不能断言对象的类型？

Question

为什么这个来源...

"""
[...]
"""
#   Import the standard date and time system.
from datetime import datetime as dt
#   Ommited the remaining imports section
class CuteClass(object):
    """
    [...]
    """
    def __init__(self, parameter_zero, date, parameter_two):
        """
        [...]
        """
        #   Omitted parameter_zero processing.
        print(type(date)) # FIXME delete this sentence.
        if sys.version_info[0] == 2:
            assert (type(date) == "<type 'datetime.datetime'>",
                    'assertion failed creating a CuteClass object')
        elif sys.version_info[0] == 3:
            assert (type(date) == "<class 'datetime.datetime'>",
                    'assertion failed creating a CuteClass object')
        else:
            sys.exit(inspect.getframeinfo(inspect.currentframe()))
        self.date = date
        #   Omitted remaining parameters' processing.

...产生python3...

<class 'datetime.datetime'>
Traceback (most recent call last):
[...]
  File "...", line 37, in __init__
    assert type(date) == "<class 'datetime.datetime'>"
AssertionError
$ _

..？我希望类初始化器成为对象创建的苛刻过滤器。

你是怎么处理的？对我来说一切都很好。

Answer 1

我问了鸭子，然后我告诉鸭子我应该这样做

        assert (str(type(date)) == "<class 'datetime.datetime'>",
                'assertion failed creating a CuteClass object')

而不是

        assert (type(date) == "<class 'datetime.datetime'>",
                'assertion failed creating a CuteClass object')

Answer 2

与其比较type（你当然不应该将其作为字符串！），不如使用isinstance。另外，你不应该像这样使用assert，试试这样的：

if not isinstance(date, dt): # note you have aliased datetime.datetime
    raise TypeError(...)