正如PEP8所建议的那样，在python程序中保持低于80列的规则，对于长字符串，我怎么能遵守这个规则呢?
s = "this is my really, really, really, really, really, really, really long string that I'd like to shorten."
我该如何把它扩展到下面一行呢?
s = "this is my really, really, really, really, really, really" +
"really long string that I'd like to shorten."
当前回答
可用的选项:
反斜杠:"foo" \ "bar" "foo" + " \ "bar" 括号: (“foo”“酒吧”) 带加号的括号:("foo" + "bar") PEP8, E502:括号之间的反斜杠是多余的
避免
避免使用逗号:("foo"， "bar")来定义一个元组。
>>> s = "a" \
... "b"
>>> s
'ab'
>>> type(s)
<class 'str'>
>>> s = "a" + \
... "b"
>>> s
'ab'
>>> type(s)
<class 'str'>
>>> s = ("a"
... "b")
>>> type(s)
<class 'str'>
>>> print(s)
ab
>>> s = ("a",
... "b")
>>> type(s)
<class 'tuple'>
>>> s = ("a" +
... "b")
>>> type(s)
<class 'str'>
>>> print(s)
ab
>>>
其他回答
您丢失了一个空格，您可能需要一个行延续字符，即。一个\。
s = "this is my really, really, really, really, really, really" + \
" really long string that I'd like to shorten."
甚至:
s = "this is my really, really, really, really, really, really" \
" really long string that I'd like to shorten."
parns也可以代替行续符，但可能会有人认为您打算使用元组，而只是忘记了逗号。举个例子:
s = ("this is my really, really, really, really, really, really"
" really long string that I'd like to shorten.")
对比:
s = ("this is my really, really, really, really, really, really",
" really long string that I'd like to shorten.")
使用Python的动态类型，代码可以以任何一种方式运行，但会产生不正确的结果。
因为相邻的字符串常量是自动连接的，你可以这样编码:
s = ("this is my really, really, really, really, really, really, "
"really long string that I'd like to shorten.")
注意没有加号，我在示例的格式后面添加了额外的逗号和空格。
就我个人而言，我不喜欢反斜杠，我记得在某个地方读到过，它的使用实际上是被反对的，而支持这种更明确的形式。记住“显式优于隐式”。
我认为反斜杠不太清楚，也不太有用，因为这实际上是转义换行符。如果需要的话，不能在它后面加上行结束注释。可以通过串接字符串常量来实现:
s = ("this is my really, really, really, really, really, really, " # comments ok
"really long string that I'd like to shorten.")
我使用谷歌搜索“python行长”，它返回PEP8链接作为第一个结果，但也链接到另一个关于这个主题的StackOverflow帖子:“为什么python PEP-8应该指定79个字符的最大行长?”
另一个好的搜索短语是“python line continuation”。
可用的选项:
反斜杠:"foo" \ "bar" "foo" + " \ "bar" 括号: (“foo”“酒吧”) 带加号的括号:("foo" + "bar") PEP8, E502:括号之间的反斜杠是多余的
避免
避免使用逗号:("foo"， "bar")来定义一个元组。
>>> s = "a" \
... "b"
>>> s
'ab'
>>> type(s)
<class 'str'>
>>> s = "a" + \
... "b"
>>> s
'ab'
>>> type(s)
<class 'str'>
>>> s = ("a"
... "b")
>>> type(s)
<class 'str'>
>>> print(s)
ab
>>> s = ("a",
... "b")
>>> type(s)
<class 'tuple'>
>>> s = ("a" +
... "b")
>>> type(s)
<class 'str'>
>>> print(s)
ab
>>>
隐式连接可能是最干净的解决方案:
s = "this is my really, really, really, really, really, really," \
" really long string that I'd like to shorten."
编辑经过反思，我同意托德的建议，使用括号而不是行接续更好，因为他给出了所有的理由。我唯一的犹豫是，用括号括起来的字符串和元组比较容易混淆。
如果你必须插入一个长字符串文字，并希望flake8关闭，你可以使用它的关闭指令。例如，在一个测试例程中，我定义了一些假的CSV输入。我发现把它分成更多行会非常混乱，所以我决定添加一个# noqa: E501，如下所示:
csv_test_content = """"STATION","DATE","SOURCE","LATITUDE","LONGITUDE","ELEVATION","NAME","REPORT_TYPE","CALL_SIGN","QUALITY_CONTROL","WND","CIG","VIS","TMP","DEW","SLP","AA1","AA2","AY1","AY2","GF1","MW1","REM"
"94733099999","2019-01-03T22:00:00","4","-32.5833333","151.1666666","45.0","SINGLETON STP, AS","FM-12","99999","V020","050,1,N,0010,1","22000,1,9,N","025000,1,9,9","+0260,1","+0210,1","99999,9","24,0000,9,1",,"0,1,02,1","0,1,02,1","01,99,1,99,9,99,9,99999,9,99,9,99,9","01,1","SYN05294733 11/75 10502 10260 20210 60004 70100 333 70000="
"94733099999","2019-01-04T04:00:00","4","-32.5833333","151.1666666","45.0","SINGLETON STP, AS","FM-12","99999","V020","090,1,N,0021,1","22000,1,9,N","025000,1,9,9","+0378,1","+0172,1","99999,9","06,0000,9,1",,"0,1,02,1","0,1,02,1","03,99,1,99,9,99,9,99999,9,99,9,99,9","03,1","SYN04294733 11/75 30904 10378 20172 60001 70300="
"94733099999","2019-01-04T22:00:00","4","-32.5833333","151.1666666","45.0","SINGLETON STP, AS","FM-12","99999","V020","290,1,N,0057,1","99999,9,9,N","020000,1,9,9","+0339,1","+0201,1","99999,9","24,0000,9,1",,"0,1,02,1","0,1,02,1",,"02,1","SYN05294733 11970 02911 10339 20201 60004 70200 333 70000="
"94733099999","2019-01-05T22:00:00","4","-32.5833333","151.1666666","45.0","SINGLETON STP, AS","FM-12","99999","V020","200,1,N,0026,1","99999,9,9,N","000100,1,9,9","+0209,1","+0193,1","99999,9","24,0004,3,1",,"1,1,02,1","1,1,02,1","08,99,1,99,9,99,9,99999,9,99,9,99,9","51,1","SYN05294733 11/01 82005 10209 20193 69944 75111 333 70004="
"94733099999","2019-01-08T04:00:00","4","-32.5833333","151.1666666","45.0","SINGLETON STP, AS","FM-12","99999","V020","070,1,N,0026,1","22000,1,9,N","025000,1,9,9","+0344,1","+0213,1","99999,9","06,0000,9,1",,"2,1,02,1","2,1,02,1","04,99,1,99,9,99,9,99999,9,99,9,99,9","02,1","SYN04294733 11/75 40705 10344 20213 60001 70222="
""" # noqa: E501
