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Re: Guido on python3 for beginners

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In Python 3, I don't required to teach followings to newbies.

1. Don't do `class Foo:`, do `class Foo(object):`.
2. Don't do `isinstance(x, int)`, do `isinstance(x, (int, long))`.
3. Don't return non-ASCII string from `__repr__`, otherwise UnicodeError
   happens in logging and you will lost your important log.
4. Use %r instead of %s in logging to avoid UnicodeError when __str__
returns non ASCII strings.

I think there are many pitfalls fixed in Python 3 other than above.
Python 3 is far easier to teach and review code than Python 2.


On Thu, Feb 18, 2016 at 4:27 PM, Chris Angelico <rosuav@gmail.com> wrote:

> On Thu, Feb 18, 2016 at 5:47 PM, Steven D'Aprano
> <steve+comp.lang.python@pearwood.info> wrote:
> > There are more features in Python 3, so in that trivial sense of "more to
> > learn", I suppose that it is objectively correct that it is harder to
> learn
> > than Python 2. But I don't think the learning curve is any steeper. If
> > anything, the learning curve is ever-so-slightly less steep.
>
> Let's see... changes in Py3.
>
> 1) Division of two integers now yields a float instead of flooring.
> For someone fresh to programming, that's a Py3 advantage, although it
> can cause surprises elsewhere. But since 1.0==1, it's not going to be
> a problem for a new programmer. Advantage: Py3.
>
> 2) Strings are Unicode text, and files etc may need to have their
> encodings declared. Definitely causes some issues in ASCII-only
> situations, where a lot of other languages (notably including PHP, for
> the people building web sites) let you be sloppy. Advantage: Py3 if
> you speak any language other than English; otherwise Py2 in the very
> short term, neither in the medium term, and most definitely Py3 in the
> long term (no more "funny characters break my program" errors long
> after deployment).
>
> 3) Laziness. When you explain to someone what the range() function
> does, Py2 makes a list, but Py3 makes... a range. It doesn't really
> answer the question at all. When you ask Py2 for a dictionary's
> keys/values, you get a list; Py3 gives you a thing that mostly acts
> like a list, only it isn't. If you map a function over a list, you get
> back a lazy thing that will eventually call that function. Py2 often
> has less levels of indirection, ergo less things to try to explain.
> Advantage: Py2; the benefits (lower memory usage, etc) aren't
> significant to new users.
>
> 4) Exception chaining. You get more information when errors cascade.
> Advantage: Py3, easily and without any question.
>
> 5) print statement/function. Py3 forces you to put parentheses on it,
> which is no different from C's printf() or Pike's write() or any
> number of other languages where console I/O needs no language support.
> Maybe a tiny TINY advantage to Py2 in the short term, but as soon as
> you introduce the less basic features, keyword arguments are way
> better than the magic syntax the statement needs. (Also, trying to
> explain the interaction between the print statement's "soft space" and
> other console I/O is not easy.) By the time you've really learned the
> language, the advantage belongs to Py3.
>
> 6) The fact that the name "python" may not invoke the interpreter you
> want. Advantage: Py2, if any; there'll be times when they're on par,
> but Py3 never comes out ahead.
>
> 7) Whether or not the interpreter comes pre-installed on your system.
> As of a few years ago, that was a clear advantage to Py2 (most systems
> would ship with both, or neither, or Py2 only), but that's shifting.
> It's only a small difference, though; on Windows, you generally get
> nothing, and on any system with a decent package manager, you should
> be able to request either version with ease.
>
> It's actually a pretty tough call. Most of the Py3 advantages aren't
> for the absolute beginner; it's not easier to write "Hello, world" in
> Py3, and aside from the change to integer division, most of the
> changes won't benefit small-to-medium scripts either. The biggest
> advantage (Unicode by default) really only shows itself by sparing you
> hassles later on - it's not going to make your life easier in the
> short term, ergo it's not going to make the language easier to learn.
> Py3 isn't so much easier as _better_. There are specific situations
> where it's massively better, but for the most part, they're about on
> par.
>
> ChrisA
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
INADA Naoki  <songofacandy@gmail.com>

