Python由于语言的简洁性,让我们以人类思考的方式来写代码,新手更容易上手,老鸟更爱不释手。
要写出 Pythonic(优雅的、地道的、整洁的)代码,还要平时多观察那些大牛代码,Github 上有很多非常优秀的源代码值得阅读,比如:requests、flask、tornado,这里小明收集了一些常见的 Pythonic 写法,帮助你养成写优秀代码的习惯。
01. 变量交换
Bad
tmp = a a = b b = tmp
Pythonic
a,b = b,a
02. 列表推导
Bad
my_list = [] for i in range(10): my_list.append(i*2)
Pythonic
my_list = [i*2 for i in range(10)]
03. 单行表达式
虽然列表推导式由于其简洁性及表达性,被广受推崇。
但是有许多可以写成单行的表达式,并不是好的做法。
Bad
print 'one'; print 'two' if x == 1: print 'one' if <complex comparison> and <other complex comparison>: # do something
Pythonic
print 'one' print 'two' if x == 1: print 'one' cond1 = <complex comparison> cond2 = <other complex comparison> if cond1 and cond2: # do something
04. 带索引遍历
Bad
for i in range(len(my_list)): print(i, "-->", my_list[i])
Pythonic
for i,item in enumerate(my_list): print(i, "-->",item)
05. 序列解包
Pythonic
a, *rest = [1, 2, 3] # a = 1, rest = [2, 3] a, *middle, c = [1, 2, 3, 4] # a = 1, middle = [2, 3], c = 4
06. 字符串拼接
Bad
letters = ['s', 'p', 'a', 'm'] s="" for let in letters: s += let
Pythonic
letters = ['s', 'p', 'a', 'm'] word = ''.join(letters)
07. 真假判断
Bad
if attr == True: print 'True!' if attr == None: print 'attr is None!'
Pythonic
if attr: print 'attr is truthy!' if not attr: print 'attr is falsey!' if attr is None: print 'attr is None!'
08. 访问字典元素
Bad
d = {'hello': 'world'} if d.has_key('hello'): print d['hello'] # prints 'world' else: print 'default_value'
Pythonic
d = {'hello': 'world'} print d.get('hello', 'default_value') # prints 'world' print d.get('thingy', 'default_value') # prints 'default_value' # Or: if 'hello' in d: print d['hello']
09. 操作列表
Bad
a = [3, 4, 5] b = [] for i in a: if i > 4: b.append(i)
Pythonic
a = [3, 4, 5] b = [i for i in a if i > 4] # Or: b = filter(lambda x: x > 4, a)
Bad
a = [3, 4, 5] for i in range(len(a)): a[i] += 3
Pythonic
a = [3, 4, 5] a = [i + 3 for i in a] # Or: a = map(lambda i: i + 3, a)
10. 文件读取
Bad
f = open('file.txt') a = f.read() print a f.close()
Pythonic
with open('file.txt') as f: for line in f: print line
11. 代码续行
Bad
my_very_big_string = """For a long time I used to go to bed early. Sometimes, when I had put out my candle, my eyes would close so quickly that I had not even time to say “I'm going to sleep.”""" from some.deep.module.inside.a.module import a_nice_function, another_nice_function, yet_another_nice_function
Pythonic
my_very_big_string = ( "For a long time I used to go to bed early. Sometimes, " "when I had put out my candle, my eyes would close so quickly " "that I had not even time to say “I'm going to sleep.”" ) from some.deep.module.inside.a.module import ( a_nice_function, another_nice_function, yet_another_nice_function)
12. 显式代码
Bad
def make_complex(*args): x, y = args return dict(**locals())
Pythonic
def make_complex(x, y): return {'x': x, 'y': y}
13. 使用占位符
Pythonic
filename = 'foobar.txt' basename, _, ext = filename.rpartition('.')
14. 链式比较
Bad
if age > 18 and age < 60: print("young man")
Pythonic
if 18 < age < 60: print("young man")
理解了链式比较操作,那么你应该知道为什么下面这行代码输出的结果是 False
> False == False == True False
15. 三目运算
这个保留意见。随使用习惯就好。
Bad
if a > 2: b = 2 else: b = 1 #b = 2
Pythonic
a = 3 b = 2 if a > 2 else 1 #b = 2
参考文档
http://docs.python-guide.org/en/latest/writing/style/
https://foofish.net/idiomatic_part2.html
Pythonic
稳了!魔兽国服回归的3条重磅消息!官宣时间再确认!
昨天有一位朋友在大神群里分享,自己亚服账号被封号之后居然弹出了国服的封号信息对话框。
这里面让他访问的是一个国服的战网网址,com.cn和后面的zh都非常明白地表明这就是国服战网。
而他在复制这个网址并且进行登录之后,确实是网易的网址,也就是我们熟悉的停服之后国服发布的暴雪游戏产品运营到期开放退款的说明。这是一件比较奇怪的事情,因为以前都没有出现这样的情况,现在突然提示跳转到国服战网的网址,是不是说明了简体中文客户端已经开始进行更新了呢?
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