简单了解Python3里的一些新特性

user = "Jane Doe"action = "buy"log_message = 'User {} has logged in and did an action {}.'.format(
 user,
 action)print(log_message)输出：User Jane Doe has logged in and did an action buy.

user = "Jane Doe"action = "buy"log_message = f'User {user} has logged in and did an action {action}.'print(log_message)输出: User Jane Doe has logged in and did an action buy.

from pathlib import Pathroot = Path('post_sub_folder')print(root)输出结果: post_sub_folder
path = root / 'happy_user'# 输出绝对路劲print(path.resolve())输出结果：/root/post_sub_folder/happy_user

def sentence_has_animal(sentence: str) -> bool:
 return "animal" in sentence
sentence_has_animal("Donald had a farm without animals")# True

from enum import Enum, autoclass Monster(Enum):
  ZOMBIE = auto()
  WARRIOR = auto()
  BEAR = auto()print(Monster.ZOMBIE)输出: Monster.ZOMBIE

for monster in Monster:
  print(monster)输出: Monster.ZOMBIE   Monster.WARRIOR   Monster.BEAR

import timedef fib(number: int) -> int:
  if number == 0: return 0
  if number == 1: return 1
  return fib(number-1) + fib(number-2)start = time.time()fib(40)print(f'Duration: {time.time() - start}s')# Duration: 30.684099674224854s

from functools import lru_cache@lru_cache(maxsize=512)def fib_memoization(number: int) -> int:
  if number == 0: return 0
  if number == 1: return 1
  return fib_memoization(number-1) + fib_memoization(number-2)start = time.time()fib_memoization(40)print(f'Duration: {time.time() - start}s')# Duration: 6.866455078125e-05s

head, *body, tail = range(5)print(head, body, tail)输出： 0 [1, 2, 3] 4py, filename, *cmds = "python3.7 script.py -n 5 -l 15".split()print(py)print(filename)print(cmds)输出：python3.7
   script.py   ['-n', '5', '-l', '15']first, _, third, *_ = range(10)print(first, third)输出： 0 2

class Armor:
  def __init__(self, armor: float, description: str, level: int = 1):
    self.armor = armor    self.level = level    self.description = description  def power(self) -> float:
    return self.armor * self.level
armor = Armor(5.2, "Common armor.", 2)armor.power()# 10.4print(armor)# <__main__.Armor object at 0x7fc4800e2cf8>

from dataclasses import dataclass@dataclassclass Armor:
  armor: float
  description: str
  level: int = 1
  def power(self) -> float:
    return self.armor * self.level
armor = Armor(5.2, "Common armor.", 2)armor.power()# 10.4print(armor)# Armor(armor=5.2, description='Common armor.', level=2)

sound/             Top-level package
   __init__.py        Initialize the sound package
   formats/         Subpackage for file format conversions
       __init__.py
       wavread.py
       wavwrite.py
       aiffread.py
       aiffwrite.py
       auread.py
       auwrite.py       ...
   effects/         Subpackage for sound effects
       __init__.py
       echo.py
       surround.py
       reverse.py       ...
   filters/         Subpackage for filters
       __init__.py
       equalizer.py
       vocoder.py
       karaoke.py

sound/             Top-level package
   __init__.py        Initialize the sound package
   formats/         Subpackage for file format conversions
       wavread.py
       wavwrite.py
       aiffread.py
       aiffwrite.py
       auread.py
       auwrite.py       ...
   effects/         Subpackage for sound effects
       echo.py
       surround.py
       reverse.py       ...
   filters/         Subpackage for filters
       equalizer.py
       vocoder.py
       karaoke.py