一行末尾的反斜杠有什么用？

Question

Just found the following module import in a Python code:

from sqlalchemy.ext.declarative import declarative_base,\
      AbstractConcreteBase

I am curious about the backslash \ at the end of the first line. What's the purpose of it? Wouldn't it be the same as the following?

from sqlalchemy.ext.declarative import declarative_base, AbstractConcreteBase

Answer 1

Yep, it's exactly the same and this is the point of the backslash — it escapes the newline, allowing this long line to be split in two. An alternative is to use parentheses:

from sqlalchemy.ext.declarative import (declarative_base,
      AbstractConcreteBase)

While this is a syntax error:

from sqlalchemy.ext.declarative import declarative_base,
      AbstractConcreteBase

Answer 2

In the context of line-oriented text, especially source code for some programming languages, it is often used at the end of a line to indicate that the trailing newline character should be ignored, so that the following line is treated as if it were part of the current line.