##不推薦
if x == True:
  # ....
if len(items) != 0:
  # ...
if items != []:
  # ... 

##推薦
if x:
  # ....
if items:
  # ...

##不推薦
items = 'zero one two three'.split()
# method 1
i = 0
for item in items:
  print i, item
  i += 1
# method 2
for i in range(len(items)):
  print i, items[i]

##推薦
items = 'zero one two three'.split()
for i, item in enumerate(items):
  print i, item

##不推薦
new_list = []
for item in a_list:
  if condition(item):
    new_list.append(fn(item)) 

##推薦
new_list = [fn(item) for item in a_list if condition(item)]

##不推薦
for sub_list in nested_list:
  if list_condition(sub_list):
    for item in sub_list:
      if item_condition(item):
        # do something... 
##推薦
gen = (item for sl in nested_list if list_condition(sl) \
      for item in sl if item_condition(item))
for item in gen:
  # do something...

##不推薦
for x in x_list:
  for y in y_list:
    for z in z_list:
      # do something for x & y 

##推薦
from itertools import product
for x, y, z in product(x_list, y_list, z_list):
  # do something for x, y, z

##不推薦
def my_range(n):
  i = 0
  result = []
  while i < n:
    result.append(fn(i))
    i += 1
  return result # 返回列表

##推薦
def my_range(n):
  i = 0
  result = []
  while i < n:
    yield fn(i) # 使用生成器代替列表
    i += 1
# 盡量用生成器代替列表，除非必須用到列表特有的函數(shù)。

##不推薦
reduce(rf, filter(ff, map(mf, a_list)))

##推薦
from itertools import ifilter, imap
reduce(rf, ifilter(ff, imap(mf, a_list)))
# lazy evaluation 會(huì)帶來(lái)更高的內(nèi)存使用效率，特別是當(dāng)處理大數(shù)據(jù)操作的時(shí)候。

##不推薦
found = False
for item in a_list:
  if condition(item):
    found = True
    break
if found:
  # do something if found... 

##推薦
if any(condition(item) for item in a_list):
  # do something if found...

##不推薦
class Clock(object):
  def __init__(self):
    self.__hour = 1
  def setHour(self, hour):
    if 25 > hour > 0: self.__hour = hour
    else: raise BadHourException
  def getHour(self):
    return self.__hour

##推薦
class Clock(object):
  def __init__(self):
    self.__hour = 1
  def __setHour(self, hour):
    if 25 > hour > 0: self.__hour = hour
    else: raise BadHourException
  def __getHour(self):
    return self.__hour
  hour = property(__getHour, __setHour)

##不推薦
f = open("some_file.txt")
try:
  data = f.read()
  # 其他文件操作..
finally:
  f.close()

##推薦
with open("some_file.txt") as f:
  data = f.read()
  # 其他文件操作...

##不推薦
try:
  os.remove("somefile.txt")
except OSError:
  pass

##推薦
from contextlib import ignored # Python 3 only

with ignored(OSError):
  os.remove("somefile.txt")

##不推薦
import threading
lock = threading.Lock()

lock.acquire()
try:
  # 互斥操作...
finally:
  lock.release()

##推薦
import threading
lock = threading.Lock()

with lock:
  # 互斥操作...