016-01-16 12:26 -0700
                Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-17 13:43 +1100
                Re: Stop writing Python 4 incompatible code William Ray Wing <wrw@mac.com> - 2016-01-15 13:49 -0500
                Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-15 16:53 -0200
                Re: Stop writing Python 4 incompatible code Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-01-15 20:58 +0000
                Re: Stop writing Python 4 incompatible code Christopher Reimer <christopher_reimer@icloud.com> - 2016-01-15 14:09 -0800
                Re: Stop writing Python 4 incompatible code Christopher Reimer <christopher_reimer@icloud.com> - 2016-01-16 20:51 -0800
    Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-14 03:38 +1100
  Re: Stop writing Python 4 incompatible code Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-01-14 10:38 +1300
    Re: Stop writing Python 4 incompatible code Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-01-13 19:46 -0200
  Re: Stop writing Python 4 incompatible code BartC <bc@freeuk.com> - 2016-01-14 01:02 +0000
    Re: Stop writing Python 4 incompatible code Chris Angelico <rosuav@gmail.com> - 2016-01-14 12:21 +1100
      Re: Stop writing Python 4 incompatible code BartC <bc@freeuk.com> - 2016-01-14 01:49 +0000

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