我有一个很长的疑问。我想用Python将它分成几行。在JavaScript中实现这一点的一种方法是使用几个句子并用+运算符将它们连接起来(我知道,也许这不是最有效的方法,但我并不真正关心这个阶段的性能,只是代码的可读性)。例子:

var long_string = 'some text not important. just garbage to' +
                      'illustrate my example';

我尝试在Python中做类似的事情,但没有成功,所以我使用了\来拆分长字符串。然而,我不确定这是否是唯一/最好/最蟒蛇的做法。看起来很尴尬。实际代码:

query = 'SELECT action.descr as "action", '\
    'role.id as role_id,'\
    'role.descr as role'\
    'FROM '\
    'public.role_action_def,'\
    'public.role,'\
    'public.record_def, '\
    'public.action'\
    'WHERE role.id = role_action_def.role_id AND'\
    'record_def.id = role_action_def.def_id AND'\
    'action.id = role_action_def.action_id AND'\
    'role_action_def.account_id = ' + account_id + ' AND'\
    'record_def.account_id=' + account_id + ' AND'\
    'def_id=' + def_id

当前回答

嗯。

我知道这个问题发布已经很久了。但我刚刚找到了我想用来为项目中的变量分配长字符串和多行字符串的样式。这需要一点额外的运行时间,但仍然保留了代码的美感,即使我将字符串分配给的变量缩进很大。

    # Suppose the following code is heavily indented
    line3header = "Third"

    variable = fr"""

First line.
Second line.
{line3header} line.
{{}} line.
...
The last line.

    """.strip()
    """A variable whose name is Variable.

    You can even add a docstring here.
    """

    variable = variable.format("Fourth")
    print(variable)
    variable += "\n"
    print(variable, end="")

就这样。

其他回答

为了在字典内定义长字符串,保留换行符但省略空格,我最终以如下常量定义字符串:

LONG_STRING = \
"""
This is a long sting
that contains newlines.
The newlines are important.
"""

my_dict = {
   'foo': 'bar',
   'string': LONG_STRING
}

我发现自己对这个很满意:

string = """This is a
very long string,
containing commas,
that I split up
for readability""".replace('\n',' ')

例如:

sql = ("select field1, field2, field3, field4 "
       "from table "
       "where condition1={} "
       "and condition2={}").format(1, 2)

Output: 'select field1, field2, field3, field4 from table
         where condition1=1 and condition2=2'

如果条件的值应该是字符串,可以这样做:

sql = ("select field1, field2, field3, field4 "
       "from table "
       "where condition1='{0}' "
       "and condition2='{1}'").format('2016-10-12', '2017-10-12')

Output: "select field1, field2, field3, field4 from table where
         condition1='2016-10-12' and condition2='2017-10-12'"

tl;dr:使用“”和“”来换行字符串,如中所示

string = """\
This is a long string
spanning multiple lines.
"""

从Python官方文档中:

字符串文本可以跨越多行。一种方法是使用三引号:“”“…”“”或“”“”…“”。行的结束是自动的包含在字符串中,但可以通过添加\在线路的末端。以下示例:

print("""\
Usage: thingy [OPTIONS]
     -h                        Display this usage message
     -H hostname               Hostname to connect to
""")

生成以下输出(注意,初始换行符不是包括在内):

Usage: thingy [OPTIONS]
     -h                        Display this usage message
     -H hostname               Hostname to connect to

用\换行对我很有用。下面是一个例子:

longStr = "This is a very long string " \
        "that I wrote to help somebody " \
        "who had a question about " \
        "writing long strings in Python"