python - f 字符串不支持行连接吗？

Question

Python 3.6 中的 f-strings 不支持以下语法吗？如果我行加入我的 f 字符串，则不会发生替换:

SUB_MSG = "This is the original message."

MAIN_MSG = f"This longer message is intended to contain " \
             "the sub-message here: {SUB_MSG}"

print(MAIN_MSG)

返回:

This longer message is intended to contain the sub-message here: {SUB_MSG}

如果我删除行连接:

SUB_MSG = "This is the original message."

MAIN_MSG = f"This longer message is intended to contain the sub-message here: {SUB_MSG}"

print(MAIN_MSG)

它按预期工作:

This longer message is intended to contain the sub-message here: This is the original message.

在PEP 498 ，反斜杠 在 一个 f 字符串中明确不支持:

Escape sequences

Backslashes may not appear inside the expression portions of f-strings, so you cannot use them, for example, to escape quotes inside f-strings:

>>> f'{\'quoted string\'}'

行连接是否被视为“在 f 字符串的表达式部分内”，因此不受支持？

Answer 1

您必须将两个字符串都标记为 f-strings 才能使其正常工作，否则第二个字符串将被解释为普通字符串:

SUB_MSG = "This is the original message."

MAIN_MSG = f"test " \
           f"{SUB_MSG}"

print(MAIN_MSG)

好吧，在这种情况下，您也可以将第二个字符串设为 f 字符串，因为第一个字符串不包含任何要插入的内容:

MAIN_MSG = "test " \
           f"{SUB_MSG}"

请注意，这会影响所有字符串前缀，而不仅仅是 f 字符串:

a = r"\n" \
     "\n"
a   # '\\n\n'   <- only the first one was interpreted as raw string

a = b"\n" \
     "\n"   
# SyntaxError: cannot mix bytes and nonbytes literals