分享6个隐藏的python功能

The Zen of Python, by Tim Peters
Beautiful is better than ugly. 优美胜于丑陋
Explicit is better than implicit. 明了胜于晦涩
Simple is better than complex. 简单胜过复杂
Complex is better than complicated. 复杂胜过凌乱
Flat is better than nested.　　扁平胜于嵌套
Sparse is better than dense. 　间隔胜于紧凑

a = 5
# 可以这样
print(2 < a < 10)
# 也可以这样
print(10 > a <= 9)

True
True

a = 2
b = 3
print(a, b)
# 直接交换
a, b = b, a
print(a, b)

2 3
3 2

a = ['a', 'b', 'c', 'd', 'e']
for(int i = 0; i < len(a); i++):
print(a[i])

a = ['a', 'b', 'c', 'd', 'e']
# 对a的长度使用range生成一个序列，然后遍历
for i in range(len(a)):
print(a[i])

a
b
c
d
e

a = ['a', 'b', 'c', 'd', 'e']
# 对a的长度使用range生成一个序列，然后遍历
for i in enumerate(a):
print(i)
# 或者这样
for index, value in enumerate(a):
print(index, value)

(0, 'a')
(1, 'b')
(2, 'c')
(3, 'd')
(4, 'e')
0 a
1 b
2 c
3 d
4 e

for i in foo:
  if i == 0:
    break
else:
  print("i was never 0")

# 对每一个规则使用引号括起来
pattern = (
 "^"         # beginning of string
"M{0,4}"      # thousands - 0 to 4 M's
"(CM|CD|D" # hundreds - 900 (CM), 400 (CD), 0-300 (0 to 3 C's),
          #      or 500-800 (D, followed by 0 to 3 C's)
"(XC|XL|L" # tens - 90 (XC), 40 (XL), 0-30 (0 to 3 X's),
          #    or 50-80 (L, followed by 0 to 3 X's)
"(IX|IV|V" # ones - 9 (IX), 4 (IV), 0-3 (0 to 3 I's),
          #    or 5-8 (V, followed by 0 to 3 I's)
"$"         # end of string
 )
print(pattern)
# 然后bapattern放入对应的re匹配方法中。

^M{0,4}(CM|CD|D"htmlcode">

def seek_next_line(f):
for c in iter(lambda: f.read(1),'\n'):
pass


上面的代码中，从f中循环读入，如果碰到\n则结束读取。
其他的技巧像使用生成器表达式，利用拆包方法等等，之前都有说过，这里不再赘述。