Python 3.5 typed NamedTuple syntax produces Syntax

问题:

I get a SyntaxError: invalid syntax error when I try the new typed namedtuple syntax:

class Employee(NamedTuple):
    name: str
    id: int

in Python 3.5.2 even though according to the documentation it should be valid from 3.5+ onwards. Am I missing something? I've imported NamedTuple from typing in the code.

回答1:

The syntax to declare the types for the name and id fields you are using requires Python 3.6 or up. Python 3.5 does not support the variable-level type hints required.

From the typing.NamedTuple documentation:

Changed in version 3.6: Added support for PEP 526 variable annotation syntax.

Use the backwards compatible syntax also included in the documentation:

Employee = NamedTuple('Employee', [('name', str), ('id', int)])

so listing the field names as (name, type) tuples.

If you are using Python 3.5, you may want to switch to the Python 3.5 version of the documentation instead (there is a selector in the top-left corner, or you can just replace the 3 in the URL with 3.5).