Guido on python3 for beginners

Chris Angelico rosuav at gmail.com
Thu Feb 18 02:27:59 EST 2016


On Thu, Feb 18, 2016 at 5:47 PM, Steven D'Aprano
<steve+comp.lang.python at 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


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