不能断言对象的类型? [英] Can not assert type of an object?

问题描述

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.

... python3...

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

..?我希望类初始值设定项成为对象创建的严格过滤器.

..? I want the class initializer be a harsh filter for object creation.

你是怎么处理的?对我来说这一切似乎都很好.

How do you deal with that? It all seems to be OK to me.

推荐答案

与其与 type 进行比较(您当然不应该将其作为字符串！)，请使用 isinstance.另外，您不应该像那样使用 assert，请尝试以下操作:

Rather than comparing to type (which you certainly shouldn't do as a string!), use isinstance. Also, you shouldn't use assert like that, try something like:

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

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