Pythonic

a, b = b, a # 先生成一个元组(tuple)对象，然后unpack

a,*c,d = [1,2,3,4,5]

if 0 in [1,2,3]: print(1)

''.join(['a','b','c'])

for key in my_dict: # my_dict[key] ... 
# 只有当循环中需要更改key值的情况下，我们需要使用 my_dict.keys()
# 生成静态的键值列表。

if key in my_dict: #...do something with d[key]

a = {} # update or create
for (b,c) in ((1,2),(2,3)):
    a[b] = a.get(b,0) # if b not in a: a[b]=0
    # a.setdefault(b,0)
print(a)

if ['a']: print(1)

for idx,item in enumerate('a b c'.split()): print(idx,item)

[print(i) for i in range(10) if i%2==0]

a = (i for j in range(200) if j%3==0 \
 for i in range(100) if i%3==0)
for b in a: print(b)

from itertools import product
[print(x,y,z) for x,y,z in product([1,2],[3,4],[5,6])]

def fab(max): 
    n, a, b = 0, 0, 1 
    while n < max: 
        yield b # print(b)
        a, b = b, a + b 
        n = n + 1
for n in fab(5):  print(n)

print(any([False,False]),all([True,True]))

class Goods(object):
  def __init__(self):  
    self.price = 100  # 原价
    self.discount = 0.8 # 折扣
 
  def get_price(self):
    # 实际价格 = 原价 * 折扣
    new_price = self.price * self.discount
    return new_price
 
  def set_price(self, value):
    self.price = value
 
  def del_price(self):
    del self.price
   # 获取    设置     删除    描述文档
  PRICE = property(get_price, set_price, del_price, '价格属性描述...')
 # 使用此方式设置
  
obj = Goods()
print(obj.PRICE)    # 获取商品价格
obj.PRICE = 200  # 修改商品原价
print(obj.PRICE)
del obj.PRICE   # 删除商品原价

with open("some_file.txt") as f: data = f.read()

import threading
lock = threading.Lock()
with lock: # 互斥操作...
# lock.acquire()
# try: # 互斥操作...
# finally: lock.release()

# str.rpartition()
print('str.rpartition','django.contrib.db'.rpartition(".")[-2:])

# str.isidentifier()
print('obj.isidentifier() is string','django'.isidentifier(),'0'.isidentifier())

# str.replace(a,b)
print('replaced'.replace("d",""))

# str.split(a)
print('split split'.split(" "))

class Test:
    a = None
    def __init__(self): self.a = True
    def __repr__(self): return '__repr__ return class'
    def __str__(self): return '__str__ packed repr for endusers'
    #
    def hasattr(self): return(hasattr(self,'a'),hasattr(self,'b'))
    @property
    def method_with_property(self): return 'method_with_property'
    def method_without_property(self): return 'method_without_property()'

# class >> __new__
test = object.__new__(Test)

# class >>  __repr__ >> __str__
print(test)
print(test.__repr__())
print(test.__str__())

# class >> getattr(self,'a')
print('getattr a:%s' % getattr(test,'a'))
# class >> hasattr(self,'b')
print('hasattr b:%s' % hasattr(test,'b'))

# class >> __init__ >> __dict__
print('__dict__',test.__dict__,test.a)
test.__init__()
print('__dict__',test.__dict__,test.a)

# class >> @property
print(test.method_with_property)
print(test.method_without_property())

# map() 会根据提供的函数对指定序列做映射
print(list(map(lambda x: x * x, list(range(10)))))