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  Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO John Ladasky <john_ladasky@sbcglobal.net> - 2016-02-02 22:02 -0800
    Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Bernardo Sulzbach <mafagafogigante@gmail.com> - 2016-02-03 04:07 -0200
    Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Rick Johnson <rantingrickjohnson@gmail.com> - 2016-02-06 12:54 -0800
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO INADA Naoki <songofacandy@gmail.com> - 2016-02-07 12:02 +0900
        Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-02-07 16:59 +1100
          Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Paul Rubin <no.email@nospam.invalid> - 2016-02-06 23:04 -0800
            Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Rustom Mody <rustompmody@gmail.com> - 2016-02-06 23:31 -0800
              Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Paul Rubin <no.email@nospam.invalid> - 2016-02-06 23:51 -0800
                Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Chris Angelico <rosuav@gmail.com> - 2016-02-07 18:58 +1100
                Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Jason Swails <jason.swails@gmail.com> - 2016-02-08 10:20 -0500
            Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Christian Gollwitzer <auriocus@gmx.de> - 2016-02-07 08:44 +0100
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Chris Angelico <rosuav@gmail.com> - 2016-02-07 14:06 +1100
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Ian Kelly <ian.g.kelly@gmail.com> - 2016-02-08 08:40 -0700
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Random832 <random832@fastmail.com> - 2016-02-08 10:44 -0500
        Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO wxjmfauth@gmail.com - 2016-02-09 01:15 -0800
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Chris Angelico <rosuav@gmail.com> - 2016-02-09 02:46 +1100
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Random832 <random832@fastmail.com> - 2016-02-08 10:53 -0500
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Chris Warrick <kwpolska@gmail.com> - 2016-02-08 18:48 +0100
      Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO John Ladasky <john_ladasky@sbcglobal.net> - 2016-02-11 23:51 -0800
        Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Rick Johnson <rantingrickjohnson@gmail.com> - 2016-02-15 18:02 -0800
          Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Chris Angelico <rosuav@gmail.com> - 2016-02-16 13:30 +1100
          Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO John Ladasky <john_ladasky@sbcglobal.net> - 2016-02-15 21:24 -0800
            Guido on python3 for beginners Rustom Mody <rustompmody@gmail.com> - 2016-02-17 00:51 -0800
              Re: Guido on python3 for beginners Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-02-18 17:47 +1100
                Re: Guido on python3 for beginners Ben Finney <ben+python@benfinney.id.au> - 2016-02-18 17:57 +1100
                Re: Guido on python3 for beginners Paul Rubin <no.email@nospam.invalid> - 2016-02-17 22:59 -0800
                Re: Guido on python3 for beginners "Sven R. Kunze" <srkunze@mail.de> - 2016-02-18 22:37 +0100
                Re: Guido on python3 for beginners Random832 <random832@fastmail.com> - 2016-02-18 02:00 -0500
                Re: Guido on python3 for beginners Chris Angelico <rosuav@gmail.com> - 2016-02-18 18:27 +1100
                Re: Guido on python3 for beginners John Ladasky <john_ladasky@sbcglobal.net> - 2016-02-18 12:22 -0800
                Re: Guido on python3 for beginners INADA Naoki <songofacandy@gmail.com> - 2016-02-18 17:00 +0900
                Re: Guido on python3 for beginners Terry Reedy <tjreedy@udel.edu> - 2016-02-18 03:40 -0500
                Re: Guido on python3 for beginners Steven D'Aprano <steve@pearwood.info> - 2016-02-20 18:59 +1100
                Re: Guido on python3 for beginners Chris Angelico <rosuav@gmail.com> - 2016-02-18 20:57 +1100
                Re: Guido on python3 for beginners Cem Karan <cfkaran2@gmail.com> - 2016-02-18 05:57 -0500
                Re: Guido on python3 for beginners Chris Angelico <rosuav@gmail.com> - 2016-02-18 22:07 +1100
                Re: Guido on python3 for beginners Rustom Mody <rustompmody@gmail.com> - 2016-02-18 04:25 -0800
                Re: Guido on python3 for beginners Random832 <random832@fastmail.com> - 2016-02-18 10:51 -0500
                Re: Guido on python3 for beginners Steven D'Aprano <steve@pearwood.info> - 2016-02-19 12:17 +1100
                Re: Guido on python3 for beginners Rustom Mody <rustompmody@gmail.com> - 2016-02-18 19:39 -0800
                Re: Guido on python3 for beginners Steven D'Aprano <steve@pearwood.info> - 2016-02-20 13:36 +1100
                Re: Guido on python3 for beginners Larry Hudson <orgnut@yahoo.com> - 2016-02-20 00:37 -0800
                Re: Guido on python3 for beginners Grant Edwards <invalid@invalid.invalid> - 2016-02-19 15:06 +0000
                Re: Guido on python3 for beginners Rustom Mody <rustompmody@gmail.com> - 2016-02-18 19:32 -0800
                Re: Guido on python3 for beginners Matt Wheeler <m@funkyhat.org> - 2016-02-18 16:44 +0000
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            Re: [STORY-TIME] THE BDFL AND HIS PYTHON PETTING ZOO Chris Angelico <rosuav@gmail.com> - 2016-02-19 08:54 +1100
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