问题
I need to parse byte string which spans more than one line in the source code. Like this
self.file.write(b'#compdef %s\n\n'
'_arguments -s -A "-*" \\\n' % (self.cmdName,))
this line throws the following exception
builtins.SyntaxError: cannot mix bytes and nonbytes literals
which can be fixed in the following way
self.file.write(b'#compdef %s\n\n\'\'_arguments -s -A "-*" \\\n' % (self.cmdName,))
Notice the backslashes after \n. but this fix does the follow the project rules of less than 79 characters per line.
How do I fix this?
The code works fine on Python 2 but fails on Python 3.
回答1:
You are fine to use multiple string literals, but they need to be of the same type. You are missing the b prefix on the second line:
self.file.write(b'#compdef %s\n\n'
b'_arguments -s -A "-*" \\\n' % (self.cmdName,))
Only when using string literals of the same type will the python parser merge these into one longer bytes string object.
It worked on Python 2 because the b prefix is a no-op; b'..' and '..' produce the same type of object. The b prefix only exists in Python 2 to make it easier to write code for both Python 2 and 3 in the same codebase (polyglot).
来源：https://stackoverflow.com/questions/38326297/byte-string-spanning-more-than-one-line