#131 Python 3 has issues (over on GitHub)
Python Bytes - Podcast tekijän mukaan Michael Kennedy and Brian Okken - Maanantaisin
Kategoriat:
Sponsored by DigitalOcean: pythonbytes.fm/digitalocean
Brian #1: PEP 581 (Using GitHub issues for CPython) is accepted
- PEP 581
- The email announcing the acceptance.
- “The migration will be a large effort, with much planning, development, and testing, and we welcome volunteers who wish to help make it a reality. I look forward to your contributions on PEP 588 and the actual work of migrating issues to GitHub.” — Barry Warsaw
Michael #2: Replace Nested Conditional with Guard Clauses
- Deeply nested code is problematic (does it have deodorant — err comments?)
- But what can you do? Guard clauses!
- See Martin Fowler’s article and this one.
# BAD!
def checkout(user):
shipping, express = [], []
if user is not None:
for item in user.cart:
if item.is_available:
shipping.append(item)
if item.express_selected:
express.append(item)
return shipping, express
# BETTER!
def checkout(user):
shipping, express = [], []
if user is None:
return shipping, express
for item in user.cart:
if not item.is_available:
continue
shipping.append(item)
if item.express_selected:
express.append(item)
return shipping, express
Brian #3: Things you’re probably not using in Python 3 – but should
- Vinko Kodžoman
- Some of course items:
- Some I’m warming to:
- type hinting
- And those I’m really glad for the reminder of:
- enumerations
from enum import Enum, auto
class Monster(Enum):
ZOMBIE = auto()
WARRIOR = auto()
BEAR = auto()
print(Monster.ZOMBIE)
# Monster.ZOMBIE
- built in lru_cache: easy memoization with the
functools.lru_cache
decorator.
@lru_cache(maxsize=512)
def fib_memoization(number: int) -> int:
...
- extended iterable unpacking
>>> head, *body, tail = range(5)
>>> print(head, body, tail)
0 [1, 2, 3] 4
>>> py, filename, *cmds = "python3.7 script.py -n 5 -l 15".split()
>>> cmds
['-n', '5', '-l', '15']
>>> first, _, third, *_ = range(10)
>>> first, third
(0, 2)
Michael #4: The Python Arcade Library
- Arcade is an easy-to-learn Python library for creating 2D video games. It is ideal for people learning to program, or developers that want to code a 2D game without learning a complex framework.
- Minesweeper games, hangman, platformer games in general.
- Check out Sample Games Made With The Arcade Library too
- Includes physics and other goodies
- Based on OpenGL
Brian #5: Teaching a kid to code with Pygame Zero
- Matt Layman
- Scratch too far removed from coding.
- Using Mu to simplify coding interface.
- comes with a built in Python.
- Pygame Zero preinstalled
- “[Pygame Zero] is intended for use in education, so that teachers can teach basic programming without needing to explain the Pygame API or write an event loop.”
- Initial 29 line game taught:
- naming things and variables
- mutability and fiddling with “constants” to see the effect
- functions and side effects
- state and time
- interactions and mouse events
- Article also includes some tips on how to behave as the adult when working with kids and coding.
Michael #6: Follow up on GIL / PEP 554
- Has the Python GIL been slain? by Anthony Shaw
- multithreading in CPython is easy, but it’s not truly concurrent, and multiprocessing is concurrent but has a significant overhead.
- Because Interpreter state contains the memory allocation arena, a collection of all pointers to Python objects (local and global), sub-interpreters in PEP 554 cannot access the global variables of other interpreters.
- the way to share objects between interpreters would be to serialize them and use a form of IPC (network, disk or shared memory). All options are fairly inefficient
- But: PEP 574 proposes a new pickle protocol (v5) which has support for allowing memory buffers to be handled separately from the rest of the pickle stream.
- When? Pickle v5 and shared memory for multiprocessing will likely be Python 3.8 (October 2019) and sub-interpreters will be between 3.8 and 3.9.
Extras
Brian:
- PyCon 2019 videos are available
- So grateful for this. Already watched a couple, including Ant’s awesome talk about complexity and wily.
- pytest and hypothesis show up in the new Pragmatic Programmer book.
Michael:
- 100 Days of Web course is out!
- Effective PyCharm book
- New release of our Android and iOS apps.
Jokes
- MK → Waiter: Would you like coffee or tea? Programmer: Yes.