样式，格式化切片运算符 [英] style, formatting the slice operator

问题描述

PEP 8 没有提及切片运算符。从我的理解，不像其他运算符，它不应该被空格包围

  spam [3：5]＃OK 
 spam [3：5]＃NOT OK 
  

使用复杂表达式时，一个被认为是更好的风格

 
 1.垃圾邮件[ham（66）// 3：44 + eggs 2. spam [ham（66）// 3：44 + eggs（）] 
 3. spam [ham（66）// 3：44 + eggs（）] 
 4.别的什么？正如你已经提到的，PEP8没有明确提到该格式的slice运算符，因此，但是 spam [3：5] 肯定更常见，IMHO更易读。
 
 
 
如果 pep8 checker 是什么，：之前的空格将被标记 p> 
 
 
  [me @ home] $ pep8<（echospam [3:44]）＃无警告
 [ me @ home] $ pep8<（echospam [3：44]）
 / dev / fd / 63：1：7：E203之前的空白'：'
  
 ...但这只是因为它假定：并且在操作员之前没有空间。  spam [3：44] 因为这个原因，但似乎不对。
 
 
 
计数，我坚持 spam [3:44] 。 
 
 
 
 
 
 
嵌套算术运算有点棘手。在您的3个示例中，只有第2个通过PEP8验证：
  [me @ home] $ pep8< [ham（66）// 3：44 + eggs（）]）
 / dev / fd / 63：1：13：E225缺少操作符周围的空格
 
 [ $ pep8<（echospam [ham（66）// 3:44 + eggs（）]）＃OK 
 
 [me @ home] $ pep8< （66）// 3：44 + eggs（）]）
 / dev / fd / 63：1：18：E203之前的空白'：'
  
但是，我发现上面所有的一切都很难一目了然。
 
 
 
符合PEP8，我亲自去：
  spam [（ham（66）/ / 3）:( 44 + eggs（））] 
  
 > 
 
 
  s_from = ham（66）// 3 
 s_to = 44 + eggs $ b spam [s_from：s_to] 
  
 
PEP 8 doesn't mention the slice operator. From my understanding, unlike other operators, it should not be surrounded with whitespace
spam[3:5]   # OK
spam[3 : 5] # NOT OK
Does this hold when using complex expressions, that is, which one is considered better style
     1. spam[ham(66)//3:44+eggs()]
     2. spam[ham(66) // 3: 44 + eggs()]
     3. spam[ham(66) // 3 : 44 + eggs()]
     4. something else?

解决方案
As you already mentioned, PEP8 doesn't explicitly mention the slice operator in that format, but spam[3:5] is definitely more common and IMHO more readable.

If pep8 checker is anything to go by, the space before : will be flagged up
[me@home]$ pep8  <(echo "spam[3:44]")   # no warnings
[me@home]$ pep8  <(echo "spam[3 : 44]")  
/dev/fd/63:1:7: E203 whitespace before ':'
... but that's only because of it assumes : to be the operator for defining a literal dict and no space is expected before the operator. spam[3: 44] passes for that reason, but  that just doesn't seem right.

On that count, I'd stick to spam[3:44]. 



Nested arithmetic operations are a little trickier. Of your 3 examples, only the 2nd one passes PEP8 validation:
[me@home]$ pep8 <(echo "spam[ham(66)//3:44+eggs()]")
/dev/fd/63:1:13: E225 missing whitespace around operator

[me@home]$ pep8 <(echo "spam[ham(66) // 3:44 + eggs()]")  # OK

[me@home]$ pep8 <(echo "spam[ham(66) // 3 : 44 + eggs()]")
/dev/fd/63:1:18: E203 whitespace before ':'
However, I find all of the above difficult to parse by eye at first glance.

For readability and compliance with PEP8, I'd personally go for:
 spam[(ham(66) // 3):(44 + eggs())]
Or for more complication operations:
 s_from = ham(66) // 3 
 s_to = 44 + eggs()
 spam[s_from:s_to]


                        
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