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| -rw-r--r-- | Doc/library/typing.rst | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst index 11c39a4..60bf06e 100644 --- a/Doc/library/typing.rst +++ b/Doc/library/typing.rst @@ -849,6 +849,21 @@ using ``[]``. concat(b"foo", b"bar") # OK, output has type 'bytes' concat("foo", b"bar") # Error, cannot mix str and bytes + Note that, despite its name, ``AnyStr`` has nothing to do with the + :class:`Any` type, nor does it mean "any string". In particular, ``AnyStr`` + and ``str | bytes`` are different from each other and have different use + cases:: + + # Invalid use of AnyStr: + # The type variable is used only once in the function signature, + # so cannot be "solved" by the type checker + def greet_bad(cond: bool) -> AnyStr: + return "hi there!" if cond else b"greetings!" + + # The better way of annotating this function: + def greet_proper(cond: bool) -> str | bytes: + return "hi there!" if cond else b"greetings!" + .. data:: LiteralString Special type that includes only literal strings. |