Migrating to Python 3 with pleasure

Post by crdoconnor » Mon, Feb 05, 2018, 9:50 AM UTC

dbcurtis wrote: post #73

thijsvandien wrote: post #22

Earlier quoted context omitted.

It was recently decided that as of 3.7 it will be. (Source: https://mail.python.org/pipermail/python-dev/2017-December/1... )

Hmmmmmm.... that makes it hard for other implementations. CPython isn't the whole of the Python world. Requirements like that can be problematic for implementations like Micropython, for instance.

Post by StavrosK » Mon, Feb 05, 2018, 9:53 AM UTC

eesmith wrote: post #113

StavrosK wrote: post #112

Earlier quoted context omitted.

A section called "CPython implementation detail" looks like the very antithesis of a guarantee, to me.

My apologies. I looked for the answer I knew was there, and quoted the wrong section because it matched what I was looking for. I should have quoted the next section: > If items(), keys(), values(), iteritems(), iterkeys(), and itervalues() are called with no intervening modifications to the dictionary, the lists will directly correspond. Curiously, the "Dictionary view objects" section at https://docs.python.org/2.7…

Post by agumonkey » Mon, Feb 05, 2018, 9:58 AM UTC

est wrote: post #39

re wrote: post #32

I've been toying around with Python 3 and using it for most of my personal/hack projects, but I somehow missed the unpacking improvements: https://www.python.org/dev/peps/pep-0448/ In particular, being able to create an updated copy of a dict with a single expression is pretty cool: return {**old, 'foo': 'bar'} # Old way new = old.copy new['foo'] = ['bar'] return new

return {**old, 'foo': 'bar'} # Old way return dict(old, foo='bar') Not much difference if you ask me.

Post by agumonkey » Mon, Feb 05, 2018, 10:00 AM UTC

miracle2k wrote: post #33

re wrote: post #32

I've been toying around with Python 3 and using it for most of my personal/hack projects, but I somehow missed the unpacking improvements: https://www.python.org/dev/peps/pep-0448/ In particular, being able to create an updated copy of a dict with a single expression is pretty cool: return {**old, 'foo': 'bar'} # Old way new = old.copy new['foo'] = ['bar'] return new

My mind is blown. Ever since JavaScript added this, I've been wanting it in Python... and somehow it was there all along. It works for lists too! [*a, *b, *c]

Post by sethgecko » Mon, Feb 05, 2018, 10:03 AM UTC

jstimpfle wrote: post #10

StavrosK wrote: post #9

Earlier quoted context omitted.

Dicts never had an iteration order, though. If you relied on dicts iterating in order, you were kind of asking for it.

I believe newer Python versions have at least deterministic iteration order (correct me if I'm wrong), while some previous ones had a non-deterministic one (non-deterministic between mutiple invocations of the interpreter). But there is also OrderedDict which iterates in assignment order.